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Rotor Rooter
02-21-2009, 12:43 PM
JensSimilar performance as the Schoefmann machine, should be the common goal for this category of rotor craft – I think.
That might be the overall parameters in which a number of people could have a collective technical participation, while at the same time having independence over the specifics of their own project.

This would be a relatively low cost entry into helicopters.

Over the years some have commented on the need for some type of simple landing gear. Providing for this small weight increase may not be detrimental to the above common goal, since the builders probably have a greater spread in their weight differences.

If the goal is to make a super ‘back pack heli’, it is for the more than super professional or some constructors outside this planet ;-)
If the goal is a homebuilt ‘back pack heli’, the required performances for the machine should be much lower.
Agreed, but as with the gyrocopter, some would eventually want to purchase their blades or hub parts, etc, and this presents an potential oportunity for one or more to satisfy this requirement.

In addition, newer ideas may not result in weight increases, nor do the have to necessarity result in cost increases. For example, initially symetrical NACA 0012 blades might be made by the the builders, then someone produces LH and RH asymetrical VR-7 blades. A number of years ago a company called Carson Helicopters started producing blades for the old Sikorsky S-61 (http://www.continuum-dynamics.com/documents/RAN005.pdf), which increased the lift by 1,800 pounds.


Last but not least, a project of this type might bring other like minded participants onto this forum. Helicopter oriented people who currently stay away.


Dave

Arnie Madsen
02-21-2009, 04:53 PM
Take a look at the Mosquito Air and tell me what you think.

If you put your seatbelt and shoulder harness on tight you have a backpack helicopter . Right ?? A lightweight 3 point landing gear is included. It has a simple drive train , a proven main rotor and tail rotor system. See attached picture below.

The hard part , or the obstacle for most people on this type of machine is the cost of training. For this reason we all want to out smart the system and build something in our garage . Something we can strap on our backs and just hover a bit around the neighborhood.

Because we cannot carry a long tailboom protruding out the back , we decide to build a co-axial overhead rotor system. It is compact and the rotor is a small diameter. Should be easy to handle is what we tell ourselves. Some truth to that. An overhead coaxial rotor can eliminate a lot of torque and coupling and control issues.

But lets face it , is still a helicopter. To fly this machine you need to be a helicopter pilot. We are right back where we started. The largest heavy lift co-axial helicopter built in the USSR or a small one built in our garage and strapped to our back are the same. They both will fly pretty much the same. Only the size and landing gear are different.

There is nothing I would like better than to be able to strap on a backpack helicopter and go flying. That would be the ultimate. Hang in the air and show off to all the friends. But would I ? Well lets see........

Assuming I can already fly a helicopter and my legs are in good shape to do a run-on landing if required there is still a problem. What happens if I need to land and the machine has decided to have me flying sideways (remember we have no rudder or tail rotor).
I can run pretty fast forward , but not sideways or backwards or whatever. I could be in trouble and with one stumble I and the machine become a mixture of arms and legs and rotorblades.

To solve these safety concerns we could add a roll bar , some landing gear , a rudder or tail rotor for directional control and all of a sudden you have something similar to the picture below. Right back to where we started. But you still need to be a helicopter pilot ..... there is that problem again .... darn ... !!!!

$3000 to $5000 can buy 10 to 15 hours of dual instruction at a certified flight school in a certified helicopter. Tell the flight school you only want 10-15 hours as a good introduction to this type of flying. It will be the most fun you ever had for a small amount of money. By 8-10 hours you will be flying the machine yourself with the instructor to rescue you once in a while.

At 10-15 hours of pure fun and frustration you will also have a great respect for rotors turning overhead. So much that you would think twice about strapping something on your back to cruise the neighborhood. The pure exhilaration of 15 hours of helicopter instruction will keep you happy for a long time. It will sharpen your mind , your reflexes , and your situational awareness of everything around you. Even when you are driving home from the airport. You will respect this type of flying and wish to do it safely , which is most important.

I love this thread and have followed all the posts. I like the ideas, the home built components , the clever thinking. Just remember it is a helicopter you are building. To fly one , you need to be a helicopter pilot. Here is hoping you all can find $3000 to $5000 to do the real thing for a few hours. Best wishes to all.



Arnie
Bell 47 G2

Monk
02-21-2009, 06:24 PM
your airfoil looks good, why not make them from foam with a metal spar and then glass them over? you very well might can get away with glassing over what you have there.

anyway just an idea.

That's a good advice Animal, but I was thinking why not use professionally made propellers from known manufacturer's. Money? That can be recouped by selling the propellers after you've proven your design.


There are many homebuiders out there working on FWs that'll buy second hand propellers.

Rotor Rooter
02-21-2009, 07:09 PM
Hundreds, or perhaps thousands, have tried to discover that elusive rotorcraft. A rotorcraft that can be bought economically, built reliably, and flown safely. So far, no one has found a way to satisfy Igor's 'helicopter in every garage'.

Perhaps John Uptigrove has come the closest; and this may be due to his emphasis on engineering over marketing. It appears that he had a fixation on the number '254'. The empty weight of his craft was going to come in at under 254 pounds, come hell or high water. If an improvement involved two pounds of additional weight then he was confronted with the more difficult task of finding those places where he could safely trim two pounds from the craft. The end result seem to be a helicopter where no component, including the engine, is over-loaded due to 'weight creep".


This story has to be going some where........
Oh! Yes. Arnie's good arguments.

Perhaps, the only problem with John's craft is the difficulty of piloting it, particularly for recreational fliers. Perhaps, a laterally symmetrical craft build to John's standards might eventually put that extra space in the nation's garages to good use.

Most ideas look good in the beginning. Then the problems start showing up as one drills down deeper into them. The coaxial configuration is at least starting off on the right foot. Ultralight coaxials might be fun to discuss and build no matter how successful the eventual outcome is. God knows enough time and effort has been devoted to the single+tail rotor configuration.

In addition, I've got a couple of really, really, really good ideas for a simple coaxial; http://www.unicopter.com/Chairshot.gif
well :o ; good so far and the drill is still moving deeper.

Someone with a deep understanding of rotorcraft please break the drill or start the patent application.

Dave

Monk
02-21-2009, 07:17 PM
Perhaps John Uptigrove has come the closest; and this may be due to his emphasis on engineering over marketing. It appears that he had a fixation on the number '254'. The empty weight of his craft was going to come in at under 254 pounds, come hell or high water. If an improvement involved two pounds of additional weight then he was confronted with the more difficult task of finding those places where he could safely trim two pounds from the craft. The end result seem to be a helicopter where no component, including the engine, is over-loaded due to 'weight creep".


Dave

I was thinking that as well Dave. Doug S's AW-95 was under 254#s too and I almost bought it when it was for sale (his prototype).

I'm still kicking myself in the arse for not buying from John U when he was selling them for $10,000. It was too early in the design and I wanted to see a few more flying first.

Jens
02-22-2009, 01:17 AM
Hi Arnie,

Yes, the Mosquito is a good example of how small a helicopter can get.
And yes “If you put your seatbelt and shoulder harness on tight you have a backpack helicopter “ – that works.
So we have nailed down pretty narrow what it takes to make the smallest possible helicopter.

But is a rotor craft machine with similar performance as the Schoefmann machine a helicopter?
I think a better word would be hovercopter.

Schoefmann or similar differs from the Mosquito or similar:

1. It don’t fly high.
2. It don’t fly fast.
3. It can be unloaded for all your body weight by means of using our legs.
4. It is dangerous, but not as dangerous as a Mosquito or similar.
__________________________________________________ _______________

I agree, any prior rotor craft training is recommended.
As you state Arnie “… great respect for rotors turning overhead”, will help keeping you body alive and in one part longer.

.

Jens
02-22-2009, 11:58 AM
The problem with the term ‘back pack helicopter’ is, that it has been used for a long time meaning a helicopter, just smaller, lighter, more handy and often also meaning home build and cheaper than the smallest 1 man ultra light helicopter.
A ‘back pack helicopter’ is a fantasy term = endless talk = no bodies in the air! Not so funny.

Lets us be more practical. A Back pack helicopter for real is a

Hovercopter: A rotorplane with landing gear combined with Foot launching that only can hover and fly low and slow.
Often homebuilt, cheaper, smaller, lighter and handier than an ultra light helicopter.

brett s
02-22-2009, 12:09 PM
It is dangerous, but not as dangerous as a Mosquito or similar.

That's where you're just plain wrong.

They'll all easily kill you if you do something stupid or something breaks, one without landing gear has the added bonus of potentially doing so if you just trip or slip a bit.

Jens
02-22-2009, 12:22 PM
Ohh... I did not mean without landing gear. Landing gear is absolutely nescessary.
One should be able to unload the body weight as Shoefmann does.
I used the term 'foot launched' because this is already in use with powered hang gliders and para gliders.
I may reword the definition - tomorrow.

I have just edited the definition in post #257

brett s
02-22-2009, 02:16 PM
It's still not going to be any safer just because it's smaller or foot launchable - how can it?

Any "helicopter" with enough power to hover (or even get close) has more than enough power to climb well out of ground effect. Fixed pitch, collective pitch - doesn't matter. You can't stop that short of tethering it to the ground.

If you try to go fixed pitch to keep things simpler, you've got rather unresponsive altitude control - both sluggish to respond & with limited authority. There's a limit to how fast or slow you can spin them on a given design...then there's the whole autorotation issue.

If you're hovering at 5-10' or so in a fixed pitch ship, you're probably going to break it if the engine quits - just like a "real" helicopter would do the same if the pilot didn't use collective to cushion the landing.

Monk
02-22-2009, 11:18 PM
http://www.sunflightcraft.com/en/coaxp.php

http://www.sunflightcraft.com/images/coax-p/CoaxP.jpg

Swap the prop and there you have it, instant backpack helicopter.



http://www.sunflightcraft.com/images/coax-p/Ramphos_CoaxP.jpghttp://www.sunflightcraft.com/images/coax-p/coaxp2.jpg

Jens
02-23-2009, 08:30 AM
Monk,
Might be a great idea. Around 400 lb thrust/lift is needed.
Maybe props and gear ratio should be bigger, but it comes close with their para trike pack - I think.

Yes, we are already getting some place here.
_________________________________________________


QUOTE brett, "It's still not going to be any safer just because it's smaller or foot launchable - how can it?"

“Landing gear combined with Foot launching” is essential here, because, as we agree, with fixed pitch rotors/props we have rather or too unresponsive altitude control – we can compensate for that by unloading the machine with our foots and legs, and thus get this sufficiently under control.

Thanks to Franz Schoefmann, we don’t have to guess too much about this.
We actually just have to look to know, that something can be done, and what range the safety is in:

http://www.flycastelluccio.at/cms/upload/gallerie/video/hubschraubermann.28.04.05_512.wmv

http://www.dailymotion.com/video/x3pj1w_helicoptere-personnel_extreme

Jens
03-01-2009, 03:52 AM
... I have been playing with the CNC to see how I could cut the rotor blade.


Hello Nick,
How are you getting along with your build?
You seam to have a very good time with it :)

http://www.rotaryforum.com/forum/attachment.php?attachmentid=52706&stc=1&thumb=1&d=1233593662

Maybe with short and stiff rotor blades, you don't need to worry about where COG is in the blades?
I saw once a picture of (very) home made blades that had big holes in them.
I guess they have never been used on an any rotor craft something...

But maybe one could use smaller holes and fill them with foam to move COG and take of a little weight - if any of this is needed.

Monte55
03-01-2009, 07:07 AM
Those rotors look nice. The other day I was thinking of lightening holes rather than a leading edge weight. Filling the holes with foam and then glassing seems like a plan. Do you think I need a spar for a solid wood rotor? I haven't done any more on the rotors. I've been figuring out how to adapt my centrifugal clutch to the motor output. I'll tell ya........milling hardened steel
gears etc is a real pain. Every adaption I do calls for me to buy a few new solid carbide end mills. On the clutch hub (hardened) I had to mill six slots
.224" deep and about that long. After three slots, the end mill was completely trashed. The second end mill finished the job but without sharpening it's not usable. I was cutting only .010" per pass but it sounded like it was grinding. No nice chips...more like dust. The third end mill is safe for now. I need to come up with a drive shaft from the clutch to the primary drive sprocket. I going to see about using a cv joint/shaft off an ATV. I'll need to modify it and make a slip joint of some fashion. Any idea on that???????? I need to get all these parts on the heli so I can come up with a total weight as to get a better idea of rotor size etc. If anyone has any interest in my build on this, I have a album with about 75 pics on another
forum. http://uk.groups.yahoo.com/group/Back-Pack-Helicopter/

In order to view the albums you will need to sign up as a member, it's free.

Nick

Jens
03-01-2009, 08:12 AM
...filling the holes with foam and then glassing seems like a plan.
... adapt my centrifugal clutch to the motor output.

With small holes maybe you don't need the glassing?

Centrifugal clutch is not from the 440 Kawasaki engine?

You use a flexible clutch on crankshaft - that means you intend to have ALL reduction of rpm in top?
About 7000 rpm on shaft from engine to top!? Do you know of some similar application?
I think you need a reduction here 1:2.5 or something and the rest in top.
In this case the centrifugal clutch should be with an adaptor directly on crankshaft. See picture of Mousquito drive.

Sita
03-01-2009, 09:36 AM
[QUOTE=brett s;276239].................................................. ...............................
If you try to go fixed pitch to keep things simpler, you've got rather unresponsive altitude control - both sluggish to respond & with limited authority. There's a limit to how fast or slow you can spin them on a given design...........................

QUOTE]

I've seen the Shöffman fly live and the repsonse to throtlle was completely under control.
He's been flying that contraption for several years now and if the throttle control was that bad he surely would have had an accident by now.
He can land very soft landings.
Comparing the BPH or Schöffman "heli" to even a very light helicopter like the Mosquito is like oranges and apples,they both are fruit but ......

Cita.

Monte55
03-03-2009, 06:32 AM
Even with small holes to lighten, why shouldn't they be covered?
The clutch is from a Yamaha 4 wheeler.
What do you mean by flexible clutch?
The 440 kaw engine max is 6000 rpm for stock. I don't plan to run it at max anyway. With my reduction, I figure the rotor will turn about 1000 rpm or close. I have to do it one way and if it doesn't work try something else. I believe this is the "Wright" way to to do it.....Nick






With small holes maybe you don't need the glassing?

Centrifugal clutch is not from the 440 Kawasaki engine?

You use a flexible clutch on crankshaft - that means you intend to have ALL reduction of rpm in top?
About 7000 rpm on shaft from engine to top!? Do you know of some similar application?
I think you need a reduction here 1:2.5 or something and the rest in top.
In this case the centrifugal clutch should be with an adaptor directly on crankshaft. See picture of Mousquito drive.

Jens
03-04-2009, 11:26 AM
1... small holes why shouldn't they be covered?
2. What do you mean by flexible clutch?
3.The 440 kaw engine max is 6000 rpm for stock. I don't plan to run it at max ..

1. the foam 'covers' the holes I think. Maybe give a little varnish on top.
2. See picture.
3. Okay, but also 5000 rpm is quite high - I think.

Wonder what the usualy rpm is on the drive shaft for tail rotors on helicopters.

Rotor Rooter
03-11-2009, 10:27 PM
This is not a back-pack helicopter but it is light and may suggest an idea or two, particularly since the rotor is teetering.


FLIGHT TESTS OF A MAN STANDING ON A PLATFORM SUPPORTED BY A TEETERING ROTOR (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930088114_1993088114.pdf)


Dave

Jens
03-12-2009, 01:53 PM
This is not a back-pack helicopter.....
FLIGHT TESTS OF A MAN STANDING ON A PLATFORM.....[/URL]

Great article.
Amazing how stable and controlable such a platform is.

I don't understand that actually. I think it should be quite unstable, but it is not.
He is standing on it and controling it without even touching the bars!?

A counter rotating gear box from Sun Flight Aircraft, a Rotax 503 and 2 props/rotor blades 10 ft. and we are hovering, flying 10-15 mph at 3-6 ft. :first:

Rotor craft can't get simpler than this:

Sita
03-23-2009, 07:44 AM
These pictures where sent to me by a French rotorcraft enthousiast

Rotor Rooter
03-23-2009, 01:33 PM
Cita, thanks for posting the pictures.

It is an interesting craft, with some neat ideas and others which are questionable.

Sita
03-23-2009, 01:56 PM
Hello Dave,


yes,wonder why they choose to place the rotors at head heigth.
It's a well made machine though.

Cita

Rotor Rooter
03-23-2009, 04:09 PM
yes,wonder why they choose to place the rotors at head heigth. Free shave and a haircut. :)

Jeanlulu
05-10-2009, 09:21 AM
For information, page 13

http://issuu.com/jeanlulu/docs/name9aec74

frenchy
05-26-2009, 09:54 AM
For information, page 13

http://issuu.com/jeanlulu/docs/name9aec74

hello jeanlulu
j'ais vu les images que tu as posté. et je voulais savoir qui l'a fabriqué
et si il y a des dossiers ou des films ou d'autre images.
merci
cordialement

Sita
05-29-2009, 09:54 PM
hello jeanlulu
j'ais vu les images que tu as posté. et je voulais savoir qui l'a fabriqué
et si il y a des dossiers ou des films ou d'autre images.
merci
cordialement


Why are it allways the French speaking who use their own language in an English spoken forum :first:

frenchy
05-31-2009, 11:55 PM
Why are it allways the French speaking who use their own language in an English spoken forum :first:

hello, sorry my language is not very well, and i would like speak to jeanlulu.
because he is french.
but I'm very interesting to our vtol. do you have finish it?
have you other pictures?
thanks
bye

Jeanlulu
06-04-2009, 09:45 AM
Good evening gentlemen, few informations about my backpack helicopter, (BpH_Mk1.86). It's directly inspired onto the Mr. Schöffman backpack, (see video on youtube: personal helicopter)
My objectif is to make a more simple mecanics with less possible failures, easy to fly, to make and transport. A totaly DIY project.
In this time I generate all logical P/N for part list, part and assy drawing.
I work on frame definition, several parts is to be refined designe by stress calculs.
You can see a little illustration on:

http://issuu.com/jeanlulu/docs/bph_mk1.86

Tanks for your intest frenchy.
See you later.

ruxpin76
06-23-2009, 07:36 AM
Anyone making progress on their rotorcraft? I've found some good video on Mr. Shoeffmann's craft -- do a google(tm) search on "metacafe" and 'pocket helicopter" and you'll see a good vid.

