Another attempt,back-pack helicopter

Jens,

It is that not unusual for 'inventors' to keep their ideas a secret.

Dave

Hello Dave,

I hardly could call myself an "inventor" (lacking too many skills/knowledge) but I do have a few ideas !!

Sometimes a forum is the best place to filter the weak points out of it,sometimes it's not.

I appreciate the "discussion" for example about wether or not to use an additional landing gear for a BPH, even if the tone of the arguments tends to be somewhat negative and/or sarcastic,both from me and the "opponents", but at least it touches the technical aspect and therefore should be regarded as positive.Wether or not I take the arguments into account in the end is my decission...and responsability.

This thread is about the back-pack helicopter concept.For some this concept has merrit,for others it's a stupid idea.

According one of the Wright brothers the helicopter idea was stupid/useless (don't remember which one) because a balloon could do effordlessly what a helicopter was trying to achieve.As stated on this forum,they knew what they where talking about.
Cita
 
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Here’s a backpack that I expect all you hardcore fans know well.

I doubt if this thing ever left the ground under its own power.
 

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Cita,
I think they are very simple questions. And feel free to answer them or not answer them.

Are you designing a BHP? - I mean now, 2011.
If yes, can and will you show us how far you are? - I mean here in Rotary Wing Forum.
 
Here’s a backpack that I expect all you hardcore fans know well.

I doubt if this thing ever left the ground under its own power.

Hello Chuck,

Good O'll Gene (Gluhareff) used his back-pack helicopter to promote the jet engine he invented.
He sold plans for that engine but left crucial information out of it as was discovered years later by a few guys of the Pulse jet forum.
No way one could build the engine performing like the claims made in the plans following the same plans.

I have old video footage of this helicopter but it's not very clear if the tether from a high crane "helped a bit".It sure shacked badly during start up !!
He made a two bladed version and a flying platform using the same type of engine.
The MEG-1X shown used a 13 lbs static thrust engine,later changed to a 25lbs thrust engine.
I have my doubts too that it ever has flown under it's own power.


Cita
 
Hello Dave,

I think Kalle (leviterande) has a valid point here regarding affordability of an idea.
We are all limited I guess by our financial resources and in some cases this can even be regarded as a plus point !!
Let's assume, just like Kalle, that we would take the task of designing a "virtual back-pack helicopter" which "should" be affordable by the "average hombuilder".
Imagine we have an engine in the 2/1 ratio regarding power (hp)/weight(kg) and let's say that this engine is capable to produce 40 hp without "strectching it to the limit" most of the time.
An average pilot weight of 90 kg (people have "changed" over the years !!)
and the assumption that the craft iself must not exceed 50kg total weight.
So we have:
40 hp/20 kg (engine)
90 kg (pilot)
50kg ('dry" weight of the heli)
150kg total take-off weight (10kg reserve)

How would you guys proceed from here on with these parameters ?

Cita


No reply so far so I'll try to answer my own question.

For the moment an additional landing gear is not considered by me so "safety" must come from somewhere else,autorotation.
I picture a co-axial design.
Most light gyrocopters use a rotor dsicloading of about 8 kg/m2
With the figures we have,150kg max take-off weight, that would mean that we need about 18.75 m2 of combined rotor disc area.
18,75:2=9,37
9.37m2 rotor disc gives a diameter of 3.45 meter which seems acceptable for such a contraption.

Is 8kg/m2 rotor disc loading a realistic figure for a BPH ? I don't know but we need to start somewhere.

Is it reasonable to assume that both rotor discs in a co-axial will perform "normal autorotation duty" ? Again,I don't know.

Full cyclic and collective might be the only option to achieve this autorotation so let's assume that whe have this incorporated into the rotor system.

Gentlemen,

take your rifles out and let's start the shoot out !!:drama:

Cita
 
I’ve had several incidental encounters with backpack and similar helicopters, Cita.

When I was a very young student, I worked a second shift for Boeing, compensating flux valve compasses. This required a remote area stripped of all magnetic materials.

The location was a former military area of Boeing Field in Seattle, mostly abandoned barracks buildings, mess halls, etc. The flux valve was mounted on an aluminum tower, making 1 revolution/hour and plotting the error curve on a chart recorder. Once per hour, I had to adjust the compensation and make another run. I had lots of time to explore.

I found in one old military building a pile of stuff that was the remains of Horace Pentecost”s Hoppicopter experiments. I’ve seen film clips in recent years of Mr. Pentecost flying his device and it looked to be quite a chore.

http://www.vintageseattle.org/2009/03/24/and-now-horace-pentecosts-hoppicopter/

Years later, an early Sunstate Rotor Club member, Bob Farmer returned from Texas and related his experiences as the test pilot for the McGill Pinwheel H2O2 helicopter.

