Another attempt,back-pack helicopter

tyc

Newbie
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

Dave Jackson
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.
 

tyc

Newbie
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

Guest
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

GyroNew & Paraglider
Stick version.

Stick version.

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.
 

Attachments

Rotor Rooter

Dave Jackson
From dreams to ideas to products

From dreams to ideas to products

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.

This page shows the follow-on Bilateral power-train designs.

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
 
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Eli-sir

Newbie
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

Dave Jackson
Tickling the neurons of those who like to use them.

Tickling the neurons of those who like to use them.

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' 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

Guest
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

Dave Jackson
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. :noidea:


Dave
 

Jens

GyroNew & Paraglider
…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

Guest
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. :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

GyroNew & Paraglider
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

Dave Jackson
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. . .
100%.

My 'real' project is the Electrotor-Microlite. 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.

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

GyroNew & Paraglider
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:

vBulletin Rules
• Multiple or repeated posting in order to increase your post count is not allowed.
• Advertising, spamming and trolling is not allowed

Forum rules - Doom9's forum
3) Keep the focus:
5) Do not spam.
8) No cross posting. Post your message once, to the appropriate forum and nowhere else.
9) Use a title that describes the content of your post.
11) Don't post just to increase your number of posts. If you have nothing to say on a certain matter then don't post.

From Joomla
• Keep all posts on-topic.
• No useless posts. This includes: Thread bumping, … Spamming.
 

Sita

Guest
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

Dave Jackson
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. 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

Newbie
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

Dave Jackson
The Promotion of Ideas

The Promotion of Ideas

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.


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
 
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