For those of you that have used 'diff gears' for your co-ax assembly, how are you preventing the vertical gears from rotating around the shaft? Does a pin go all the way through your central post? Have you calculated how that reduces the strength? Just curious...

No updates on Spratt rotor -- still working on how to actuate the 'kaman flap' style 'rotoron'. :) Is that a new term?

ruxpin76
06-23-2009, 07:41 AM
Bonne chance, Jean. J'espere que ton machine ne te morir, et le meme pour moi aussi...

Now back to your regularly scheduled ENGLISH program...;)

Sita
06-23-2009, 09:40 AM
Bonne chance, Jean. J'espere que ton machine ne te morir, et le meme pour moi aussi...

Now back to your regularly scheduled ENGLISH program...;)


Voor mijn part lult iedereen maar raak in z'n eigen taaltje:whoo:met de Frans sprekenden voorop natuurlijk:lalala:

ruxpin76
06-23-2009, 07:31 PM
Sorry, Cita, not up on my (?) Dutch...

How is progress on your machine? I have a line on a $1000 Rotax 125, so that may become my new powersource...

Jeanlulu
06-27-2009, 12:33 AM
Hello, Hallo, Bonjour,

the attached files is not the last version, but the last is too far of
sorry for the bad definition, the limit in KB is too low the real plan is on 1:1 scale

have a good day

Rotor Rooter
07-22-2009, 09:44 AM
Maybe not 'back-pack', however the pilot is standing. :sorry:

PAM GROUP flying platform Gizio design (http://www.youtube.com/watch?v=vQ28wTQoq9w&NR=1)

tyc
08-12-2009, 06:36 AM
"BACKPACK" HELICOPTERS?

Maybe it's just me but I swear, I do not understand this fascination with "backpack" helicopters.

I know the concept has been around for quite a while but can someone explain to me why?

ejb

Jens
08-15-2009, 01:40 AM
:angel:"BACKPACK" HELICOPTERS?
Maybe it's just me but I swear, I do not understand this fascination with "backpack" helicopters.
I know the concept has been around for quite a while but can someone explain to me why? ejb
Right – there exist quite a fascination with "backpack" helicopters. Why? I too am not sure.

But (fantasy) "BACKPACK" HELICOPTERS, most often, are supposed to move you freely around with your body.
Almost as free, as a free spirit would move around.

The “fascination with "backpack" helicopters”, might have something to do with this dream or wish?

tyc
08-18-2009, 08:18 AM
... supposed to move you freely around with your body. Almost as free, as a free spirit would move around. The “fascination with "backpack" helicopters”, might have something to do with this dream or wish?


Perhaps you're right but I keep thinking, if and for any reason the "landing gear" fails ...

tyc

Eli-sir
09-12-2009, 06:25 AM
Hello Guys, I have a big problem! I don't understand how Mr. Shoeffman has made the coupling between the conical gears and the aluminium plate in his back-pack helicopter. In particular haw He has fixed the gears... with bolts?

Please help me!

Eli-sir
09-12-2009, 06:33 AM
1st: this is my idea to fix the gears. It's can be correct?

2nd: what is the correct position of the ball bearing? My idea is use 2 ball bearing 1 up and 1 down the rotor blade, but Mr. Shoeffman used only one of this and put it between the two plate that substain the rotor blade.

What do you think?

Thanks in advance for all the answer.

tyc
09-12-2009, 06:39 AM
... I don't understand how Mr. Shoeffman ... made the coupling ...


For what it's worth, that gearing shown in the jpg is IDENTICAL to that used with the plastic model of the "Pogo", a VTOL - which you can still buy.

tyc

Rotor Rooter
09-12-2009, 12:08 PM
The following 4 pictures were just received in an email. There was no text on the e-mail, just the pictures.
Anyone know anything about this helicopter?

http://www.unicopter.com/Temporary/Maria%20Evliatou_4_Smaller.gif
http://www.unicopter.com/Temporary/Maria%20Evliatou_5_Smaller.gif
http://www.unicopter.com/Temporary/Maria%20Evliatou_6_Smaller.gif
http://www.unicopter.com/Temporary/Maria%20Evliatou_4_(2)__Smaller.gif (http://www.unicopter.com/Temporary/Maria%20Evliatou_4_(2)_Smaller.gif)


Dave
_______________________________________

Eli-Sir,

It would appear that;

The small pinion gears are mounted on bearings and the bolt attaches them to a stationary mast.
The sprocket, lower rotor and lower crown gear are one unit mounted on a pair of bearings to the stationary mast.
The sprocket, upper rotor and upper crown gear are one unit mounted on a pair of bearings to the stationary mast

Jens
09-12-2009, 12:23 PM
Fantastic! Beautifully made :first:
Really about time someone successfully copied Franz Schoefmans machine :welcome:
Quite small props… hope it also can fly :plane:

Eli-sir
09-13-2009, 09:45 AM
For my BHP I chose the Simonini MINI 3 engine look here: http://www.simonini-flying.com/mini3_eng.htm

It has an high torque @6500 RPM: 4.08 kg/m, I supposed that the counter rotating rotors turn about at 1000-1200 RPM so the reduction ratio is about 6, in this condition the torque at the rotor is 4.08 x 6 = 24.48 kg/m (about 240 N/m). This for me is a big problem, because the gears between the two rotors must sustain this high torque, and I don't found any gears so strong. But I have another problem, probably greatest, how I can fix the gear to the rotor?

Thanks in advance.

Willmer


P.S. Rotor Rooter: the pictures are fantastic!!!

Jens
09-13-2009, 10:04 AM
Simonini MINI 3 (270cc) is probably a better choise as Rotax 125.

Get a big V-belt pulley made, and ad a support pulley - probably needed.

With chain drive you can easily have 6 in reduction. Maybe standard gocart chain will not work, because rpm are 3 times less = pull in chain 3x higher.
Or ad a second reduction with touth belt to take the bigger torque.

Eli-sir
09-13-2009, 10:51 AM
Simonini MINI 3 (270cc) is probably a better choise as Rotax 125.

Get a big V-belt pulley made, and ad a support pulley - probably needed.

With chain drive you can easily have 6 in reduction. Maybe standard gocart chain will not work, because rpm are 3 times less = pull in chain 3x higher.
Or ad a second reduction with touth belt to take the bigger torque.

My idea is replace poly-v system with chain drive. I have already bought a little pinion gear for the engine, chain and all the materials necessary for the transmission, iron bar (39NiCrMo3) for the static shaft, ball bearing, Ivoprop rotor blade (1 left and 1 right), aluminum (2024 T351) is ordered and coming soon... Tomorrow I will make some photos...
With your help I hope to solve the problem of gears between the two rotors.
I live in Italy, at about 300 Km from Austria, If I knew the address of Mr. Shoeffman...:plane:

Willmer

Jens
09-13-2009, 11:00 AM
... I hope to solve the problem of gears between the two rotors...Willmer
Do it quite similar to Franz Schoefman, and throw away the calculations that say it can't work :D

Rotor Rooter
09-13-2009, 12:06 PM
Willmer [Eli-sir],

Number 2 [Mr. Shoeffman's] is the better arraignment, because;
It is simpler.
It is lighter.
The double row bearings will not be opposing each other due to axial loading.


Look up a bearing manual on the internet. There will be a section showing how to mount the bearings.

Dave

Eli-sir
09-14-2009, 12:51 AM
Dave (Rotor Rooter), in my post #290 I have attached two pdf files: "caso1" represents my idea, two ball bearings for each rotor, one upper the rotor and one lower the rotor. "caso2" represents the Mr. Shoeffman solution, only one ball bearing between the plates that substain the blades.

For you what is the best solution? I have available more SKF two row bearings type 3206.

Thanks

Willmer

Monte55
09-14-2009, 04:20 AM
Where has anyone seen pictures of the internal parts of Schoeffman rotor head? I followed him as far as the exterior but the internal parts, bearings etc, I had to figure out on my rotor head. Can someone share the Schoeffman pics?
Nick

tyc
09-14-2009, 06:56 AM
Autorotation ...

All the above is very interesting but when you have a moment, tell me about autorotation with such a design . . .

tyc

Jens
09-14-2009, 08:09 AM
Autorotation ...
All the above is very interesting but when you have a moment, tell me about autorotation with such a design . .
YES, all the above is very interesting :D

BUT it is important to understand, that we mean low and slow when we say low and slow.
Low = less than 6ft / 2m
Slow = as a bicycle - for a Franz Schoefman type of hovercopter.
Slow = as you walk – for Nick’s type of hovercopter.

Most talk about flying as a normal heli, incl. autorotation etc., with a so called “Backpack heli” is fantasy – and nothing wrong with that.
When not fantasy, it is a VERY different game, and NOT a hovercopter anymore, but a helicopter.

My opinion.

brett s
09-14-2009, 09:32 AM
Have an engine failure at 6' & walking speed in one of those & you'll be laying on the ground with it slammed on top of you.

Jump off a 6' wall wearing that much weight on your back & you may understand a bit better...

MikeUSA777
09-14-2009, 05:05 PM
Hello All ................ For Eli-Sir, I have a pretty good start on my Schoffmann-copter project. If you like, private message me and I'll send you everything I have done thus far. It might help you further in your plight. I'm in process of having my rotor head built now - based on a design by monte55.

Sita
09-15-2009, 12:23 AM
Have an engine failure at 6' & walking speed in one of those & you'll be laying on the ground with it slammed on top of you.

Jump off a 6' wall wearing that much weight on your back & you may understand a bit better...

Brett,

you are a very knowledgeable man beyond any doubt when it comes to terms of rotorcraft,but sometimes you're talking BS like most of us do from time to time.
You are comparing an engine failure at 6 ft height with a Schoeffman type heli,with jumping from a 6ft wall with the same weight on your back.
So I guess you assume that with an engine failure the rotors are stop turning in a split second.That would be an explosion from stored energy.
I think that any modern helicopter hovering in the "dead men's zone",which has to deal with the same condition you mention,engine failure with immediate halt of the turning rotor(s),the result would be not much different.
Schoeffman is "flying" his contraption for years without any accident.It could be though that he never had an engine failure but than the myth of unreliable two-stroke engines is busted.
Just like in any helicopter,Schoeffman has an over running clutch which gives the pilot a few seconds to go in autorotation,or in Schoeffmans case,to set the machine on the ground being only a few feet in the air anyhow.


I have met Mr. Schoeffman and have seen him flying his contraption and I can assure you that he's anything but a recless person.

If the Schoeffman heli is not your kind of thing than you have every right to express this but try to keep the BS out of the discussion.

Cita

Vance
09-15-2009, 02:03 AM
Brett,

you are a very knowledgeable man beyond any doubt when it comes to terms of rotorcraft,but sometimes you're talking BS like most of us do from time to time.
You are comparing an engine failure at 6 ft height with a Schoeffman type heli,with jumping from a 6ft wall with the same weight on your back.
So I guess you assume that with an engine failure the rotors are stop turning in a split second.That would be an explosion from stored energy.
I think that any modern helicopter hovering in the "dead men's zone",which has to deal with the same condition you mention,engine failure with immediate halt of the turning rotor(s),the result would be not much different.
Schoeffman is "flying" his contraption for years without any accident.It could be though that he never had an engine failure but than the myth of unreliable two-stroke engines is busted.
Just like in any helicopter,Schoeffman has an over running clutch which gives the pilot a few seconds to go in autorotation,or in Schoeffmans case,to set the machine on the ground being only a few feet in the air anyhow.


I have met Mr. Schoeffman and have seen him flying his contraption and I can assure you that he's anything but a recless person.

If the Schoeffman heli is not your kind of thing than you have every right to express this but try to keep the BS out of the discussion.

Cita

Hello Gilbert,

In my experience if you are at flight pitch in a helicopter and the engine stops the rotor slows down very quickly unless you lower the collective immediately.

I feel that the very small diameter blades on the coaxial one man helicopter would slow down very quickly.

One of the maneuvers you practice in a helicopter is engine outs at 5 feet agl in a hover so any experienced helicopter pilot is very familiar with what this is like and they are able to pull collective to cushion the impact. You do not have that option with the one man coaxial helicopter.

Stanly Hiller spoke to me at length about the challenge of rotorcraft without collective pitch and their limitations before he passed away. He explored this carefully with his flying platform and that is a part of why he abandoned the concept.

Anyone who has flown a gyroplane knows how rough the landing is if you flair six feet too high and you run out of airspeed before you run out of altitude. The large rotor is already pitched for autorotation.

I think it is nice of Brett to speak up when someone is discussing something that in his opinion based on his experience has risk that is being extolled as safe.

It appears to me that you are the one developing theories without experience. Is this what you mean by BS?

I am glad to find out that the myth of unreliable two stroke engines has been busted.

It is nice that Mr. Shoeffman hasn’t been hurt by an engine failure. How many hours do you think he has flown? Do you feel that is enough experience to pronounce the aircraft safe?

Thank you, Vance

brett s
09-15-2009, 04:03 AM
I think a lot of people look at these things & only see a fun toy.

How long does an aircraft prop keep spinning when the engine fails & you don't have any airspeed to drive it? These things are much closer to a prop than a helicopter rotor in terms of size & inertia.

In a conventional helicopter with far more rotor inertia an engine failure from 6' with no pilot intervention on the collective is usually going to break something (in a few types you'll probably write the airframe off!) - why do you think a small fixed pitch "backpack" helicopter will fare better?

Sita
09-15-2009, 05:23 AM
I think a lot of people look at these things & only see a fun toy.

How long does an aircraft prop keep spinning when the engine fails & you don't have any airspeed to drive it?

for the Schoeffman heli you seem to give exactly zero seconds Brett because the sinking speed equals the drop speed of the same dead mass faling from the same height.

These things are much closer to a prop than a helicopter rotor in terms of size & inertia.

]Nobody ever claimed they aren't[/B]

In a conventional helicopter with far more rotor inertia an engine failure from 6' with no pilot intervention on the collective is usually going to break something (in a few types you'll probably write the airframe off!) - why do you think a small fixed pitch "backpack" helicopter will fare better?

Brett you obviously are not in favor of this concept for reasons you think are valid enough for you and you have every right to do so.
Schoeffman is in his late 60's and has as far as I know no whish to end his life early by experimenting with things he considers dangerous beyond what is accepted.It might be that his perception of danger differs from yours or mine but this doesn't make him a fool like some like to let shine through.

Sita
09-15-2009, 05:25 AM
Hello Gilbert,

In my experience if you are at flight pitch in a helicopter and the engine stops the rotor slows down very quickly unless you lower the collective immediately.

I feel that the very small diameter blades on the coaxial one man helicopter would slow down very quickly.

One of the maneuvers you practice in a helicopter is engine outs at 5 feet agl in a hover so any experienced helicopter pilot is very familiar with what this is like and they are able to pull collective to cushion the impact. You do not have that option with the one man coaxial helicopter.

Stanly Hiller spoke to me at length about the challenge of rotorcraft without collective pitch and their limitations before he passed away. He explored this carefully with his flying platform and that is a part of why he abandoned the concept.

Anyone who has flown a gyroplane knows how rough the landing is if you flair six feet too high and you run out of airspeed before you run out of altitude. The large rotor is already pitched for autorotation.

I think it is nice of Brett to speak up when someone is discussing something that in his opinion based on his experience has risk that is being extolled as safe.

It appears to me that you are the one developing theories without experience. Is this what you mean by BS?

I am glad to find out that the myth of unreliable two stroke engines has been busted.

It is nice that Mr. Shoeffman hasn’t been hurt by an engine failure. How many hours do you think he has flown? Do you feel that is enough experience to pronounce the aircraft safe?

Thank you, Vance

Whatever you say Vance.

Jens
09-15-2009, 07:06 AM
If 6 ft is too dangerous for anyone – go only 3 ft high.
If full speed in your car, or on your motor bike, is too dangerous for you – go half speed.

WHAT’S THE PROBLEM :D

brett s
09-15-2009, 07:51 AM
As long as you are aware of the risks, it's not a problem at all.

Adults can make their own informed decisions, as long as you're not endangering others who cares!

But you at least need to consider all consequences - ignoring stuff doesn't make it go away.

C. Beaty
09-15-2009, 08:38 AM
There are photos of Igor Bensen flying a device that amounted to nothing more than a pair of Mac engines and a sawhorse; an engine at each end blowing air downward with Bensen seated in the center. It was controlled by vanes in the propeller slipstreams.

There used to be a Sunstate Rotor Club member, Bob Farmer from South Florida, who was the test pilot for a H2O2 powered tip jet project in Texas.

There was a backpack version that Bob flew briefly. His concern was that with one stumble, he’d end up in the center of an aluminum ball.

Wherever one goes in this World, there is someone brave enough or foolhardy enough to try to fly anything.

Jens
09-15-2009, 12:44 PM
Enjoy:

http://www.youtube.com/watch?v=aWG-rq8X1Mg

http://www.youtube.com/watch?v=BmuXTzU8-jM

Jens
09-20-2009, 01:35 AM
For hovercopters with fixed rotor blades or props:

1. Schoefman type with low inertia co-ax props - safer than most aircrafts :peace:
Would also be reasonable safe with low inertia co-ax rotor.
But with high inertia co-ax rotor, safety may only be marginally okay.

2. Heli frame type (as Nick’s) with low inertia co-ax props - safety marginally okay.
Heli frame type with low inertia co-ax rotor - safety might still be marginally okay.
But this type with high inertia co-ax rotor - safety may marginally not be okay.

3. All backpack types - much too dangerous.

One picture of low inertia props.
And one picture of a much too dangerous backpack heli.

Sita
09-20-2009, 04:20 AM
Jens,

what's the difference between Nick's machine and the Seremet,beside the rotor configuration regarding safety?
Both have rotor RPM change to replace collective and rotor tilt to replace cyclic.

Cita

Jens
09-20-2009, 05:13 AM
Seremet's machine is on your back at start and landing. Body legs is main or only landing gear :eek:
Test it. Take a person, 150lb, on your back. Jump from 1 or 3 ft height - and I think you at once will understand how (almost) impossible it is to handle that much load on your back. And in this test you don't have a spinning rotor on top of your head that might have sufficient energy to kill you.