You probably have this site bookmarked:

http://www.tecaeromex.com/ingles/libe-i.htm

Bob said he considered it too dangerous to fly the human legs for landing gear model, having visions of himself in the center of a ball of fire if he ever stumbled.
 
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Hello Chuck,

thanks for your remarks regarding the BPH concept.

Is the footage of the Hoppicopter available somewhere on the internet ?

Probably not because it would have "popped up" on youtube or the like I guess if it was.

I know the guy who made the renderings for the peroxide helicopter (the one from Mexico by Juan Lozano) and indeed, being a hard core fan, I know the McGill helicopter also.

I'm trying to move on beyond the landing gear dillema on this forum but this seems to be an impossible task,it's being brought up time after time no matter what.
Without trying to be rude to you Chuck or any one else (giving one or two exceptions !!) who commented on the BPH concept,it seems to lead to nowhere.I'm getting fed up with answering the same subject (landing gear) over and over again,time after time.
Everybody thinks that they bring up something new to me,some of you with the best intentions no doubt about that, when the landing gear/human legs subject is presented.
Being interested in the BPH for more than a few decades I can "break the news" that this isn't the case.It may be dissapointing to some of you but nobody on this forum presented things I haven't heard before regarding the landing gear.
The logical conclusion must be that most of you are right and I'm wrong,so it be.

I'm not going to reply to any of the landing gear ramblings anymore but gladly discuss opinions about other technical aspects regarding the BPH.


Cita
 
"The Helicopter Law; "Whatever helps hover, hurts forward flight, and whatever helps forward flight hurts hover." ~ Prouty, in Rotor & Wing, Jan 99


If hover is the paramount requirement and slow 'cruise' is a side benefit, so to speak, then the VTOL requirement must be looked at in a totally different light, IMO.

From an aerodynamic perspective, axial thrust must be everything. Transitional flight is a side-show. The planform etc. of today's rotor-blades becomes somewhat irrelevant. The propeller and the early airfoils are the relevant ones because they are and were only concerned with optimum thrust (lift) for minimal power.

Obviously, they exclude the possibility of autorotation.

Therefore, the next, and more difficult, objective must be that of circumventing the need for autorotation. It must also include the ability to hover just in or just out of ground foot-contact, with very fast control responses. And there is more.......

On the possibility that a candidate for the Darwin Award is at the helm, ideas such as slow turning low-inertia rotors will help. Braking of the rotor may help (which is simply regeneration on an electric drive). And there is more.......

lightbulb%20idea.gif


Cita,

A reply will be coming. Technical stuff takes a little longer.


Dave
 
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Hello Dave,

that's very innovative thinking to say the least!!

Correct me if I'm wrong on this but as I understand it are you suggesting to "replace" (it's not the correct word but my English is "somewhat" limited) "laws of nature" -autorotation, by technical means ?

Do away with "the need" of autorotation is a challanging task but perhaps that autorotation as a safety measure has been so long around that nobody cared to look for another option,taking away the need for autorotation.

This technology is probably way beyond my capability but I'm interested to hear your thoughts on this.

Cita
 
Cita,

Re your post #705. My response was post #705. Others may wish to respond.

Your question;
How would you guys proceed from here on with these parameters ?
Sounds like a request for someone to design the ultimate back-pack helicopter. The army would love a foolproof answer to this also. Here was one such attempt that went nowhere. Kamov Ka 56


It can be arguably said that Schoeffmanns back pack helicopter approaches the ultimate, EXCEPT it does not have autorotation, NOR an alternative to autorotation such as 'assured power'. There have been numerous attempts but no one yet has found the holy grail.

____________________________

The convoluted relationship of rotorcraft variables can make simple answers difficult. Perhaps the best approach is to submit the idea(s) on the Rotary Wing Forum, accept the constructive criticism, and then go and try and overcome or circumvent the valid critiques.


You may find the following informative by just reading the text and skipping the math.


A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research

AERODYNAMIC OPTIMIZATION OF A COAXIAL PROPROTOR

Dave
 
Cita,
....are you suggesting to "replace" (it's not the correct word but my English is "somewhat" limited) "laws of nature" -autorotation, by technical means ?

It is an attempt to 'circumvent' an aspect of nature. Heck, very, very few things autorotate.

The Electrotor-SloMo will eliminate the NEED for autorotation, OR provide a powered and controlled exit from autorotation when near the ground (See PS.), OR IT WILL NOT BE BUILT.