In Nick's machine, the body is fixed to the heli frame. All load at start and landing goes into the heli frames landing gear.
The problems here are different. This machine, with even a minor forward speed and an uneven terrain - he and the hole thing will tumble! He can do nothing or very little with his legs, because it will immediately ruin the balance of the hole machine.

Do you agree?

Rotor Rooter
09-20-2009, 09:11 AM
What about an electric backpack where the motors cannot fail?

brett s
09-20-2009, 10:55 AM
Not possible - there's always a way for one to fail. It's possible to have an electric system far more reliable than a gas engine of course, but don't kid yourself that it's 100% reliable.

Magnets can come loose & cause a motor to seize, wires can come loose, controllers & batteries can fail. If you hang out around the electric r/c crowd you'll see all of the above sooner or later.

Rotor Rooter
09-20-2009, 11:09 AM
Not possible - there's always a way for one to fail.
You are correct. The comment was too short and too strong.

It's possible to have an electric system far more reliable than a gas engine ......

Your above comment is a better one.

Dave

Sita
09-21-2009, 12:47 AM
Seremet's machine is on your back at start and landing. Body legs is main or only landing gear :eek:
Test it. Take a person, 150lb, on your back. Jump from 1 or 3 ft height - and I think you at once will understand how (almost) impossible it is to handle that much load on your back. And in this test you don't have a spinning rotor on top of your head that might have sufficient energy to kill you.

In Nick's machine, the body is fixed to the heli frame. All load at start and landing goes into the heli frames landing gear.
The problems here are different. This machine, with even a minor forward speed and an uneven terrain - he and the hole thing will tumble! He can do nothing or very little with his legs, because it will immediately ruin the balance of the hole machine.

Do you agree?

Hello Jens,

where do you get the 150 lb comparison number from? The Schoeffman heli is roughly 70 lbs and I don't know how much Nick's machine is.
The WS-12 is roughly 110 lbs.
If I have the choice between jumping from 3 feet heigh with the 70 lb Schoeffman on my back or sitting in a hard bottom plastic/metal seat and be dropped from 3 feet,I think I'll go for the Schoeffman.
With no wheels on the landing gear,the chances that Nick's machine is tumbling during minor forward speed landing are also existing with the same result.If Seremet's rotor has enough kinetic energy to kill you than Nick's rotors have probably the same ability to do this.

Any idea how many birds would survive their first flight if they would have a fixed landing gear instead of their flexible legs?
Try to imagine how complex a helicopter landing gear would be if we wanted it to be able to land under the same conditions as birds can do.
Almost any ten year old child has a thousand times more walking stability than the latest super computer guided walking robot,in fact the performance of the multi million dollar walking robot is redicilous compared to that of any normal child.

What would the result to the human body be when one is dropped from 10 feet heigh with a 70 lbs back-pack on his back and what would the result be on a person,sitting in Nick's frame for example,dropped from ten feet heigh?
I guess the first one will probably suffer lower body damage,the latter probably spline damage,your choice to pick Jens.
I don't know how many ejection seat emergency escapes a fighter pilot can do before he fail his medical but I gues they aren't too many.This in a specially designed seat to absorb the sudden schock.The load the spline receives in the ejection seat may be much more than the 10 feet drop example but it's just to show that it's not because you're in a seat that your protected from everything.The energy has to go somewhere and maybe our legs are better designed to do this than our back and butt !!

Cita

Jens
09-21-2009, 07:43 AM
Cita,

You could handle a backpack type of 70lb safely, but not a 150 lb backpack type – right?

I know that 70 lbs are typically for a paramotor, and I have a lot of experience with that load on my back – but not with a 30hp rotor/props over my head.
I know Nick has written 167lb.
I know there is no typycal weight for a backpack heli - because none are flying.
I know a Mosquito is 254lb.
I know Vincent Seremet today has a big laugh about his backpack contraptions, and he have told me, they where somewhere between impossible or almost impossible to control and handle. And he has a strong body which he is very able to use.
He more than once ended up in a funny situation – also told with a big laugh :D

Much better if you yourself ask Vincent, how safe he thinks “backpack type heli’s” are.
You can get his phone number here: www.degulesider.dk/ Just put his name in the first window and press enter and put 0045 in front of the number.

I guess he don’t mind having a talk with you.

Rotor Rooter
09-21-2009, 08:36 AM
This is the weight and balance (http://www.unicopter.com/S_II_WeightAndBalance.html) for the complete two motor version of the SynchroLite, as shown below. Much of which will not be required for a backpack.

This is the weight of one blade, which is 8-ft long (http://www.unicopter.com/0672_BOM.html).
This is the weight of one complete rotor, with a pair of blades. (http://www.unicopter.com/0692_BOM.html)

The calculations were worked out quite accurately.

Add a light electric motor (or two) http://www.unicopter.com/ThumbsUp.gif plus the gimbal rotor frame and the total overhead weight becomes .......

http://www.unicopter.com/0748_1.jpg

http://www.unicopter.com/PowerTrain_Picture3.jpg

Sita
09-21-2009, 11:26 AM
Cita,

You could handle a backpack type of 70lb safely, but not a 150 lb backpack type – right?

I know that 70 lbs are typically for a paramotor, and I have a lot of experience with that load on my back – but not with a 30hp rotor/props over my head.
I know Nick has written 167lb.
I know there is no typycal weight for a backpack heli - because none are flying.
I know a Mosquito is 254lb.
I know Vincent Seremet today has a big laugh about his backpack contraptions, and he have told me, they where somewhere between impossible or almost impossible to control and handle. And he has a strong body which he is very able to use.
He more than once ended up in a funny situation – also told with a big laugh :D

Much better if you yourself ask Vincent, how safe he thinks “backpack type heli’s” are.
You can get his phone number here: www.degulesider.dk/ Just put his name in the first window and press enter and put 0045 in front of the number.

I guess he don’t mind having a talk with you.

Jens,

the 70 lbs figure is from the Schoeffman heli,not a paramotor.
I visited Seremet a few years ago in Greve Strand where he lives and unless something has changed,I wont be able to communicate properly with him cause he only speaks Danish and probably another Scandinavian language but no German or English.
Luckely the Flemish dialect I speak made it possible for me to understand a little bit.I bought his DVD and his book.
I can imagine that he laughed about his back-pack helicopters because his first machine didn't even had a tailrotor to counteract torque but a fixed rudder !! Wonder why he spinned around at nearly take-off .
Secondly,the only picture I know off of a back-pack helicopter hovering in the air is from Seremet but he used body weight shift to control the heli which would have been akward because the pilot is strapped into the frame with little body movement possible.
The tail rotor on this machine had a fixed pitch so that probably didn't help either to control the machine.
His rotor had no hinges whatsoever so even the slightest gust would have give some problems.

40 years ago the US was able to let a man walk on the moon and everybody says that today it's not possible to design/build a back-pack helicopter ?
In fact what they are saying is technology wise mankind has gone backwards ?

I agree that a workable back-pack helicopter is probably not going to be developped by the homebuilder but that's not the same as "it is not possible".

Cita

Sita
09-21-2009, 11:34 AM
[QUOTE=Rotor Rooter;319371]This is the weight and balance (http://www.unicopter.com/S_II_WeightAndBalance.html) for the complete two motor version of the SynchroLite, as shown below. Much of which will not be required for a backpack.

This is the weight of one blade, which is 8-ft long (http://www.unicopter.com/0672_BOM.html).
This is the weight of one complete rotor, with a pair of blades. (http://www.unicopter.com/0692_BOM.html)

The calculations were worked out quite accurately.

Add a light electric motor (or two) QUOTE]

Dave,

thanks for the figures,very interesting !!

What about the Baumgartl intermesshing back-pack helicopter,the one with the single blade rotors that used the engines as a counter weight?
Perhaps electric motors would shed a new light on this design?

Cita

brett s
09-21-2009, 11:39 AM
More along the lines of "not practical" & "not very safe" than "not possible".

Those add up to "no commercial viability", so you're left with only die-hard homebuilders messing around with them.

HobbyCAD
09-21-2009, 12:00 PM
More along the lines of "not practical" & "not very safe" than "not possible".

Those add up to "no commercial viability", so you're left with only die-hard homebuilders messing around with them.

Brett, PERFECTLY SAID !!! Man, I love flying contraptions, but some things are simply just OTT !! I have respect for the die-hard homebuilders tinkering with backpack machines, but why don't they direct their energy at building a conventional machine. It's like recumbent bicycle or unicycles, yes, they are functional, but all that effort, for little or no gain, just to be different? To me, the idea of a backpack heli is like building a Ferrari without an engine, with pedal power, just to save fuel. Sure, it can be done, but what for?

Francois

Sita
09-21-2009, 12:20 PM
More along the lines of "not practical" & "not very safe" than "not possible".

Those add up to "no commercial viability", so you're left with only die-hard homebuilders messing around with them.

Brett,

we could argue till the end of times but what is the commercial viability of a gyrocopter or the practicallity of it ? I agree that it's a safe machine to use but other than fun it has little value.How many have tried to give the gyrocopter a place in the commercial aircraft scenery?
I think there is enough technology available to make an "acceptable safe" back-pack helicopter.
The Wright brothers messed around,Bensen messed around and so did Sikorsky,Kaman and many others in their early times,all die-hard people I guess.

Cita

Sita
09-21-2009, 12:29 PM
Brett, PERFECTLY SAID !!!.....I have respect for the die-hard homebuilders tinkering with backpack machines, ......To me, the idea of a backpack heli is like building a Ferrari without an engine, with pedal power, just to save fuel.......?

If at first an idea does not sound absurd,than there's no hope for it
Francois

you have to make up your mind Francois

Jens
09-21-2009, 12:48 PM
...the 70 lbs figure is from the Schoeffman heli,not a paramotor.
I know that. I mention that to tell you, that I know what it means to have 70lb on my back in a somewhat but much less challenging situation.

1. A Schoefman type you don’t have on your back.
2. A heli frame type as Nick’s, you don’t have on your back.
3. A backpack type you have on your back.

A backpack type might be safe in many places, but not on a heavy gravity planet like planet earth.

Rotor Rooter
09-21-2009, 02:34 PM
What about the Baumgartl intermesshing back-pack helicopter,the one with the single blade rotors that used the engines as a counter weight?
Perhaps electric motors would shed a new light on this design?

Cita,

Something like this. Single-Bladed All Electric Rotor (http://www.unicopter.com/ElectroRotor.html) ;)

Apparently the single-blade rotor works well for vertical flight but it cannot handle the dissymmetry of drag during forward flight.


Brett & Francois

Ideas build upon previous ideas.

I've looked at just about every conceivable type of rotorcraft configuration there is. It began to appear that God never intended for rotating airfoils to fly radially through the air. That caused the start of this project (http://www.unicopter.com/AeroVantage.html).

The backpack didn't look too good a couple of years ago, however two things have changed my thinking.

~ 1/ It appears that a large precone may overcome any lack of speed stability.
~ 2/ However, the really big advantage is the implementation ofhttp://www.unicopter.com/Lightning.gif Electric drives http://www.unicopter.com/Lightning.gif.
Few would say that the thousand of parts on a conventional helicopter are safer than the few parts on an electric backpack with a reliable motor and controller. Therefor 30 seconds of emergency power during the landing will keep the weight off of the pilot's back until his feet are firmly planted. Then he can reduce the power and squat to place the tripod on the ground.


Dave

Sita
09-21-2009, 08:03 PM
I know that. I mention that to tell you, that I know what it means to have 70lb on my back in a somewhat but much less challenging situation.

1. A Schoefman type you don’t have on your back.
2. A heli frame type as Nick’s, you don’t have on your back.
3. A backpack type you have on your back.

A backpack type might be safe in many places, but not on a heavy gravity planet like planet earth.

Jens,

Schoeffman uses the bicycle seat only in flight.During take-off and landing he's using his legs and he "wears" the helicopter on his back/shoulders.

Sita
09-21-2009, 08:05 PM
Dave,

thanks for the figures,very interesting !!

What about the Baumgartl intermesshing back-pack helicopter,the one with the single blade rotors that used the engines as a counter weight?
Perhaps electric motors would shed a new light on this design?

Cita

Dave I meant the Baumgartl co-axial of course,not intermesshing.

Eli-sir
09-21-2009, 09:53 PM
Guys look this:
http://www.youtube.com/watch?v=KlKSDPBSBmU
it's only just for fun... this is our Italian fantasy! In my slang we say "robe fora de posto", it is read and pronounced as it is written and means "things out of place", it is used to define a crazy situation.

Willmer

Rotor Rooter
09-21-2009, 10:04 PM
Dave I meant the Baumgartl co-axial of course,not intermesshing.

Hi. These appear to be the rotorcraft that Baumgartl produced;
Baumgartl Heliofly I (http://www.aviastar.org/helicopters_eng/baumgartl_heliofly-1.php)
Baumgartl Heliofly III-57 (http://www.aviastar.org/helicopters_eng/baumgartl_heliofly-357.php)
Baumgartl Heliofly III-59 (http://www.aviastar.org/helicopters_eng/baumgartl_heliofly-359.php)

An Austrian gentleman who lives nearby has been building model helicopters for decades trying to find a new and workable concept for a ultralight personal helicopter. His last model consisted of a large propeller at each end of an arm that rotated about the mast. The large propellers were tilted so that they would provide lift and also rotate this arm about the mast.
At 90-degrees to the arm was a large teetering rotor and it was driven around the mast by the arm with its large propellers. The teetering rotor was to provide lift, as well as provide autorotation if needed. Unfortunately the two large propellers provided better lift then the combination of all three.

He has gone back and is building a coaxial single-blade model helicopter with the electric motor as the counterweight of the lower single-blade rotor. The upper blade is driven from the lower rotor by a crown gear, to pinion gear, to crown gear and the 3-gear assembly is free to rotate around the mast. The upper rotor is removable so that he can test all sorts of blade configurations on the upper rotor. It is not yet flying.

Dave

Sita
09-22-2009, 12:32 AM
Hello Dave,

I meant the Heliofly-57

Cita

Eli-sir
09-22-2009, 01:04 AM
An Austrian gentleman...

...He has gone back and is building a coaxial single-blade model helicopter with...

Dave have you some photos of this helicopter or internet site address?

Thanks

Willmer

Jens
09-22-2009, 08:13 AM
More along the lines of "not practical" & "not very safe" than "not possible".
Those add up to "no commercial viability", so you're left with only die-hard homebuilders messing around with them.
Don’t let you be disturbed by that. It will never end.
The challenge here, as well as everywhere else, is to learn, understand and get something done anyway.

One person has build a workable and safe machine in the homebuild hovercopter category. And proven it succesfull beyond any doubt.
How many have interest in such a machine? Not many – same for gyro and even PPG. We are all very few – yet :)

Rotor Rooter
09-22-2009, 09:22 AM
Dave have you some photos of this helicopter or internet site address?

Willmer,

He does not use the computer.

Here is a picture of the model mentioned above and a previous one. The model of the single-bladed coaxial is still 'under construction'.

http://www.unicopter.com/Temporary/Hans_1.jpg

http://www.unicopter.com/Temporary/Hans_2.jpg

Dave

Jens
09-22-2009, 01:19 PM
Brett, PERFECTLY SAID !!! Man, I love flying contraptions, but some things are simply just OTT !! I have respect for the die-hard homebuilders tinkering with backpack machines, but why don't they direct their energy at building a conventional machine. It's like recumbent bicycle or unicycles, yes, they are functional, but all that effort, for little or no gain, just to be different? To me, the idea of a backpack heli is like building a Ferrari without an engine, with pedal power, just to save fuel. Sure, it can be done, but what for? Francois
Know and understand that there are no backback heli’s, and there have never been a backback heli - flying.
All build backback heli’s have been unworkable, uncontrolable and dangerous. Backback heli is mainly fantacy.

With all flying helicopters, you put your body on a heli frame – you never put the heli frame on your back!
Obviously that is too heavy, too uncontrollable and too dangerous.

But workable, controllable and safe flying hovercopters can be build :peace:. Unfortunately they still get mixed up with backpack heli’s.

Sita
09-23-2009, 02:38 AM
[QUOTE....Backback heli is mainly fantacy.....QUOTE]


When the Wright brothers started their work,flying an aeroplane was mainly fantasy.
When Sikorsky started work on his first helicopter,flying a helicopter was mainly fantasy.
When Wendell More started to think about the Bell rocket belt,flying a rocketbelt was mainly fantasy,heck even JFK was using his fantasy when he declared that the US would bring a man to the moon !!!

Every idea starts as a fantasy Jens !!

The back-pack helicopter would be a fantasy if it would be technically impossible to design/devellop such a machine.

I think we all agree that with our modern technology building a safe back-pack heli is feasable,question is:can we find the right reason to spend the money-time and effort to justify this ?

We can forget about the "die-hard" homebuilder as being the first one to devellop a safe back-pack helicopter,they usually don't have the means-technology-logistics to do this but.....idea's are costing nothing and perhaps it's one of those die-harders who can come up with the right idea.

Technical evolution will NEVER stop,it's mankinds nature to search for new challenges only.....times are starting to change into the direction that people are being told NOT to experiment and NOT to build new things for the sake off...safety.
Millions of people have been killed in car accidents,ok we can live with that but the one experimenter who kills himself in a homebuild gyroplane is the news item of the day.If he happens to take a bystander with him than he becomes a murderer.
The worldwide hunger for a nanny state will kill the inventive mind of John Doe.

(Rant over,grin-grin)

Cita

Jens
09-23-2009, 07:11 AM
…Every idea starts as a fantasy Jens !!…..Cita
I have NOT said that fantacy is wrong.
Fantacy flying backpack helicopters are fine.
Fantacy flying elephants are fine.
Etc. etc..
AS LONG AS ONE KNOW IT IS FANTACY.
__________________________________________________

….. I think we all agree that with our modern technology building a safe back-pack heli is feasible…..Cita
NOT in this group.
Allmost all here agree that a helicopter on your back is obviously too heavy, too uncontrolable and too dangerous.
__________________________________________________


A hat helicopter might be easier to build, as you get rid of the unsolvable out of ballance problem.
Just pay no attention to the weight of the thing, as you do for the backpack heli, and everything is fine - right..

Rotor Rooter
09-23-2009, 01:08 PM
NOT in this group.
Allmost all here agree that a helicopter on your back is obviously too heavy, too uncontrolable and too dangerous.

1/ The rotors with their small diameter and very rigid blades must provide a much faster response than teetering rotors.

2/ A large precone angle should provide static stability (http://www.unicopter.com/B329.html#Static_Stability).

An electrically driven backpack offers several previously unobtainable advantages.

3/ Emergency power during the landing will keep the weight off of the pilot's back until his feet are firmly planted. Then he can reduce the power and squat to place the tripod on the ground.

4/ The counter-rotating rotors have little rotational inertia. Using the motor as a brake upon landing would quickly slow their rotation, without a reaction on the tripod or pilot.

5/ The heaviest weight, other than the pilot, will be the battery pack and it is down with the pilot and assisting in the weight-shifting.
The 'objective' for a worst case scenario would be: The tripod tips over, the pilot falls over, the pilot gets dirty.


http://www.unicopter.com/0812_D.gif

Dave

Sita
09-23-2009, 01:15 PM
Jens,

you do respond to my reply's but do you actually read and understand them?

Where did I state that it was someone from this group who would build the first practical back-pack heli?
The only thing I said that was perhaps a homebuilder could come with a good idea.

If you think that there's not enough knowledge and technology available today to build a safe back-pack helicopter than you're running far behind mate !!!!


Cita

Sita
09-23-2009, 01:19 PM
Dave,

interesting stuff !!!

keep it coming !!!

Thanks,

Cita

Rotor Rooter
09-23-2009, 01:47 PM
Who would be flying gyrocopters today if they could not buy their rotor-blades from outside sources?

Who would be flying gyrocopters today if they could not buy their engines and from outside sources?

Who will be flying gyrocopters tomorrow when they can buy their blades and electric motors for backpack (and ultralight) helicopters from outside sources?


Should this post have been hidden on the Helicopter thread? :o

Mild Bill
09-23-2009, 11:20 PM
It's like recumbent bicycle or unicycles, yes, they are functional, but all that effort, for little or no gain, just to be different?Unicycles aren't functional except for showing off a keen sense of balance. Recumbent bicycles, on the other hand, are functional in ways that offer a great deal of gain. There isn't any better kind of recreational road bike.

Recumbent advantages:

1) The one that trumps everything else for the vast majority of bicycle riders: Comfort.

Let's face it, the standard bicycle is nothing but a medieval torture device: numb hands from resting part of your weight on the handlebars, numb butt from resting most of your weight on a narrow saddle seat, stiff and sore shoulder and neck muscles from constantly holding your head up to see forward. Recumbents are illegal in most bike racing, so professional bike racers put up with the discomfort of standard bikes to earn a living. Who's paying you to endure the torture?

Yes, I know about padded seats and padded gloves. None of them ever prevented me from suffering numbness after an hour or so. And I defy anyone to say that the typical rider of a standard bike doesn't suffer from sore neck and shoulder muscles on long rides. When I took my recumbent on century (100 mile) rides, I would look around after about 20 miles and see practically all riders on standard bikes hanging their heads down, studying the pavement or the rear wheel of the rider ahead. What the hell good is any ride on the road if you can't enjoy the scenery? Me, I would be in a comfortable position, always aware of the events on the road well in front of me, even while gazing around at the scenery.

Little or no gain? Pish posh.

2) Speed.

The recumbent/rider combination presents less aerodynamic drag than the standard road bike/rider combination. Only the specialized racing bikes with vertical seat tubes, severely dropped handlebars, and rider leaned over so far that his back is parallel to the ground or even sloping down toward the front can match a moderately low recumbent (nothing can match the freakishly low recumbents). Those racing bikes perpetrate even more hideous torture on their riders, even when they're resting their forearms on forward handlebar extensions. Again, if you're riding a racing style bike so you can be at the front of your club ride or king of the bike path, who's paying you to put up with the insult to your body?

Little or no gain? Pish posh.

3) Braking.

Hit the brakes hard on a regular bike and you get a weight transfer toward the front wheel due to deceleration force. If you're not careful on the front brake lever you can end up pitching over the handlebars due to the high center of gravity. And what's the first thing that hits the ground if you go over the handlebars? Your head.

Of course, you still get a weight transfer forward on a recumbent, but thanks to the lower center of gravity you won't go ass over teakettle - you'll just stop quicker because not pitching over allows you to apply more braking force to the front wheel.

Little or no gain? Pish posh.

4) Other safety considerations.

Suppose your front wheel starts sliding around on some gravel or wet leaves, or in a panic stop you manage to squeeze the brake lever hard enough to lock up the front wheel. On a regular bike you fall from a great height with a resultant high impact. On a recumbent, there's a lot less impact because you're falling from a lower starting point.

If you run into something substantial, your head arrives first if you're on a standard bike, your feet arrive first if you're on a recumbent. I'd much rather break my ankles than my skull or neck.

Little or no gain? Pish posh.



It's only fair to list the major recumbent disadvantages:

1) Mountain biking.

Some years ago I read a statistic that 75% to 80% of mountain bike owners never took their mountain bikes off regular streets and roads - they just wanted the softer tires (at the expense of higher rolling resistance) and slightly more upright position to escape some of the distress of the standard road bike. If you're one of the minority who do go off road and jump over boulders and logs, then a recumbent is definitely NOT for you.

Little or no gain? More like a major, devastating loss, but only for those who actually go off road.

2) Hill climbing.

Conventional wisdom has it that you can't climb a long steep hill as fast on a recumbent because you can't jump out of the saddle to get greater mechanical advantage on the peddles. I have to wonder about that - if it's mechanical pressure against the pedals you're seeking, you can push just as hard against the seat back as you want, so perhaps it's a matter of training and psychological adjustment to different techniques.

I've always been a "spinner" (high crank rpm's at low pedal pressure) rather than a "masher" (low crank rpm's at high pedal pressure). Spinners seem to have less need for jumping out of the saddle, and in any event I almost never jumped out of the saddle when climbing on a standard bike anyway, so I haven't seen any difference in climb rate.

Finally, it depends a lot on where you ride your bike. In my area, there are very few long steep hills, so again I don't perceive a significant disadvantage for a recumbent.

Little or no gain? Depends on how much you care about climbing to begin with, riding technique, and where you're located. For me it's a complete non-issue, but I'll grant that for some a recumbent could mean not only little or no gain but a small to moderate loss.



Now, as with a standard bicycle, the quality of your ride is going to depend a lot on the quality of the bicycle. There are a lot of bad recumbents out there. I've seen many that weighed as much as 50 lb (23 kg). Many have a very long wheelbase with bad steering geometry, making the handling slow and the steering effort like trying to turn a locomotive around by the headlight. What you need is a relatively light weight recumbent with correct front end geometry and a wheelbase and front/rear weight distribution like a standard bike, which is best realized by a bike with the front wheel behind instead of in front of the feet.

I bought my Lightning P-38 from Brummer Engineering in 1987 and will never go back to a standard bike. The company is now known as Lightning Cycle Dynamics (http://www.lightningbikes.com/), and the current P-38 is essentially though not exactly the same as mine.

Sorry to go into such detail on a digression, but I thought the readers should be exposed to another opinion rather than just concluding, "Oh, right, recumbents - not too good are they?" Au contraire, they are the best for the great number of recreational cyclists who stick to the roads, streets, and bike paths.

Jens
09-24-2009, 07:27 AM
Which body part to use to connect with a helicopter?

We have just covered bottom, shoulder, back and head – enough for me for now :D

Rotor Rooter
09-24-2009, 06:49 PM
Jens,

My two cents;

1/ The first requirement is having the rotor and the weight on opposite sides of the gimbal.

2/ The next requirement is providing rotors that have low inertia and high rigidity, so that the craft responds very quickly to cyclic and thrust commands.

3/ The last requirement is having an extremely high level of reliability in the power-train from fuel storage to moving the air.

A controlled landing then becomes a non-event.

________________________

It looks like Frans Schoeffman got it right. The front two rods control the rotor and the rear rod controls the weight.

As a secondary usage, these three rod provide a support so that he doesn't have to lay the craft on the ground.


IMHO, there is only one significant improvement that could be made. :D

http://www.unicopter.com/ElectricPlug.gif


Dave

Sita
09-25-2009, 02:21 AM
Dave,

perhaps that a great deal of the design concept of how an electric BPH should work has been done by the RC guys.
I'm certainly not an expert on electric,or any for that matter,RC heli's but it seems that these guys pretty much have everything under control.

It was once suggested to me to use the wings of a large scale RC glider as a mould to produce composite light weight rotor blades for a BPH.

Bearing in mind that Schoeffman seldom make flights that last longer than a few minutes at a time,store energy for the E-motors might be doable in regard of battery or cell weight for such short periods.

Cita

Rotor Rooter
09-25-2009, 08:36 AM
Cita,

You bring up excellent points.

perhaps that a great deal of the design concept of how an electric BPH should work has been done by the RC guys. This is a thread that was found last night. (http://www.rcgroups.com/forums/showthread.php?t=997243) It is the building of an Axial flux motor.

It was once suggested to me to use the wings of a large scale RC glider as a mould to produce composite light weight rotor blades for a BPH. In addition, here is another idea. Could IVOPROP ~ Quick Ground Adjustable Ultralight Prop (http://www.ivoprop.com/ultralightmodel.htm) serve for the backpack. Particularly since it may be possible to automatically use its pitch change with the motor's torque to give a 2-position pitch for powered flight and for autorotation.

This is a page on this idea. (http://www.unicopter.com/1763.html) It is a combining of the Axial Flux motor in the first link with pitch change in the second link.

Bearing in mind that Schoeffman seldom make flights that last longer than a few minutes at a time,store energy for the E-motors might be doable in regard of battery or cell weight for such short periods. Yes, and the battery weight will not be in the rotorhead.

Dave

http://www.speakwell.com/well/2003winter/graphics/participaction.jpg

Jens
09-25-2009, 08:56 AM
Here is a 290 lb helicopter that very easily can be modified to a BPH - as a few here prefer.
Just cut of the 3 tubes :)

Interesting video here, but sorry no sign of a BPH in it:
http://www.youtube.com/watch?v=Qh1SGnNte5Q

Rotor Rooter
09-25-2009, 10:07 AM
Some thoughts;

The good: The twin-rotor helicopter is the easiest helicopter to pilot.

The bad: The coaxial is the least efficient configuration, and this is a negative for current electric drives.

The thought: IF the rotorhead of the helicopter can give instantaneous response and IF the helicopter is totally reliable, the pilot can play touchy-feely with his feet and the ground all day without stumbling.

If outside perturbations are a stability concern, then consider that the exposed backpack pilot has a greater weight/drag ratio than the fuselage of any helicopter.

The provocative:
Has anyone heard of a pilot dying in a backpack rotorcraft?
Has anyone heard of a pilot dying in a 'normal' rotorcraft?

brett s
09-25-2009, 10:40 AM
Has anyone compared the numbers of "normal" helicopters to the number of successfully flown backpack ones?

How many total hours would you estimate all backpack helicopters combined have actually flown?

If the current gas backpack helicopters can barely get off the ground with only a few minutes of fuel, given the energy density of current battery technology you're probably looking at under a minute of flight time. The technology just isn't anywhere near where it'll need to be for that yet.

Jens
09-25-2009, 11:03 AM
For Rotor and Cita,

Sorry, again a picture of a man sitting on a helicopter and not the opposite – so to speak.
But look how easy that helicopter could be converted to at head helicopter. Or maybe both of you insist to wear them on your back?
Just cut 1 tube :yo:

For the rest of the readers - just for fun.
Something I maybe should not do :ohwell:

Rotor Rooter
09-25-2009, 11:38 AM
brett,How many total hours would you estimate all backpack helicopters combined have actually flown? Lets see now. 5 minutes x 150 flights = 12.5 hours total time??? ;)


Jens,Sorry, again a picture of a man sitting on a helicopter and not the opposite – so to speak.
But look how easy that helicopter could be converted to at head helicopter. Or maybe both of you insist to wear them on your back?
Sorry, that IS a backpack helicopter.

The ultralight regulations in Japan demand that a craft under a certain weigh must have foot landing.
Look at the landing in this video. http://www.youtube.com/watch?v=Hgn1Psq0V24 :lol:

Dave

Jens
09-25-2009, 11:57 AM
..Jens,Sorry, that IS a backpack helicopter...
Very clear as usual.
So, if the pilot can reach the ground with his feet, it is a BPH.
Maybe we already have a lot of BPH's and a lot of BPH-hours in the air :lalala:

Rotor Rooter
09-25-2009, 02:33 PM
Jens,So, if the pilot can reach the ground with his feet, it is a BPH.
Apparently.

When is Frans Schoeffman backpacking his helicopter? No joking.
http://www.youtube.com/watch?v=WHA8PlieHIg&NR=1
http://www.youtube.com/watch?v=1S0w1yYSwiI&feature=related
http://www.youtube.com/watch?v=BmuXTzU8-jM&feature=player_embedded
http://www.youtube.com/watch?v=aWG-rq8X1Mg&feature=player_embedded#t=26

For landing he reduces the power so that his feet can start to absorb HIS weight, he then reduces the power (which is still carrying a portion of his weight) until the supports are on the ground. His jockstrap belt never supports the craft.
______________________________

The GEN-H4 and Schoeffman's craft are basically identical, from a functional perspective, (small rigid rotors, weight shift-control, overhead motor). Nether the pilot of the GEN-H4 or Frans Schoeffman pack any of the craft's weight.

IMO, the electrification of Frans Schoeffman helicopter represents the entry point into the low-cost light-weight future.
______________________________

The term 'Backpack Helicopter' is a misnomer for today's and tomorrow's extremely light helicopters.

HOW ABOUT A CONTEST ON THIS FORUM TO SUBMIT AND VOTE ON THE NAME FOR TOMORROW'S EXTREMELY LIGHT HELICOPTERS.

Sita
09-25-2009, 10:58 PM
For Rotor and Cita,

......But look how easy that helicopter could be converted to at head helicopter. Or maybe both of you insist to wear them on your back?
Just cut 1 tube :yo:

For the rest of the readers - just for fun.
Something I maybe should not do :ohwell:

Jens,

this same BS was thrown at me as early as 4 years ago,and many had followed, in this same thread so you're not very original.

"Don't ever put yourself down,there are others waiting in line to do that for you,and usually are much better in it anyhow "

"Gerald Greenhow"

Jens
09-26-2009, 12:21 AM
... this same BS was thrown at me.....
Maybe they too where trying kindly to tell you the same thing as I am:
Wearing a helicopter (on your shoulder, back or head) is obviously too heavy, too uncontrolable and too dangerous.

As I don't think you are a low IQ person or crazy, what word(s) do you not understand here?
They are all commen english words. I have not used any of the words in any special meaning. So an ordinary good english dictionary can be used.

Rotor Rooter
09-26-2009, 10:39 AM
The conventional references to the helicopter pilot's controls are 'cyclic' and 'collective'.

For a craft that has both a gimbaled head and 'absolutely' rigid rotors, such as a backpack helicopter, these words are misnomers. This craft does not have a cyclic or collective control mechanism, such as the swashplate. In addition, there is no cyclic action taking place in the rotor because the rotor does not teeter, flap or lead-lag.

Perhaps this control system should be considered in the context of a Cylindrical Coordinate System (http://en.wikipedia.org/wiki/Cylindrical_coordinate_system). The cyclic then become the Direction (azimuth) and Tilt (angle, radius, radial distance) The collective then becomes the Throttle (thrust, force, magnitude)

Dave

Sita
09-26-2009, 10:55 AM
Jens,or Mother Theresa,or whatever you prefer,

go play the Nanny on another thread or start your own.


If you don't believe in the concept of the BPH,that's fine with me and you made your point more than clear,as did others, with images you think are funny.

You are certainly not on the top of the list of people who could pursuade me to abandon the BPH concept so stop waisting your energy on this.
If you like to save people than join the Salvation Army or the World Wide Nanny Society,I'm sure they appreciate people like you who's only goal is,seemingly, to prevent people from hurting themselves.

Cita

Rotor Rooter
09-26-2009, 01:01 PM
Here is an argument for "Deconstruction" (http://www.unicopter.com/1764.html#Weight_Ratio) i.e. increasing the ratio of payload weight to vehicle weight, while improving the reliability and easy of piloting, etc. This is particularly relevant to rotorcraft since they are probably the most inefficient and expensive vehicle there is.

Jens,

My thinking is to produce an electric 'backpack' that is as light, but reliable, as possible. The word 'economical' also plays a roll. This 'backpack' might then be tested remotely as a big model, and then as a manned craft.

Other could/would participate in build their own light and economical 'backpacks' and collectively learn from the group, just as the recreational gyrocopter did. During this process the motors and the rotors can be improved without necessarily increasing their mass or size. This will allow the concept to grow so that supports and light-weight fuselages etc. could be added without being detrimental to the craft's original performance.

Personally, I would like to consider larger rotor blades utilizing Aerodynamically Active Blade Twist (http://www.unicopter.com/1749.html) ~ at a later date.

Dave

Jens
09-26-2009, 01:48 PM
….. and you made your point more than clear,as did others, with images you think are funny…
If you will not un-confuse yourself – by using a good dictionary – yes, we take the 2. best choice, which is making jokes and big :D about your confusions.

And of course, stay far away from ‘words’ with no clear meaning – like BPH.

StanFoster
09-26-2009, 02:09 PM
I find this thread very interesting. Though its not my type of flying....I am amazed at the accomplishment of creating such a helicopter. Its the challenge that is the catalyst behind the work getting this done.

I would call it taking off and staying in your own backyard flying.... Just hovering with one is an amazing accomplishment.


Stan

Sita
09-26-2009, 07:01 PM
Here is an argument for "Deconstruction" (http://www.unicopter.com/Backpack.html#Weight_Ratio) i.e. increasing the ratio of payload weight to vehicle weight, while improving the reliability and easy of piloting, etc. This is particularly relevant to rotorcraft since they are probably the most inefficient and expensive vehicle there is.



Dave,

you metioned it in the "argument for Deconstruction" but the use of a moulded harness makes a big difference in comfort.
I both used a parachute type harness (only webbing) and a aluminum "corset type harness" and the weight of a BPH (Back-Pack Helicopter for those who could not figured out what the abbrevation is) is much easier to carry with the corset type.
The weight rests on your hips rather than on the shoulder and the body is much more firmly connected to the frame which is an advantage I think.
Weight penalty for such a corset is minimal compared to the gain.