So far ~ so good.


Dave

PS. A propeller or a rotor blade with ideal twist may not be able to autorotate, at least not in the same direction of rotation as when under power. This may involve comprimizes, particularly if the rotor was able to get into the vortex ring state while in a vertical descent and not be able to power out of it.
 
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Dave,

what you have in mind is probably a much bigger challange,I'm not saying impossible, than what I try to do.

A lot of people seem to have an opinion about the BPH and a lot of them have knowledge and my only request is that they expose that opinion.

I proposed for example a figure of 8kg/m2 disc loading for the "virtual" BPH and perhaps there are people who think that this is too high or to low.I just like to hear their opinion.
I hope I didn't sound like I was requesting someone to "design" the ultimate BPH for me or anyone else.

Cita
 
Cita, the Discovery Channel ran a series entitled “Choppers” a dozen or more years ago that had clips of nearly everything with rotating wings that had ever existed. One short sequence featured Horace Pentecost and the Hoppicopter. I videotaped it all and some I digitized and stored on hard drives or CDs. I don’t recall whether or not I digitized the Hoppicopter but in any case, I still have the video tapes.

See if the Discovery Channel offers CDs of the Chopper series, not to be confused by a more recent title “Choppers” which is about motorcycles.
 
hey cb, discovery used to have a channel called wings, now replaced with "the military channel" :sad:

Cita, the Discovery Channel ran a series entitled “Choppers” a dozen or more years ago that had clips of nearly everything with rotating wings that had ever existed. One short sequence featured Horace Pentecost and the Hoppicopter. I videotaped it all and some I digitized and stored on hard drives or CDs. I don’t recall whether or not I digitized the Hoppicopter but in any case, I still have the video tapes.

See if the Discovery Channel offers CDs of the Chopper series, not to be confused by a more recent title “Choppers” which is about motorcycles.
 
Cita,

Assuming your gross weight is 150Kg [330lb] your disk loading of 8kg/m2 disc loading [1.635lb/ft2] is very close to that of the Ultrasport 254, and it has a very slow descent rate. However, it is a single rotor and you have not mentioned what constitutes your 'disk'. is it the area of 1 disk, the area of 2 disks, the effective disk area based on the vertical distance between the two disks?

Here is similar information on the Gen H-4 Rhyme BDH strap-on

This may be of interest, or discussion, or correction; Backpack Comparison


Dave
 
Cita, the Discovery Channel ran a series entitled “Choppers” a dozen or more years ago that had clips of nearly everything with rotating wings that had ever existed. One short sequence featured Horace Pentecost and the Hoppicopter. I videotaped it all and some I digitized and stored on hard drives or CDs. I don’t recall whether or not I digitized the Hoppicopter but in any case, I still have the video tapes.

See if the Discovery Channel offers CDs of the Chopper series, not to be confused by a more recent title “Choppers” which is about motorcycles.

Chuck,

I found only one dvd regarding the history/development of the helicopter and that was in the "Extreme Machines" series.
The video was made in 1997 and is about 52 minutes long and is called "Choppers".

When you enter "Choppers", your sreen get's floaded with the Teutel "Abbot and Costello twins" !!! Not exactly what I was looking for !!!

Several of the helicopter "Choppers" dvd's from Discovery are offered on ebay for a few bucks so I think I order one of them and hope that it contains the footage of Pentecosts Hoppi-copter.

Thanks Chuck !!

Cita
 
No reply so far so I'll try to answer my own question.

For the moment an additional landing gear is not considered by me so "safety" must come from somewhere else,autorotation.
I picture a co-axial design.
.........................................................
Cita

Dave,

I'm not sure that I understand what you mean.
You mention the 150kg total weight and 8 kg/m2 so it cannot be other than at least two main rotors.

To keep the diameter acceptable for ground handling I had to choose the "more than one main rotor concept and opted for the co-axial which with the 8kg/m2 discloading would give me a diameter of roughly 3.50 meters.

I'm only trying to get a "general view" of the "possible" BPH figures (autorotation capability-hp requirement-solidity ratio etc... etc...) and see if they could be matched with "ordinary technology" available to the "hobbyist".

Cita
 
some russian BHP

some russian BHP

I found some russian sketches on russian helicopter forum.Why not?

Jetman
 

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The Discovery Channel dvd "Extreme Machines-Choppers" is seemingly not available for region 2.
The Australian version I intended to buy is for region 4 so useless for me.

Is there any other way I can get to see that Hoppi-copter sequence.Anyone can help ?

Cita
 
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