Cita

Rotor Rooter
09-26-2009, 09:52 PM
Cita,

Perhaps this is where I am getting confused with the discussion about the use of the word 'backpack'.

IMO, Baumgartl's Heliofly I (http://www.aviastar.org/helicopters_eng/baumgartl_heliofly-1.php) is definitely a backpack. However a craft such as Frans Schoeffman's (http://www.unicopter.com/Schoffman.jpg) that has some form of ground support may not truly be a backpack. This is because there is probably no time when the pilot's body has to support any of the weight of the actual craft.

A question. You mention "The weight rests on your hips...." Does this mean that your are not planning to implement any type of ground support on your craft?


I would agree that comfort will be come more important as 'backpack' flight times become longer. Just an idea; but what about a type of harness/seat where the bottom portion could be positioned 'up' for extended flying and 'down' for foot takeoffs and landings? Years ago I saw a bucket style of seat with a fairly high back. It was made out of carbon and the person said that it only weighed 1 lb.

This harness/seat could also be the attachment point for battery-packs on an electric 'Backpack'.

Dave

Sita
09-27-2009, 12:38 AM
Dave,

the phrase "back-pack helicopter" can be misleading because in the past some editors of aircraft or popular science magazines found it more spectacular to call any small rotor craft a "back-pack" machine.
The Pentacost Hoppicopter remained to be called a back-pack helicopter even when it had gone through modifications that incorporated a permanent seat and landing gear.

To me,and this is only my opinion,a BPH is a helicopter which has no seat or landing gear other than the pilots legs and can be carried/flown just like the word says,a back-pack.
I feel that when you go through the trouble of adding legs or skids or whatever to assist during take-off/landing you might as well do it properly and this not allways mean extreme weight penaltys,the same goes for the seat.
With only a few extra lbs the Schoeffman can be converted to operate in a much more comfortable position.

The BPH will NEVER replace his big cousin,the UL heli and in that regard one has to deal with the restricted possibility's of the BPH.
The time that a helicopter is doing what it was designed for in the first place,hovering, is minimal compared to it's actual flight time.
So an extreme amount of money is spend on a machine that only uses a fraction of it's main ability during every flight,hovering and take-off/landing.

Schoeffman is in the right direction in that he doesn't need a trailer or a big truck to transport his heli.he simply disassemble his machine and take it via the cheapest way,his minivan, to the point where he likes to use his helicopter.
However,Schoeffmans heli cannot be taken apart rapidly to store it in the trunk of a conventional sedan,for that we really have to go in the direction of the BPH,probably electric.
Fold down the blades and stow it in the trunk.

A fold down seat would be nice Dave but contrary to what paraglider pilots can do,shove the seat under their butt once in the air,this might be rather difficult with a BPH.Letting go of all controls for a few seconds just after take-off is probably not feasable unless a very dependable gyroscope can be used.
Our legs are the heaviest part of our body so I don't know what the shift in position would do to the CG when we shift our legs from vertical to the folded position in front of your body.

Before everybody jumps on my neck again,150 lbs is not the weight of a BPH but a boat anchor !!

Baumgartl's Heliofly is in my opinion a BPH,Schoeffmans machine is an undefined cross between an UL and a BPH.

I would love to see a landing gear that can replace the pilots legs in this terrain.

Cita

Jens
09-27-2009, 02:15 AM
…..I would call it taking off and staying in your own backyard flying.... Just hovering with one is an amazing accomplishment.
Yes. And that could be a new category of rotorcraft, which I would like to call hovercopters.

As in any other game or forum thread, now and then we stop the game, and argue about the rules – right :)
The argument now is about a few words which are too unclear and creates too much confusion in here – which ruins the game.

And actually – I think, it comes down to the definition of only 2 main words:

1. BPH – Back Pack Helicopter
2. Helicopter

More to that later....

Rotor Rooter
09-27-2009, 08:42 AM
Thanks Cita,

Your posting makes it a lot easier to understand what we are discussing.

From your comments, Jen's comments, and my confusion, it appears that we are talking about the lightest VTOL craft possible and then building upon this basic craft. If 'Backpack' implies exactly what it says then I support Jen's call for another name.

Jens, the name 'Hovercopter' may be a good one, however do you think that it might become a little restrictive as the performance capability of light rotorcraft improve?

Putting the name aside for a moment, my personal preference in very, very, very light helicopters is Schoeffman's approach, but in electric. The ability to land without a load on ones back and then leave the craft in an upright position while stretching ones legs is an advantage. And, this advantage might add very little weight, if any.

Dave

Sita
09-27-2009, 09:26 AM
Dave,

I don't see the importance of which name is used to identify a helicopter.
Any aircraft that can hover,fly forward/backwards and sideways,goes up and down in a controled manner and has a whirling wing('s) to do so is a helicopter,NOT a Hovercopter-Gyrocopter-Quadricopter or whatever.

What a waste of energy and time simply because one person likes to introduce the name of hovercopter to replace helicopter for whatever reason.


I'm out of this charade.

Cita.

Rotor Rooter
09-27-2009, 10:15 AM
Cita,

I am sorry that you feel frustrated, but words obviously have meaning.

'Helicopter' has a general meaning.
'Coaxial helicopter' has a more detailed meaning.

It appeared that the earlier confusion was based on the misunderstanding of the type of craft, its means of support during landing, and the safety involved.

http://www.unicopter.com/NoIdea.gif

Dave

Jens
09-27-2009, 10:29 AM
I think:

1. Original definition of helicopter: For about 100 years ago, the common meaning of the word helicopter was a machine that could hover, maybe just 1ft above ground, standing still or move slowly around and you had a helicopter.
2. Todays definition of helicopter: A machine which has hover capabilities and is capable of flying high and fast – safely.

There is a BIG difference in building the 1. and the 2.

Depending on your level of interest, knowledge and involment, you need different words for cars as well as for helicopters.
Sure, for those who have no big interest in cars or helicopters it works fine with, 'A car is a car and a helicopter is a helicopter' .

I forgot:
For def. 1. I suggest hovercopter. If enough agree it will end up in the dictionaries.

Jens
09-27-2009, 11:18 AM
...a BPH is a helicopter which has no seat or landing gear other than the pilots legs and can be carried/flown just like the word says,a back-pack.
Excellent, that is a clear definition for BPH – Back Pack Helicopter.
But only when we also have a clear meaning of helicopter: A machine which has hover capabilities and is capable of flying high and fast – safely.

If you have the machine on your back, and it can not fly high and fast - safely, I would suggest to call it a Back Pack Hovercopter.

Again, 2 very different machines to build and very different in use.

This way, a lot of confusion could be avoided - I am sure.

tyc
09-28-2009, 07:01 AM
[B]
... But only when we also have a clear meaning of helicopter: A machine which has hover capabilities and is capable of flying high and fast – safely.
If you have the machine on your back, and it can not fly high and fast - safely, I would suggest to call it a Back Pack Hovercopter.


"... fly high and fast - ..." relative to what?

tyc

Jens
09-28-2009, 07:31 AM
tyc,

I think the meaning is already pretty well understood.

From a hovercopter point of view:
It is high and fast when you are likely to kill yourself in case of a major mechanical malfunction.

What do helicopter buyer’s and other people expect from a helicopter? Much more – I am sure.
Precise figures are not needed I think.

A hovercopter is very low and slow compared to a helicopter.

Monte55
09-28-2009, 09:25 AM
I finally got to the point after securing and safety pinning most of the bolts
and fixtures so that I could safely run the engine, drive shaft and rotor head
components and see how they worked. No rotors at this time. Here is a Youtube
video

Here is the link:
http://www.youtube.com/watch?v=Do9cElBSWjY

Nick

PS this is starting to get exciting...and scary....

Rotor Rooter
09-28-2009, 10:01 AM
Nick,

Looking good. http://www.unicopter.com/ThumbUp.gif


PS. I like Nick"s choice of the work 'Microlite', but have it apply to craft that have some type of supporting and are significantly lower in weight then the Ultralight weight limit of 254 lb.

Jens
09-28-2009, 11:00 AM
… this is starting to get exciting...and scary....
I totally agree with you. Be carefull.
Hope you have planed a to add few safety things before start of real test with rotors on.

I just love the attitude you have to this project.
That way you can only win – you have won :peace:

Thank you very much for sharing it with us.

Jens
09-29-2009, 07:34 AM
... significantly lower in weight then the Ultralight weight limit of 254 lb.
Only the very best can make a 1 person helicopter below 254lb.

For a 1 person hovercopter you need a few less hp and can risk using a higher tuned engine at maybe 10.000rpm.
Nick has to be as good as the best heli boys to end on 200lb :plane:

Monte55
10-02-2009, 11:59 AM
I did a search and couldn't come up with the info I need.
I'm ready to balance my short (48" each x 4 rotors) I have made. What is the best way to balance them? I can hang two of the matching blades and add weight to the light blade,........but where should the weight go on the blade?
I'm sure the balance weight will have a different effect depending on where it is placed on the blade.....root, middle, or tip. the added weight will be less than one ounce for a five pound blade. If I attatched two matching blades to a "teeder totter" setup....even when I find the weight to make them weigh the same, where I put the weight on the lighter blade to have it balance as compared to the other on the teeder will make a difference. I hope this makes sense. Now, they can not be balanced on the rotor head as it is rigid and does not pivot on a bearing. It has to be done on the bench. All input welcome.
Nick..........thanks guys

PS I saw a video of a guy balancing a wooden prop and the weight was placed at the hub. I don't think that will work with my situation. Thoughts?

Jens
10-04-2009, 04:46 AM
Hi Monte,

I have only experience from 2 home build projects with props.
When I did my first paramotor, which was just as homebuilt as your project, I was also very concerned about the prop. Mounting, balancing etc..
Later I damaged the prop 2 times and repaired it and balanced it – no big deal.
The point here is; putting 15 hp in a 49” prop, nothing is really very critical. And you have some similar situation as I see it.
I just did a static balancing. Turned the the prop and looked where it stoped.
On the preliminary balancing I used tape and later I used paint on the outer half of the prop. Both worked fine for long time.

I think - don’t worry too much about balancing.

quadrirotor
10-08-2009, 07:17 AM
It seems to me that you'd better have, to save your back, some kind of crashability!
May be this one is better! built with a solid cage...

http://www.youtube.com/watch?v=OT9UZQcaNag&feature=player_embedded

Rotor Rooter
10-08-2009, 08:41 AM
It seems to me that you'd better have, to save your back, some kind of crashability!
May be this one is better! built with a solid cage...

IMHO, the better solution is to go in the opposite direction.

Significantly lighten the load (Empty Weight) of the system by using fewer (and lighter) components,
then;
~ Improve the flying characteristics of the craft.
~ Increase the reliability of select components.
~ Use redundancy where necessary.

Everything directed at reducing the chance that the pilot or the craft can cause a crash.

Dave

quadrirotor
10-08-2009, 09:26 AM
Did you fly anything, Dave?
Did you ever try to take off, and land, only with a motorized paraglider, with 50 lbs on your back? :?

Rotor Rooter
10-08-2009, 11:46 AM
Did you fly anything, Dave?
Did you ever try to take off, and land, only with a motorized paraglider, with 50 lbs on your back? :? I owned an airplane with low wings. Its problem was just the opposite of what you are contemplating. When the tanks were near empty, it was difficult to get the craft down on the ground.

I have only 1 hour of training with a paraglider, and the prop+motor was not on during the training.

The backpack helicopter with tripod support is a TOTALLY different situation from the above. It can be placed vertically and slowly on the ground, under total pilot control due to it's fast response. This is apparent when looking at the Schoeffman films (http://www.unicopter.com/1764.html#Schoeffman).

The PRIMARY safety concerns left to be addressed are;
~ Reducing the number of parts and the weight.
~ Making the craft aerodynamically safe to fly in lateral flight.
~ Making sure that these few parts have very high safety factors.
~ That maintenance is very infrequent and its necessity is observable.
~ Making sure that there is, at the least, a short period of power at the time of landing.

IF the craft was able to obtain a safety level that exceeded all other rotorcraft and private fixed wing craft, and the IF the pilot received training, then the only factor left is that of the pilot and his affinity with Darwin.

Dave

Sita
10-08-2009, 01:56 PM
Did you fly anything, Dave?

So,those who have ever piloted an aircraft/rotorcraft are the only ones who can come up with an idea,a concept?

Did you ever try to take off, and land, only with a motorized paraglider, with 50 lbs on your back? :?

Why keep people comparing a BPH or Schoeffman type heli with a paraglider?

The higher the weight,the more gravity will put it's mark on an emergency landing.

Terry
10-08-2009, 11:20 PM
Maybe someone's posted this already:

http://www.flixxy.com/personal-helicopter.htm

Sita
10-09-2009, 02:03 AM
Maybe someone's posted this already:

http://www.flixxy.com/personal-helicopter.htm


Terry,
this has been posted a zillion times in this thread,
but thanks anyhow !

Cita

Jens
10-09-2009, 08:25 AM
Did you fly anything, Dave?
Did you ever try to take off, and land, only with a motorized paraglider, with 50 lbs on your back? :?
Dave will not carry anything on his back. And not use it as a helicopter.
That is what he are saying most of the times - I think.
Others will and can - they say - carry ‘2 paramotors’ on their back!!
They call them all BPHs. So it is very hard or impossible to know which type they mean.

1. The through BPH is perfect for fantasy, concept dreams and lots of arguments, and has a proven record of not working.
2. The traditional heli frame, with fixed rotor, is very limited in use – practically almost only hovering on the spot. Most heli people say it is even too dangerous for that. They might be right.
3. The Schoefman type has a proven record of working.

Rotor Rooter
10-09-2009, 10:35 AM
Stability and the Ground;

If a person is standing with his hands on a railing and his body's center of gravity moves forward for some reason, he has two ways of positioning his feet back under his center of gravity.

One way is to take a step forward.
The second way is to push back on the railing.

BOTH of these two INSTINCTIVE methods are also available to Schoeffman.


Dave

Jens
10-10-2009, 12:39 AM
The heli frame type can be improved considerably - I think.
COGs just have to be in-line.
With 2 engines, 1 on each side of body, this is possible. Complex compared to Schoefman type, yes.

With the heli frame type you have the COG of machine much lower as for the Schoefman type, but with COGs in-line, you can still use your legs when starting and landing.
You can say, body and machine have each its own set of start and landing gear, and this is the only way to go with fixed rotors - if you want to fly it safely as a hovercopter.

Zigge
10-11-2009, 02:31 PM
Dave will not carry anything on his back. And not use it as a helicopter.
That is what he are saying most of the times - I think.
Others will and can - they say - carry ‘2 paramotors’ on their back!!
They call them all BPHs. So it is very hard or impossible to know which type they mean.

1. The through BPH is perfect for fantasy, concept dreams and lots of arguments, and has a proven record of not working.
2. The traditional heli frame, with fixed rotor, is very limited in use – practically almost only hovering on the spot. Most heli people say it is even too dangerous for that. They might be right.
3. The Schoefman type has a proven record of working.

But the Nolan coaxial works fine if you aske me...
and it has fixed rotor pitch (if thats what you mean with fixed rotor)
http://www.youtube.com/watch?v=0QHfBucsL0Q

Rotor Rooter
10-11-2009, 04:33 PM
Zigge,

Every single helicopter design has its shortcomings.

In the middle of the last century a lot of work was being done to develop a viable VTOL craft. It eventually became apparent that a rotorcraft, which was reliable & economical, was an oxymoron. Creative new concepts became fewer and fewer.

The two latest ideas, that of the tilt-rotor and the coaxial-ABC are regurgitations of 40 year old ideas. Bell is trying to use the wing and then have rotors that act as propellers (& visa-versa). Sikorsky is trying to use the propeller and then have the rotors act as a wing (& visa-versa).

Could it be that rotating blades were never intended to travel radially within their environment. It seems that nature's evolution knew it all along.

IMHO, Bell has got to find someway to vary the disk size v.s.the disk loading, to be effective in both realms of flight. Sikorsky has to find someway to have the rotor-blades work efficiently in reverse air-flow to be effective in both realms of flight.


Perhaps, the previous developments of composites etc. combined with the future developments of electric propulsion will lead to a reliably and economical VTOL craft that flies axially quite well.

'A helicopter in every garage'
Could Sikorsky's dream be Schoeffman's realization?


Dave

Sita
10-12-2009, 02:01 AM
Zigge,

..........The two latest ideas, that of the tilt-rotor and the coaxial-ABC are regurgitations of 40 year old ideas.........


Dave

Dave,

I believe that the tilt-rotor concept was proposed just prior, or during WW II by an English gentleman,so it's closer to being a 60 year old idea,nothing new under the sun.
It just proves that old idea's can have merrit with new technology,not available when the idea was born.

Cita

tyc
10-12-2009, 06:17 AM
... It just proves that old idea's can have merrit with new technology,not available when the idea was born.
Cita


I'm sure Leonardo DaVinci would agree with you. :-)

tyc

Jens
10-12-2009, 08:42 AM
But the Nolan coaxial works fine if you aske me...
and it has fixed rotor pitch (if thats what you mean with fixed rotor)
http://www.youtube.com/watch?v=0QHfBucsL0Q
I agree, the meaning of 'fixed rotor' is not 100% clear.
I meant fixed pitch, no collective pitch and rigid blades - as fixed as it can get :)
Fully fixed rotor - might have been a better wording.

Look like Nolan have substituted the collective pitch with double power = 2 x Rotax 582 = 130hp.
Few, or only Nolan, have choosen this solution for a helicopter.
Few will consider over or double power a solution for a homebuilt hovercopter.
(But they have to, if they choose fully fixed rotor and the heli frame type, and still want more safety.)

Right, Nolan have shown that a fully fixed rotor can be safe for a hovercopter!
But Nolan is NOT a safe helicopter, as you have no autorotation cababillity.

As I understand it.

Zigge
10-12-2009, 11:25 AM
I agree, the meaning of 'fixed rotor' is not 100% clear.
I meant fixed pitch, no collective pitch and rigid blades - as fixed as it can get :)
Fully fixed rotor - might have been a better wording.

Look like Nolan have substituted the collective pitch with double power = 2 x Rotax 582 = 130hp.
Few, or only Nolan, have choosen this solution for a helicopter.
Few will consider over or double power a solution for a homebuilt hovercopter.
(But they have to, if they choose fully fixed rotor and the heli frame type, and still want more safety.)

Right, Nolan have shown that a fully fixed rotor can be safe for a hovercopter!
But Nolan is NOT a safe helicopter, as you have no autorotation cababillity.

As I understand it.

The thing about auto rotation is a very good thing if it is ment that it will save you if you have a engine problem, but if you as the Nolan have two engines you can still fly/land if you have ONE engine problem so I thing it would be safe to fly the Nolan if even if it can not auto rotate, it would be even safer than auto rotation since the Nolan would probably fly with only one engine (perhaps just)

brett s
10-12-2009, 11:29 AM
Both engines can quit - it's happened before on certified ships, much less 2 stroke powered experimental helicopters. If you're at anything other than a hover in ground effect you probably die...

Bad design for flying higher than you care to fall.

Zigge
10-12-2009, 11:50 AM
Naturally both engines can quit, if you have 10 engines they all can die to, but if a copter like this is probably not used for high and long flights and if you ask me the risk of two engins braking down with in a few minutes of time is not something that happens every day, but I get your point.

One way is to have separate fuelsystems and and and so on, but to be honest I think that most of us DIY would settle with the safety of two engines and fly around the house just to feed our ego...
or is it just me?

and all the talk about speed and performance and all the other theoretical stuff that is held against these small and cheep machines is for the airforce or airlines to deal with, me and I think many others would settle with a Nolan or a GEN-4
(sorry for my bad spelling my exuse is that Im from Sweden)

brett s
10-12-2009, 12:05 PM
I'll take collective pitch over a second engine any day.

Jens
10-12-2009, 12:15 PM
Zigge,

The Nolan is not small.
The GEN-4 is not simpel nor cheap.

Both are quistionable used as helicopters.
But we can learn from both.

Sita
10-13-2009, 01:07 AM
I'll take collective pitch over a second engine any day.

Brett,

you're probably right when you're talking about a UL or small homebuilt (Mosquito-Rotorway etc...) helicopter.
They have enough kinetic energy stored in the blades to use the collective in an emergency but I doubt that the very light blades of a BPH can handle a sudden pitch change and keep proper rotor RPM.

Just my two cents.

Cita

Rotor Rooter
10-13-2009, 09:56 AM
Brett,

you're probably right when you're talking about a UL or small homebuilt (Mosquito-Rotorway etc...) helicopter.
They have enough kinetic energy stored in the blades to use the collective in an emergency but I doubt that the very light blades of a BPH can handle a sudden pitch change and keep proper rotor RPM.

Just my two cents.

Cita

A rotor governor (http://www.unicopter.com/Governor.html) will solve the above concern, by automatically lowering the pitch.

Then a short-term source of energy is needed that can be applied to the rotors during an autorotative touch-down?


It appears that the Flettner FL-282 was the first to use a rotor governor.

Rotor Rooter
10-13-2009, 10:08 AM
Alternative backpack (http://www.youtube.com/watch?v=0snTqLQLpBA).

Rotor Rooter
10-13-2009, 10:12 AM
Alternative. Depart the backpack - preferably over water.

http://www.unicopter.com/DropInSometime.gif

brett s
10-13-2009, 10:13 AM
Just because you lose power doesn't mean you always lower collective pitch - doing so at the wrong time guarantees a crash.

There's a reason you don't see such devices on helicopters other than maybe one or two 1940's designs that rapidly disappeared.

Before you start designing a helicopter, why not learn to fly one first? You'll clear up some of those misconceptions...

Rotor Rooter
10-13-2009, 11:51 AM
Brett.

You are fundamentally correct, as we have discussed before. However, the above response is directed specifically at the 'MicroLite'/'backpack' concept.

It appears that current small rotorcraft with; no collective, 'absolutly' rigid rotors, 'relativly high' disk loading, and low rotor inertia, must fly within a few feet of the ground, for safety reasons. Also, it can be assumed that these craft would be unsafe at speeds above ?? mph, no mater how close they are to the ground.

In addition, perhaps the collective pitch on these craft is fixed at optimal lift and their rotors could not even sustain autorotation. Does anyone know? [I think that Pegg did a NACA report on this subject many years ago]


My chalange is to provide this type of craft with the ability to fly safely outside of ground effect and with a respectfull forward velocity.
The primary means of acheiving this is by giving the craft an extremely high assurance level that power can be delivered to the rotors for a fraction of a minute at touch-down.


It seems that dropping the collective on a low inertia rotor when at altitude, is more important than raising the collective to squeeze a little extra lift of a low inertia rotor when touching down.

This is the current thinking for a basic microlight;
~ It has a 2-position collective that will automatically drop upon loss of power, due to a torque-pitch coupling .
~ At altitude the pilot will autoratate the craft to the selected site. Just before landing he will flip a swith that will provide the emergency power for lift to decrease his descent rate, flare and touchdown.
~ When setting up for a conventional landing the pilot will also flip the switch. This will allow the emergancy power to automatically come in to play and a warning alarm to sound, should, the primary battery fail.


[URL="http://www.unicopter.com/ElectrotorMicrolite.html"]This is the current state of this Electrotor-MicroLite project.[absolutelyrelatively/URL] So far , so gochallengerespectfulachievingod.


Dave

Jens
10-13-2009, 01:19 PM
….Before you start designing a helicopter, why not learn to fly one first? You'll clear up some of those misconceptions...
That’s right - that would help. Although he could do both - I think.
But we need to balance theory with practical doing, to become a better anything!

To prove my point – look at those able people, who have come up with new things, and see how much doing these have been capable of :yo:
Rather amazing in most cases.

Jens
10-14-2009, 09:49 AM
Good to know, that a machine with a tilt able fully fixed rotor is controllable if you have enough power.
Unfortunately I am quite sure, with loss of power from one of the 2 engines, the good control is gone, and then the Nolan is too unsafe even from low altitude with a little speed :ohwell:
It will tumble easily.

Modify the Nolan to dual start & landing gear - per sketch below.
One gear for the machine itself, and one 'gear' (your 2 legs) for the body.

Compared to the Schoefman type,

Advantages:
With 1 engine out, the second engine can easily lift the machine itself.
COG can be very low – means less liable to tumble.
You can use heavier engines if you like.
Add damping in the landing gear.
It look more like a helicopter – although it is a hovercopter and should only be used as such.

Disadvantages:
More complicated.
Heavier.
More hp's, fuel and noise.

But maybe this could be as good a solution as the Schoefman type?

Zigge
10-19-2009, 08:19 AM
Jens
I think your drawing is very interesting and looks like wort a try, but why make things more difficult by using your legs as landing gear?
a machine of that weight will not be very partable anyway...

and why would the COG be of any importance? a regular heli all have their engines mounted high, just the cabin below the engine and gearbox, so they should have a very high COG.
or is it just for the person that lift the machine you are looking for a low COG so that it wont fall over when moved on the ground?

Just wondering, because I find your drawing reminding of my design that Im woking on (dont we all have a dream of building our own heli:humble:)

Jens
10-20-2009, 08:06 AM
Hi Zigge,

Helicopters have precise and responsive controls in all directions, by means of cyclic and collective pitch.
Helicopters need a trained pilot.
Helicopters are, in the main; build from reliable aircraft parts and materials.

So a helicopter always have practical zero ground speed at touch down = it don’t tumble – too often!
If you mean helicopter – go the proven way – don’t use double landing gear, fixed rotor head etc..

You see what I mean?

Rotor Rooter
10-20-2009, 08:29 AM
You mean something simple like this? :)

http://www.unicopter.com/0250.gif

tyc
10-20-2009, 11:23 AM
Now that you have the drawing(s), take it to the next step . . . As small as the unit is proposed to be in real life, contstruct a cardboard or balsa model of it; say one quarter (1/4 or 25%) scale. Do that and make note of the changes which will be needed prior to building a prototype. :-)

tyc

Rotor Rooter
10-20-2009, 02:51 PM
tyc,

If your talking about the above drawing where the guy is just about sitting on the grass, it already is small. :)

It is just an alternative to tripod supports, and the two of them could be interchangeable at the gimbal.

Dave

Zigge
10-21-2009, 05:42 AM
Man have you hacked my computer???
Ha Ha Ha It looks almost like my design!
The only difference is that my chassi is going for powdercoting next week:)
and the gearbox is a full cad design just waiting to be made...
it will have 2x40+ Hp engines and according to my calculations I will still have 35kg of lift left with a pilot of 90kg, if one engine fails, so it will hopfully be able to make a safe landing on one engine...

Jens
10-21-2009, 07:37 AM
….. It looks almost like my (Dave’s) design!
…..it will have 2x40+ Hp engines and according to my calculations I will still have 35kg of lift left with a pilot of 90kg, if one engine fails, so it will hopefully be able to make a safe landing on one engine...
The last part sounds very good. About what is needed for lifting a 90kg body with 2 props and have some extra power for control - I think.

The first line is very BAD news. More unsafe than the heli frame type!
Body fixed to the frame, COG that high and right on top of your head :eek:

Unless you design and build it with no less than usual standards for helicopters, you will very likely hurt or ruin your body, if not die, when you go much higher than 1 ft. – I am sure!

Don’t forget, that also a machine even just used for hovering, can very fast turn into a painfully and bloody affair – especially if the basic design is unsafe and build from unreliable parts.

Do you think of using it only for hovering or as a usual helicopter?

Zigge
10-21-2009, 08:31 AM
The parts I will use are made by myself, using cad calculations with at least a safetyfactor of 2, and When I have calculated it I will give all the data to an other company to get a objective oppinion and a second calculation just to eliminate errors that my and my partner may have done. (We can all make misstakes)
rotorhubs will probably simailar to autogyro, but that is still to come...

The weight is around 150+kg but I have not focused on weight at this stage.
The frame is built like the cage in a racecar to support the weight of the engines.
The gearbox is to be made from "aircraft aluminium" at a company that makes parts to aircrafts and also have made gearboxes to turbine boats.
Engines used just as reference is Rotax 447, but the best power/weight ratio is the Wankel engine that weighs 17kg and gives 50Hp!!

In the picture the landing gear is missing but the bow shaped composit springs are there (springs from Skyrunner jumpstilts) and the fastening point betwen gearbox and chassi is not correct and the main mast and hubs are just sketches
http://img137.imageshack.us/img137/9863/assemchassvxl.jpg

Jens
10-21-2009, 09:21 AM
Very nice Zigge. Thank you for posting it.
I understand that you are going for actually building and using what you design :peace:

Your machine is not comparable to the Schoefman type, although it look like a Schoefman – but it is NOT – as I see it.
Your machine should be compared to a usual helicopter – like the Mosquito.

I am more interested in a machine only for hovering, where controls, engine, parts and standards are more for the hobby home designer and builder.
All my ideas are aimed at, what I call, a hovercopter, so I will not comment too much on your helicopter.

Great to follow you work – I look forward to read and see more to it.
_______________________________

Agree, 2 Wankel engines looks good, if we have to place them high. But even that weight might be too much up there – I think.

Zigge
10-21-2009, 09:39 AM
Thanks Jens
I try not just to talk...

Well it will be quite simillar to the Schoefman type, weightshifting for control etc..
and the weight on top will only be a problem when being on the ground and landing, and landing has nothing to do with flying:peace:

today I will finish the chassi, but the gearbox will wait a bit since it has been changed a few times, and who knows perhaps it happens again :)

Perhaps I will start a my own thread when I have more pictures

Constructive critisism is welcome. (not about my spelling:bored:)

Jens
10-21-2009, 10:13 AM
…..Well it will be quite similar to the Schoefman type, weight shifting for control etc..
and the weight on top will only be a problem when being on the ground and landing……
“Quite similar to Schoefman..” I see that quite differently.

1. Schoefmans first decision was, “I just want to hover”.
2. Now he could risk to use a 125cc 2T engine putting out continiously about 30hp, using a gocart chain drive etc. – all VERY light weight. Lasting for a short time of course.
3. Now, with the use of those parts, he will now and then fall down without any lift, and he has to handle that.
4. He solved 3. with double landing gear – legs for body, which is more than half load, and a tri pod for the machine itself, which he now could support because his body is already on the ground.

For your machine Zigge, controls and reliability has to be as good, as for a usual helicopter.
You instantly have an accident with engine out or something. THIS IS A BIG DIFFERENCE.
Therefore your machine – as it is now - is more comparable to a Mosquito than a Schoefman.

My thoughts.

Yes, only landings are dangerous...!

Rotor Rooter
10-21-2009, 11:59 AM
We have been unable to find an existing propeller or rotor blade that will do for the Electrotor ~ MicroLite (http://www.unicopter.com/ElectrotorMicrolite.html), so we will have to create our own.

If it is of any interest or value, here is the current blade profile that we intend to use. MAKE: Electrotor-MicroLite ~ Rotor - Blade - Initial - VR-7 (w/ 18% thickness) to VR-8 Tapered - CW & CCW (http://www.unicopter.com/1792.html)

The intention is to wrap carbon cloth around a foam core.

The first company was not cutting the foam cores well enough with a hot-wire so we are getting a quote from another company for CNC cutting. In addition we have increased the root thickness from VR7 w/ 7" chord to VR7 with 7" chord & 18% thickness, to increase the rigidity of the blade.

Suggestions or concerns are appreciated.

Dave

Jens
10-22-2009, 08:36 AM
Zigge,
I think we have had some of the same thoughts about the Schoefman type and 2 engines…

Advantages of placing engine(s) at top are significant: Very simple power drive and possibility for a simple weight shift control. Unbeatable in simplicity.
Disadvantages are also significant: COG very high and a heavy lump of metal just over your head!

2 engines also have significant advantages and disadvantages.
If weight can be kept below 50kg/100lb I like the safety 2 engines gives – but it complicates things.

I have been thinking of using 2 Swedish Radne engines:

http://www.radne.se/Store/Product/ProductDetails.aspx?PartNo=3201-4

It has 15hp, but can be tuned to about 18-20hp. Unfortunately are 36-40hp probably still too little for a body weight of 90kg/200lb.

Zigge, how do you plan to make the counter rotating gear?

Zigge
10-22-2009, 10:43 AM
http://img148.imageshack.us/img148/1893/dsc01153f.jpg
http://img148.imageshack.us/img148/2825/dsc01154e.jpg
The seat is not fitted, it will come higher...
Jens

My project started out just like yours but grew with time, one reason was that I wanted to have more power and then the weight increased and then the safety needed to be higher and stronger and so on...
The main safety of my craft is that it must be able to fly with one engine!

The coaxial gear is the key to it all, I am not using the classical gear between rotors, I have designed a gearbox that is below the rotors and engines on the sides the box has two in going drive shafts.
The gearbox is ready to manufacture, but I need to calculate the forces in the two masts first so I know that everything is ok, as a reference I will use the strength of a Mosquito mast

I would like to post pictures of the gearbox but I am looking in to making some Patents on some parts if possible.

Jens
10-23-2009, 08:37 AM
Wow - you have started building it - great!

And I understand, that you are aware that it IS a real helicopter.
For me, all helicopters (and gyrocopters) are too scaring.
Hovercopters (and gyrogliders) are okay :-)
But helicopters are not dangerous to design and build – only to use - so it is very motivating to see your work -and a great joy.

I think it will fly very well and land very well – as long there are no mechanical malfunktions.
Probably ok with that much weight that high when you have a strong cage underneath and a wide landinggear.
But you should land your body on you legs no matter what hight you come from. It don't handle every thing, but can be a big help if control go a little wrong.
I know you don’t agree too much – but that’s my thoughts.

Your country Sweden is neighbour to my home country Denmark, as well as my job country Norway, so the day you start testing, I come by :) … ahh… I mean if I get invited.

Zigge
10-23-2009, 08:45 AM
It seems as if you and I dont agree on if its a Schoefman type or a "real" helicopter, but since it will have fixed pitch and weight shiftnig for control I say its a "Schoefman type", I tried yesterday to find its COG and it tilted forward, but the ruder at the back is still to be welded on...
It must be it "total" balance to get the best from the design.

You are most welcome when it is time to test:drum:
But I will take some time, it takes a lot of time tom bulid, the chassi has taken some 30 hours and the design with the compost springs are not ok so I must change that, it is too soft now.

All_In
10-23-2009, 08:47 AM
Pier, wow that was fast! I love builders that just do it and this site.

It looks like a copy of Santa Sleigh? :boink:

Way to go Pier!

Jens
10-23-2009, 09:31 AM
Zigge, I will say yours is a mix of a Schoefman and a Nolan.
But yours and the Nolan are helicopters.

Schoefmans machine is for hovering around only. Only a big fool would use it otherwise.

But let us agree that we disagree ;-)

Jens
10-25-2009, 11:37 AM
I know rescue parachute have been discused before - BUT:

For all coaxial heli's, it should be possible to make a simple and effective rotor brake - especially for low inertia rotors or props.
When the rotors or props are stoped, you should be able to get free and use a simple 10lb/4kg rescue paracute - right?

Have anyone heard of or seen anything like that?
Do you have some idears about this?

brett s
10-25-2009, 11:59 AM
At typical altitudes most recreational rotary wing pilots fly it's not very likely.

If your design isn't capable of autorotation you've got a pretty large part of the flight envelope where you're toast in the event of a power failure even with a chute.

Better off building a design that can successfully autorotate & respecting the H/V curve while flying it IMO. Or don't ever fly out of ground effect or more than walking speed...

Rotor Rooter
10-25-2009, 12:32 PM
Brett's limitations in regards to safety are very valid.

One potential solution is to add; a ballistic parachute, a second engine, a strong and energy absorbing fuselage and skids, and wheels etc. etc. The weight of all this will put an additional loading on the other components, which will then have to be made stronger and heavier. It is a recursive spiral upward in weight, complexity and price.

An alternative solution is to recursively reduce the craft.
Think http://www.unicopter.com/Lightning.gif No gearbox, reduced weight, assured thrust at during touchdown, etc. etc.

It is coming!
The question is, where will the primary interest in electric recreational rotorcraft come from? A rotary wing forum or a R/C forum????


Dave

Jens
10-25-2009, 01:09 PM
I don't like to go high in any rotor craft machine!
A hovercopter and a gyroglider is enough for me ;-)

Build something like the GEN H-4 with 2 wankel engines (2x50hp) and mount it with low inertia props.
Now you have a 2. engine - should be powerfull enough to get you down alive.
And if you could make a rotor brake for the props, you also have the rescue paraschute from above 2-300ft. - right?
In this case, this type of helicopter have a comparable safety to other helis - or?

No one heard about or seen a rotor brake and rescue paracute for coaxial helicopters?

Rotor Rooter
10-25-2009, 03:21 PM
Jens,

Brett has mentioned the 'Above Ground Level' limitations of a parachute. Even a ballistic parachute will have an AGL limitation.

IMHO, there are many ways of storing short-term power, for use during an emergency flare.
In addition, reducing the weight of the craft reduces the disk loading on the small rotors.

Dave

Jens
10-25-2009, 10:40 PM
I am interesed in the quistion:

Have anyone heard about or seen a rotor brake and rescue paracute for coaxial helicopters?

earthbnd misfit
10-26-2009, 01:26 AM
If you had a rotor brake powerful enough to stop the rotors before you hit the ground, then the torque reaction will make you spin like a top.
The simplist would be to mount the chute on the top of the rotors like the camera on an Apachy heli, and a swivel joint. Operate it with a remote system and spring loaded pilot chute.

tyc
10-26-2009, 07:25 AM
... Have anyone heard about or seen a rotor brake and rescue paracute for coaxial helicopters?


Have you considered putting the rotor blades under the pilot?

tyc

Rotor Rooter
10-26-2009, 07:27 AM
http://www.unicopter.com/lightbulb%20idea.gif
Where the lights are never turned off ~ because the light never really came on.


For emergency power-off landings;

The pilot's harness is attached to the microlight helicopter by a bungee cord. At the prescribed elevation above the ground, the pilot jumps. At the botom of the jump, the pilot releases the bungee cord and then runs like hell before the helicopter comes down on top of him.


http://www.unicopter.com/Chairshot.gif OK It was just an idea. :ohwell:

Jens
10-26-2009, 11:13 AM
If you had a rotor brake powerful enough to stop the rotors before you hit the ground, then the torque reaction will make you spin like a top....
Yes, for one bladed heli. Here you do the braking between the blades and the heli frame.
No, for a coaxial heli. Here you do the braking between the blades. As they run opposite to each other they could stop each other without any torque to the frame.

And I can’t believe, that I am the first who have thought about that.
Somebody has probably not just thought about it, but already tried something somewhere - I guess.
And maybe they have dropped it because they tried it on too high inertia rotor blades?

Especially when you use low inertia props, you should have a fair change to stop them. Within a few seconds they loose 90% of their energi when power goes off, and they don't speed up very much due to some airspeed - I think.
A rescue paracute is reliable, easy to use, cheap and light weight.

Solve this brake problem and the GEN heli type, with 2 or more engines, would have a safety comparable to other helicopters – agree?

Jens
10-26-2009, 11:29 AM
Have you considered putting the rotor blades under the pilot?
Yes, I have - for hovering around.
The rescue paracute are for those who insist on using these small contraptions as helicopters :eek:

brett s
10-26-2009, 11:53 AM
Solve this brake problem and the GEN heli type, with 2 or more engines, would have a safety comparable to other helicopters – agree?
Nope - as Dave & I both already pointed out.

You need a pretty fair amount of altitude to get your blades stopped & chute deployed - and also keep in mind as soon as the blades start slowing down you're totally out of control, there's no guarantee you'll stay upright or even remotely stable.

If you're talking about a manually deployed chute or having to exit the aircraft first it's much higher - getting out of a falling/tumbling aircraft isn't easy. I know Boeing CH-47 test pilots wore chutes, the times where they actually tried to use them the success rate was below 50%.

It's not the same thing as the H/V curve on a traditional helicopter where you can avoid it entirely with proper flight technique, below a certain altitude a chute is just ballast.

Jens
10-26-2009, 01:58 PM
Brett, I agree in most of it.
Right, you probably will tumble. The same problem has most other aircrafts as well, I think.

But I do think it all can go pretty fast; to stop the props, to get out of a GEN 4 type and to deploy a rescue parachute.
Maybe the best would be to throw the cute as soon as the props stop, and then get free of the GEN 4 heli type - or take it with you down.

In PPG the usual way is to take the machine with you down in the rescue cute.
The extra weight is about 70lb. For a GEN type heli the weight would be about the double. Might be the way to do it.

To be a success, there probably has to be low inertia props on top.
Really, I don't know how safe it would be. But I know I am neither the user - nor the test jumper.

The dual engine gives some safety.
From 3-500 ft you also get some safety from the parachute.

Parachutes for Boeing CH-47 have been used, for other helis too?

brett s
10-26-2009, 03:21 PM
The Boeing guys only wore chutes on experimental or new production aircraft initial flight testing.

They were only used in the event of flight control or structural failure, if you still have control of the aircraft you're better off flying it to the ground.

karlbamforth
10-26-2009, 05:27 PM
If you were to insist on a parachute then it would probably be best to do it the way the Germans did on their submarine gyro glider.

A lever jettisons the rotorhead, as the fuselage falls away the parachute is deployed by the departing head and blades. This was all meant to be done at relatively low altitude albeit over water. I don't know if it was ever used or was just there to con the pilots into thinking it was safe.

Trying to stop the blades and then deploy a chute would probably take something like 4-5000 ft. Not many helis fly that high.

tyc
10-27-2009, 08:49 AM
... below a certain altitude a chute is just ballast.


In my discussions with a ballistic chute manufacturer, I believe the "certain altitude" in question is about 100 meters/300 feet, minimum.

tyc

brett s
10-27-2009, 09:57 AM
Sounds about right to me - and the other chute options discussed would need far more than that.

Jens
10-27-2009, 10:07 AM
:focus: soon.

But I just came across this hard to believe stuff:

Vincent Seremet is still active - although not with BPH's.
A few years ago he flew a rocket powered wing at 370 km/h or 230mph.
Now he plan to go 500 km/h or 310mph - before he turns 80!

Jens
10-27-2009, 10:17 AM
The idear is not new... :D

Stoney
10-27-2009, 11:24 AM
The real life Wylie Coyote rocket powered skates.

http://www.rocketbelts.americanrocketman.com/michaelson.html

http://www.rocketbelts.americanrocketman.com/people/CAPT_ROLLER_BALL_PROMO.gif

Jens
10-27-2009, 02:14 PM
I am derailing my on subject - rotor brake - but I will make an exception here, because I think Vincent Seremet is an icon for the BHP people.

I just googled his name and more recent artickels come up.
Like this one http://www.e-pages.dk/bgmonline_ve/164/
I copied the pictures.

The newspaper say he will do it within a few months near Munchen in Germany.
From a Hercules in 6 km hight he will jump and dive with the rocket wing and try to reach 500km/h and land in a parachute.

Al_Hammer
10-29-2009, 10:22 AM
That is a very inspiring old guy!

Legs for landing gear: Maybe with these legs (http://www.youtube.com/watch?v=67CUudkjEG4&feature=player_embedded) it would be a good idea.

Sita
11-03-2009, 05:58 AM
That is a very inspiring old guy!

Legs for landing gear: Maybe with these legs (http://www.youtube.com/watch?v=67CUudkjEG4&feature=player_embedded) it would be a good idea.

Very inspiring....but not even close to what a human can do.
Our leggs are not as bad a landing gear most think.

Thanks anyway for the interesting link.

Cita

Jens
11-03-2009, 08:12 AM
I mean,
Legs for landing of the body only - with zero load on the body :peace:
And a seperate landing gear for the machine.

I think Cita mean,
Legs for landing gear when body are loaded with about 100lb :eek:

Right Cita?

Rotor Rooter
11-03-2009, 10:07 AM
Legs v.s. Skids

If a gimbaled microlight rotorcraft with skids is about to touchdown and it has excessive forward velocity the pilot will attempt to aerodynamically reduce the forward velocity. To to this he must push far forward on the overhead stick. This push will swing the pilot and the skids back and this will cause the leading portion of the skids to contact the ground first.

If there is still some forward velocity at this time, will the craft not run the risk of tumbling forward?


Perhaps human legs might be better since at the start of the touchdown the pilot's feet will relieve some of the gravitational pull on the rotors. Then the pilot can walk forward, while still applying full forward arm extension so that the partially loaded rotor can continue to exert some rearward thrust.

:noidea:
Dave

Jens
11-04-2009, 10:47 AM
:focus: Rotor brake and parachute.

Counter rotating light weight props might be rather harmless a few seconds after the engine has stoped? I think so.

Maybe a rotor brake is not needed! - Just throw the cute!
With a prop radius of only 1,25m/4ft the cute will come free of the props - can't fail.
Attach to the machine a strong line that the light weight props can't harm, but the strong line can harm the props.

Here we go - rescue paracute and helicopter :first:

Rotor Rooter
11-04-2009, 11:35 AM
Jens,

I have taken the liberty of adding your coaxial picture to the collections on this web page. OTHER: Helicopter - Outside - Extremely Light - Backpack & Foot landing (http://www.unicopter.com/1764.html). If you object to this please say so.


A couple of questions;

1/ Can you elaborate on the rotorcraft in the picture.

2/ It appears to have IVO blades. The disk area and tip speed are important for optimizing the thrust. You are mentioning a radius of 1,25 meters (49").

On this page (http://www.unicopter.com/1774.html) I have tried to obtain the radius of Schoeffman's rotor but am getting two very different radii of 51.3" and 43.4". The maximum radius for Ivo's medium blade is 74"/2 = 36" then add the hub-bar radius of maybe 9" for a total of 45".

Can you help?

Dave

Sita
11-05-2009, 03:50 AM
1/ Can you elaborate on the rotorcraft in the picture.

2/ It appears to have IVO blades. The disk area and tip speed are important for optimizing the thrust. You are mentioning a radius of 1,25 meters (49").


Dave

I think the rotorcraft in the picture belongs to Hugh,one of the guys on the back-pack helicopter forum who's building a Schoeffman.

They are indeed IVO blades,you can contact Hugh for exact numbers.

From memory (!?) the Schoeffman had a rotor diameter of 2.13 meters Dave.

Cita

Jens
11-05-2009, 07:47 AM
The radius 1,25m/4ft/49" was given with an appropriate accuracy for the subject under discussion 'Rotor brake and parachute'.
A rescue parachute in connection with 4m/13ft rotors (as the GEN H4 and others have) is a very different situation, and not workable - unless we have a very effective rotor brake - I think.

Jens
11-05-2009, 08:47 AM
Again an opportunity to focus on a subject, and with little deviation from it, pin point the good and the bad :peace:

The prototype in the picture might look ‘a little non aero something’.
But maybe there are quite a few good things with it – although it needs some more designing – like a gimbal under the rotor etc.

The most central idea in this helichopper, is to use an almost complete chopper (bike/crosser/snowmobile).

Advantages;
1. Very easy to build - or should I say buy.
2. Lots of power.
3. Very low COG.
4. COG right under rotor.
5. Possibility for legs on ground at start and landing.

Disadvantages;
1. Heavy.
2. Long power transmission.

The heavy problem is actually easy solved by just buying more cheap hp’s.
Now we only have 1 real disadvantage and 5 advantages :D
Right?

Rotor Rooter
11-05-2009, 12:12 PM
Cita,

Thanks for the information. Can you provide the link to the mentioned back-pack helicopter forum?

By the way, how is your project coming?

Dave

Sita
11-05-2009, 02:49 PM
Cita,

Thanks for the information. Can you provide the link to the mentioned back-pack helicopter forum?

By the way, how is your project coming?

Dave

hello Dave,

see if I can get a link,


http://uk.groups.yahoo.com/group/Back-Pack-Helicopter/

regards,
cita

My project is on the back burner for now.Have other things on my mind (boating) that eat up all my spare time.
With winter arriving,probably agood time to take things up again.

Rotor Rooter
11-05-2009, 04:06 PM
Cita,

Thanks. The link works.

Dave

tyc
11-08-2009, 07:38 AM
The more I think about it, the more I keep coming back to the work Schoeffmann is doing. The man just might be onto something but I definately do not like that landing gear. Even when zipping along at 3 meters or so off the deck that engine can quit and with that tri-pod set up he is currently using, a "run-on" landing appears to be essentially impossible - ergo, complete disaster. A more conventional skid landing system would I think be far more practical, which brings me right back to a what is essentially a mini-helicopter, an inexpensive, simple, basic, straight forward helicopter, while capable of flying much higher, it is in fact intended to be flown only 2 to 3 meters above the ground, which wnen you think about it, that's not a bad idea at all.

Anyway, just my two cents for what it's worth.

tyc

Rotor Rooter
11-08-2009, 08:17 AM
From Yahoo:

"Mr.Schöffman's heli-pack weighs roughly 35 kg! [77 lbs total] I've seen this machine and I can assure you that there is not one single part which is not needed."

Deconstruction.http://www.unicopter.com/ThumbsUp.gif

Jens
11-15-2009, 04:14 AM
:peace: :first: :plane:

Or?

tyc
11-15-2009, 05:55 AM
Jens;

Saw that drawing of yours. Not bad. Not bad at all.

Was wondering, why use the air compressor to drive the rotors? Can you not get the same or sufficient volume of gass from the exhaust of a suitable sized 2 cycle engine? Might save some weight by going this route. Also, if I may suggest, keep the front wheel but consider replacing those rear wheels with skids; lighter and less moving parts but over all, not bad fella, not bad at all.

tyc

Sita
11-15-2009, 08:03 AM
Jens;

Saw that drawing of yours. Not bad. Not bad at all.

........................
tyc



150 kg-80 hp-3 m rotor diameter ?

Hiller Rotorcycle:
130 kg-40 hp-full cyclic/collective-autorotation etc...

both a far cry from Schoeffman:

35 kg-30 hp-2.13 m rotordiameter

Jens
11-15-2009, 10:01 AM
We could also take the additional labour and make a stick version - preferably with push pull cables.

This gives a very interesting control opportunity - in my opinion.
Here it comes:
If we attach the stick, with an easy release button, to the upper part of the body, the rotor would follow the direction we lean the body.
This might be precise enough and very useful, when you drive on the beach or something - WITH BOTH HANDS ON THE BIKE and still some control of the rotor!

This stick and rotor control is probably not fast and precise enough when fully in the air.

Rotor Rooter
11-15-2009, 03:55 PM
Jens,

The follow is some what similar to yours and might be of interest to other weight-shift helicopter developers.

This page shows the nearly complete Coaxial power-train design (http://www.unicopter.com/1842.html).

This page shows the follow-on Bilateral power-train designs (http://www.unicopter.com/1841.html).

Both power-trains are designed to take 4:1 ratio gears for use with IVO propellers and 6:1 ratio gears for use with larger blades. In fact the Coaxial gearbox and the Bilateral gearboxes are almost identical. The primary difference is the need for two outer housings for the Bilaterals. Half of the Coaxial's 'guts' are then moved over to the second housing. Then a couple of joints, a X-shaft and X-bracing are added.

All configurations have 2 motor, which drive both of the rotors. These motors might be replaced by engines, particularly in the Bilateral configurations.


Now to get closer to your idea:

The effort to weight-shift in the pitch change direction should be the same for all of the above configurations. However, the rotational inertia will be greater for the wider spaced rotors in the roll direction.

from web page A175; Rotor to Rotor Mechanical Torque Coupling:
~ Coaxial: There is no need for a coupling because the crown gears of the two rotors are directly interlocked by the pinion gears.
~ Intermeshing: A pair of universal joints. The two rotors will have fixed and identical angles off of the vertical.
~ Interleaving: There may not be a need for a coupling. The two rotors can be connected by a straight through shaft from motor to motor.
~ Side-by-Side: A pair of constant velocity joints. The two widely spaced rotors may require the incorporation of the lateral tilt mechanism. This is because the two joints will not always have identical obliquity angles.


Now to get very close to your idea:

To roll to the left the pilot weight-shifts to that side. As he shifts the counter-force on the control bars cause the left rotor assembly to tilt to the left. This results in a situation where the right rotor is providing all its thrust vertically whereas the left rotor is providing slightly less vertical thrust plus some small thrust in the direction of roll.

In other words the independent lateral gimballing of the rotor heads in conjunction with the weight-shift proved the roll moment.

The intent was to patent the laterly assisted weight-shift, but hell, it's a freebie for all wan-a-be microlight helicopter developers who are going to give recreational rotorland its next product. ;)

NexGen recreational rotorcraft are coming to a small pad near you!


Dave

Eli-sir
11-15-2009, 10:22 PM
Jens, if you use a tip jet system with compressed air you don't need a coaxial configuration, a single rotor is sufficient. See for example SO1221 Djinn helicopter or Dornier DO32.

Rotor Rooter
11-16-2009, 11:02 AM
Jens, if you use a tip jet system with compressed air you don't need a coaxial configuration, a single rotor is sufficient. See for example SO1221 Djinn helicopter or Dornier DO32.
Ideas inspire ideas. In the theme of the old TV series 'Connections' (http://en.wikipedia.org/wiki/Connections_(TV_series)) here is a possibly unconsidered idea that some progressive conceptualist might wish to consider.

Take the single-blade rotor concept. It is not capable of reasonable forward flight and it requires a means of countering it's torque.

Take the previous thread on this site where the University of Maryland students used ducted fans to power a single-blade rotor, while also countering the torque and provide a potential means of having reasonable forward flight speed.

IMHO. the ducted fan will prove to be inefficient. However consider having only one so-called tip jet and moving it to the location of the counter weight of a single-blade rotor. This will allow the blade to be thiner and the rotor portion of the tip-jet paraphernalia will simply be a deduction from the 'dead weight' of the necessary counterweight.

The majority of the weight can stay below the gimbal with the pilot. Therefore the weight of the rotor should be very light.

Could this be one more means of having a 'back-pack type' of helicopter that is lighter and cheaper than a gyrocopter??? :first:

The Rotonauts :argue: the Gyronauts

Just provoking thought or confrountation. :)

Dave

Sita
11-16-2009, 10:56 PM
Ideas inspire ideas. .........................................However consider having only one so-called tip jet and moving it to the location of the counter weight of a single-blade rotor. This will allow the blade to be thiner and the rotor portion of the tip-jet paraphernalia will simply be a deduction from the 'dead weight' of the necessary counterweight.


Dave


Dave,
moving the tip jet to the location of the counter weight would mean that it needs to be more powerful (bigger ?) due to the smaller momentum arm.
The gain in weight saving on the counter weight part and the main rotor blade might be lost due to the gain in weight because of a bigger jet-bigger engine-bigger blower etc...I think:sorry:

Rotor Rooter
11-16-2009, 11:30 PM
Cita,

You could very well be correct.

The thinking is/was that the streamtube produced by this thruster would have a larger diameter than a tip jet, but it would produce a lower induced velocity.

Something like a compromise between a normal tip jet and this idea. (http://www.unicopter.com/0002.html) :noidea:


Dave

Jens
11-17-2009, 08:59 AM
…knowing I may very well be able to take advantage of it or something like it if Schoeffmann or that fellow "jens" decide to market their products….
I instantly had the thought, that THIS HoverBike has an appeal and a market greater than other hover machines.
But I decided to post it, because I might be able to build a Schoeffman with a Wankel engine, in my current situation, but not something like the HoverBike.
It will take quite some work and dedication before the first will fly.
But now somebody else will build a HoverBike - right?


....Can you not get the same or sufficient volume of gass from the exhaust of a suitable sized 2 cycle engine?
......but over all, not bad fella, not bad at all.
Exhaust…. Then we go into hot air!
One of the great features with the HoverBike is no mechanical or other special problems :peace:

It might be a winner.
Only one real concern – noise!?

Sita
11-18-2009, 12:12 AM
Cita,

You could very well be correct.

The thinking is/was that the streamtube produced by this thruster would have a larger diameter than a tip jet, but it would produce a lower induced velocity.

Something like a compromise between a normal tip jet and this idea. (http://www.unicopter.com/0002.html) :noidea:


Dave

Hello Dave,

I think compromise is the worst enemy of any design because it allways leads to decisisons which possibly highlights the "shortcommings" .
A concept on the other hand can have as much shortcomings as thinkable because it usualy only shows a direction into which the design can evolve.
The trick is to find the "perfect" marriage between idea-merrit and need at a certain moment.
Schoeffmans concept is extraordinary because it shows that building a very light,simple helicopter can be accomplished with limited means.
Is it perfect ? ...Hardly, but it is doing what is was designed for,taking a person into the air and have some fun and this is a proof of concept in my view.
It took Schoeffman several years to get what he has at the moment and if we're honest,there's no "high technology" involved in his machine whatsoever.
What I'm trying to say is that it's not so obvious to incorporate several "new ideas" into a concept and make it work.
The time that investors money can be found with just an idea and a set of drawings to build a prototype is long gone I guess.
So the only alternative is to build it ourselves and prove that it works and for that, it needs to be simple. Everyone who has ever build something knows how difficult it is to go from drawing board to the actual goal and apparently simple things like a "rotating seal" might prove an impossible barrier to take and a possible failure of the whole project.
Conclusion:Schoeffman is a damn clever guy !!!! Dream it, build it,fly it !!

Cita

Jens
11-18-2009, 08:39 AM
Jens, if you use a tip jet system with compressed air you don't need a coaxial configuration, a single rotor is sufficient. See for example SO1221 Djinn helicopter or Dornier DO32.
Yes and no.

Yes, if you want to invest in a rotor head with cyclic (and collective) pitch. Without cyclic pitch you can't tillt the rotor.
No, if you prefer a fully rigid rotor head and blades with a simple gimbal underneath.

And yes a single tip driven rotor, if the goal was a HeliBike.
In helicopters practically everybody prefer a rotor head with cyclic and collective pitch, because it gives precise and instant control in all directions, and autorotation capability.

And no, because my goal is a HoverBike.
For a hovercopter you can get away with a fully rigid rotor head and blades – presupposed that you can unload the ship with your legs.
You also get a smaller diameter for coax witch has some importanse for a hovercopter.

I would like to know more about the Djinn compressor, noise level etc..
And in general what efficiency one can expect with the use of a ‘cold’ air compressor.

Rotor Rooter
11-18-2009, 11:30 AM
Schoeffmans concept is extraordinary because it shows that building a very light,simple helicopter can be accomplished with limited means.

Is it perfect ? ...Hardly, but it is doing what is was designed for,taking a person into the air and have some fun and this is a proof of concept in my view.



Thanks Cita for your valued thoughts. . . http://www.unicopter.com/ThumbUp.gif 100%.

My 'real' project is the Electrotor-Microlite (http://www.unicopter.com/ElectrotorMicrolite.html). It is Schoeffman's idea, but using electric power. The build-time is taking longer than expected, which is partially due to the boringness of calculations and detail drawings. It's eventual purpose is to serve as the work platform for progressively pursuing a number of intriguing and challenging upgrades, which are listed here (http://www.unicopter.com/Electrotor.html#Objectives).

The posting on other concepts is to participate in keeping related conceptualizations alive and flowing, and also as an enjoyable relief from the boring detail sh-t. :tape:


Dave

Jens
11-18-2009, 12:46 PM
I was looking for the Rotary Wing Forum rules, but I did not find them.
I would have made a link, just for those who think they need to read them again.

But on the net I found these pieces:

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Sita
11-18-2009, 03:23 PM
Yes Dave,

electric seems to be the trend for future transportation so I guess you're on the right track.
The Electrolite Microlite has all the "goodies" from Schoeffman but it's power source will be more reliable and "safer" than Schoeffman's two stroker (although he had never serious problems with it as far as I know).
The last two decades there has been a boom in electrical power management systems so that looks promising for the Electrolite Microlite.

Do you have any idea in which direction you're looking to solve the rotor blade "problem" for the Electrolite Microlite ? (off the shelf propeller blades-Fleck blades etc...)
Some 30 years ago,if my memory serves me well,a Belgian guy developed a very clever way of making all aluminum rotor blades.
It had a folded sheet serving as a spar with the one piece skin bonded and rivetted to this spar.
I made a small test section of such a blade with a Naca 8-H-12 airfoil and the stiffness and light weight was amazing.

You're absolutely right Dave that sometimes we need to keep the grey matter in our skull alive with idea's and thoughts which might look bizar at first glance.

Keep us posted !!!

Cita

Rotor Rooter
11-18-2009, 06:08 PM
Do you have any idea in which direction you're looking to solve the rotor blade "problem" for the Electrolite Microlite ? (off the shelf propeller blades-Fleck blades etc...)We will be producing carbon composite blades. This is the page on the foam core. (http://www.unicopter.com/1776.html) Unfortunately, the person cutting the foam was not producing acceptable cores. We got quotes on having a bunch cut on a CNC machine. The price was good, but.....

Before getting tied up in too many aspect of the craft at the same time, it was decided to just buy two 3-blade 74" diameter propellers from IVO. This should get the craft into the air. Then the fun stuff can begin.

Dave

Eli-sir
11-18-2009, 10:11 PM
I would like to know more about the Djinn compressor, noise level etc..
And in general what efficiency one can expect with the use of a ‘cold’ air compressor.

Jens,
about ten years ago, when I was in France, I have seen a Djinn in flight.
Unfortunately ten years ago I don't have a digitali camera, so the images are only in my mind, but I can assure you that are fantastic images.
The noise of the Djinn is very impressive, almost indescribable, just for example if you know the SA315B Lama and if you know his "sound"... well the "sound" of the Djinn in two times...

For the efficiency I don't have any ideas, I have try to find for more time documentations on the Djinn but never, I have only three pages of an old italian magazine that describs summarily this helicopter.

My dreams is built a single rotor tip jet helicopter, and the big problem is realize the rotor blades with the air passage (Djinn's blades are very complex), for the moment my efforts are concentrated in a Shoeffman type hover copter... maybe in a future...

P.S.: This evening I will put here the three pages with Djinn description.

Rotor Rooter
11-19-2009, 12:38 AM
for the moment my efforts are concentrated in a Shoeffman type hover copter

Eli-sir,

Schoeffman remains close to the ground and the amount of area he covers is quite small. If this is the objective of others then they might consider an electric drive, which is powered by an electrical cable from a ground based generator set.

It can't get much simpler than this. (http://www.unicopter.com/1827.html)

Later, if one wanted to get adventuresome, the generator set could be put on a pickup truck, which would be driven by a friend or two.

A small capacitor or battery pack could be included on the 'hover copter', for use during a descent and landing, should the cable become disconnected.

Just throwing ideas up in the air. :rapture:

Dave

Eli-sir
11-19-2009, 08:49 AM
Unfortunately the file with a little description of Djinn is very big, so I don't can attach it here, but I can send it via e-mail at interested people.

Dave (Rotor Rooter), electric hovercopter with ground genset is a beautiful idea, I have a little helicopter model, Hirobo XRB, that use this system, it has a 2.5mt cable between helicopter and "transmitter". It use a switching power supply that convert 230 Vac into about 20 Vdc.

For you what type of electric motors can be used in an electric hovercopter with ground genset? The Shoeffman's type has 28 Hp, and an electric motor with this power is big an heavy, a solution can be use an high frequency motor with inverter... what do you think about this?

Eli-sir
11-19-2009, 09:18 AM
This is my helicopter model with cable...

Eli-sir
11-19-2009, 11:02 AM
Jens, here a low resolution pages of Djinn's description, on 2nd page you can see the internal structure of blades, very hard to reproduce it!

Sita
11-19-2009, 12:00 PM
..................the internal structure of blades, very hard to reproduce it!

Doblhoff used steel streamline tubing as hollow leading edge section to transport compressed air to the rotor tips.
A lightweight core was glued to this steel section to form a NACA 00 series airfoil.

Cita

Rotor Rooter
11-19-2009, 01:16 PM
For you what type of electric motors can be used in an electric hovercopter with ground genset? The Shoeffman's type has 28 Hp,

Reliable motors with low weight and good cooling are not there yet. But they are coming.

Interconnecting two of these (http://www.unicopter.com/1584.html) will provide a maximum of 40 hp for 3,600 grams, plus limited duplicity;
BUT THEIR LIFE AND RELIABILITY WILL BE EXTREMELY LACKING.

Dave

Eli-sir
11-19-2009, 10:16 PM
...these will provide a maximum of 40 hp for 3,600 grams...
Dave

Dave this electric motors absorb over 300 Amps with a low tension 10-14 Li-Po battery in series, for this current the section of electric cable is very high so also the weight of this cable is very high ad the hovercopter must be able to lift from the ground at least 2 meters: for this operation we lost more power.
I think that is better to use an high frequency electric motors (electrospindles motor for example http://www.teknomotor.com/) with an input of 230-380 Volts, so we can reduce the current at equal power and consequently the cable section (see also cable weight).

Willmer

Rotor Rooter
11-20-2009, 11:03 AM
Willmer your point is a valid one; especially when dragging a cable around the ground. Supporting your concern is this crude initial work (http://www.unicopter.com/ElectrotorMicrolite_Wiring.html) that considers the diameter of the back tube from the motors to the batteries.

Planetary reducers are light and can have double or triple reduction. Can you think of other light-weight, high-voltage motors with reasonably good reliability?

Perhaps like you, my desire is for the Electrotor ~ MicroLite (http://www.unicopter.com/ElectrotorMicrolite.html) rotorhead assembly to be one contribution, amongst those from other people, used for experimenting with interesting rotorcraft ideas. The size is small enough that the craft can be controlled remotely for the initial stages of riskier modifications.

The intended followup rotorhead assembly is the Electrotor ~ SlowMo (http://www.unicopter.com/ElectrotorSloMo.html). Its power train will be a slow turning electric motor that eliminates the need for any mechanical speed reduction. This motor will definitely be wound for a higher voltage.

It appears that there could be a large demand for such a craft after the interested pioneers tackle and overcome the challenges.


Dave

Openness, Peering, Sharing, and Acting Globally

leviterande
11-20-2009, 07:10 PM
concerning safety, no one ever talked about protecting the rotors.

since it is more important for these small helis why not include a protecting shroud. that is my opinion but no one has ever thought about it. perhaps because of .. you guessed it: Mr Weight

Sita
11-20-2009, 10:49 PM
leviterande,

you answered your own question,weight is indeed what keeps the rotors from being protected by a schroud.
If we would place a metal tube around each rotor we would talk about over 36 ft of tubing for the circumference only,not how we would attach it firmly to the frame or the rotor itself, which in Schoeffmans case could be done.
A shroud should be over 12 inch wide and a lenght of roughly 6 yard,even in composite material this would weigh something.
A shroud must be designed properly or it would do more harm (aerodynamically) than good.
The shroud,tubing or sheet,must be so designed that it can be taken apart for transportation yet be perfect in shape after each assembly.
Not an easy task I would say.
If protecting the rotors could have been done,Schoeffman would have done it.....I guess.

leviterande
11-21-2009, 05:13 AM
I am well aware of the side effects but still INMHO I believe that it could give some nice advantages... safety.


what one would need is at least three supporting arms stretching from the main mast outwards that can hold a glasfibre composite shroud.... so yeah despite the weight to me at least it is important to have a shroud. there is a solution somewhere

Rotor Rooter
11-21-2009, 08:39 AM
Re: protecting shroud.

Safety must be a primary requirement but perhaps the first questions should be; for who's protection and at what point(s) in the flight profile?


Dave

leviterande
11-21-2009, 10:51 AM
For any nearby people, for any obstacle, object that can some in contact with the rotor.. Furthermore on the lower side of the rotor there should be a grill just to avoid any hand/head contact with the rotor.

Rotor Rooter
11-21-2009, 12:17 PM
leviterande,

Not hitting objects is the responsibility of all drivers.

The pilot will probably be under the rotors with his hands on the 'controls' when the rotors are turning.

It appears that you are referring to bystanders. Perhaps a circle of light roll up fencing, which remains on the ground, is sufficient to keep kids and naive bystanders away.

leviterande
11-21-2009, 02:57 PM
leviterande,

Not hitting objects is the responsibility of all drivers.

The pilot will probably be under the rotors with his hands on the 'controls' when the rotors are turning.

It appears that you are referring to bystanders. Perhaps a circle of light roll up fencing, which remains on the ground, is sufficient to keep kids and naive bystanders away.

Let me ask you , have you seen a helicopter crash where a helicopter tips over? .. everything is intact and the people inside the heli are not injured during a crash until the helicopter rips over and the rotor tips hit the ground. DISASTER break loose! there are just too many such types of accidient and I really and truly believe it is a very unfortunate thing to witness. ..

it is enough if you even are 1 ft off the ground and you can die if the rotor hit the ground. putting a shroud might add weight but my point is just to let people think about that as I have never seen any such considerations taken in any helicopter.. well, that is perhaps because of the many other faulty designs included into a heli

brett s
11-21-2009, 04:23 PM
If you hit the ground a blade shroud won't stop pieces from flying either, unless it's built so heavy you couldn't possibly fly in the first place.

There's usually a reason behind things, look at the designs that are successfully flying & figure out why before trying to reinvent the wheel. It'll be a lot less frustrating, and cheaper if you actually intend to build something.

leviterande
11-21-2009, 05:25 PM
If you hit the ground a blade shroud won't stop pieces from flying either, unless it's built so heavy you couldn't possibly fly in the first place.

There's usually a reason behind things, look at the designs that are successfully flying & figure out why before trying to reinvent the wheel. It'll be a lot less frustrating, and cheaper if you actually intend to build something.

looking at the designs and figuring out why they are out there, are the reasons that make me believe that we unfortunately should Reinvent the wheel cuz that earlier "wheel" was perhaps a bad one. there are many reasons but that will be out of the scope of the forum;). I know the reason helicopters are complex because of the base of their design requires these complexities that are nessecary for todays helicopter`s efficieny, function, safety etc. However, todays helicopter lacks a lot and there is alot to be changedin order make vertical takeoff landing machines closer to "cars"

just a thought, steam train`s pressuretanks had a safety factor of 40, a lot more than needed for safety. todays machines and on the top of the list the helicopter has a much lower safety factor. My plain point is that we should look at the whole thing from the start. No, we dont need to invent the same wheel but maybe "another" safer, simple, better" wheel. That is only my opinion and I am aware that not many agree and that is fine.

Helicopters have evolved since 1500s? why should we stop now, why did the fundemental helicopter design stop at 1947. .. nothing changed. Yes it works and yes it flys with control but it seemed people before that date had the energy and spirit to change for the better. So even if they failed I believe they were making progress. 60 years is maybe a short time? I dont know ..

Sita
11-22-2009, 05:47 AM
.................................................. .................................................. ........
Helicopters have evolved since 1500s? why should we stop now, why did the fundemental helicopter design stop at 1947. .. nothing changed. Yes it works and yes it flys with control but it seemed people before that date had the energy and spirit to change for the better. So even if they failed I believe they were making progress. 60 years is maybe a short time? I dont know ..


Exactly my thoughts too leviterande.
it's not because something didn't work a few decades ago that it couldn't work today but there's a difference between technology and laws of nature.
We cannot change the laws of physics and Newton's third law will remain Newton's third law untill other wise proven for example.
Never did mankind had so many sources available and never was "thinking outside the box" so restricted as today,weird,very weird.
Failure is not accepted so it's better not to try than to fail...so they tell us.

"There are two things infinite;mankinds stupidity and the universe, but I'm not sure about the latter". A. Einstein

brett s
11-22-2009, 06:40 AM
Nothing wrong with finding a better way to do something, but you can't fix something when you don't understand it to begin with.

That includes technology as well as basic physics, a lot of dreamers make up the rules for both as they go along. It doesn't work that way...

Sita
11-22-2009, 01:19 PM
Nothing wrong with finding a better way to do something, but you can't fix something when you don't understand it to begin with.

That includes technology as well as basic physics, a lot of dreamers make up the rules for both as they go along. It doesn't work that way...


No doubt that your words are correct Bret but......it are the dreamers who lead us to progress,allways has been,allways will be.
Dreamers create an idea and engineers solve the problems to make it work.
The rules for a dreamer are his imagination,the rules for an engineer is science,the rules for an entrepeneur are determinated by the fact if he can predict a match or not between the two.
Creativity is not the privilege of those who earn degrees, it just sometimes makes it easier to materialise a dream.

Rotor Rooter
11-22-2009, 03:02 PM
The rules for a dreamer are his imagination,the rules for an engineer is science.....

That is the relationship that resulted in the Flettner FL-282 (http://www.unicopter.com/0474.html) being such an advanced helicopter. Anton Flettner (http://en.wikipedia.org/wiki/Anton_Flettner) came up with the ideas and Dr. Kurt Hohenemser attempted to put them into to reality, or, give Flettner a reality-check. :)


Dave