First jump takeoff in France

Jean Claude

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I piloted gliders C800, Bijave, C 310, airplanes Piper J3 , PA 28, Jodel D117, DR 220, Cessna 150, C
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The total mass of the current rotor of Michel is 40 kilograms, each composite blade weighs 10 kgs
Let me evaluate very roughly the possibility of takeoff with no run by pitch setting jump:
Assuming the rotor pitch is adjusted abruptly to lift the weight of the gyrocopter in hover, the time during which the rotor energy due to overspeed will be available depends on the average power input:
For an 8 x 0.2 m rotor the power input is about 20 kW (IGE) at 450 rpm, while the stored energy is 0.5* I *(ΩMax^2 - Ω min^2) or 50 kJ if I = 100 kg.m2, Ω Max = 47 rd/s, Ω min = 35 rd/s
So t = Estored / Pabsorbed = 50 kJ / 20 kW = 2.5 s
If the horizontal speed required to hold the level is assumed to be Vmin at rrpm min and the propeller thrust (2000 N) gives an average horizontal acceleration of 6.5 m/s2 on the 300 kg mass, the forward speed will have reached VH = 6.5 m/s2 * 2.5 s = 16 m/s just required when the rrpm will have decayed to that of the autorotation (Ωmin). The flight can then continue in full autorotation.
In this scenario, there is not really a jump, but a continuous slope from the stop.
A small jump is possible if we take into account the transient increase in lift due to the more slow progression of induced velocity.
But I not knows make.
 

Eric S

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The Cartercopter jump-takeoff Butterfly achieved dramatic vertical takeoffs (Butterfly footage begins at 1:57):


It did so by adding over 20 lb. of depleted-uranium tip weights to the blade tips. This amount of extra mass, as reported by Rusty Nance (gyro test-pilot extraordinaire), made the rotor very sluggish in its response to control inputs.

This makes sense. The amount of force it takes to make a rotor change its orbit (respond to cyclic control inputs a/k/a precess) is determined by the blades' mass, among other things. The force to accomplish this comes from the lift of whichever blade's pitch is increased by the cyclic control input. A blade of given dimensions and RPM is going to make X pounds of extra lift when pitched up by Y degrees of cyclic input. If the rotor is unusually heavy for its size, this Y pounds of force will be inadequate to tilt the rotor disk promptly. Cyclic response will be sluggish and control forces will be high.

The way out of this trap is to make the blades wider or to add blades. Most jump-takeoff gyro builders have done so, e.g. the Boyette-Degraw LFINO used, IIR, double tip weights and three Dragon Wings blades instead of two.
I'm going through this thread again b/c it is SO exciting and interesting.

Anyway, I took the gyro repairman class from Robert Stark in Olney, TX years ago and the Carter Copter monstrosity was in his hangar. I did a slight see-saw movement of those enormous rotor blades to check the flexibility (about "normal" by the way) and was surprised at how heavy they seemed. Mr. Stark said they weigh over 500 lbs.!
 

Eric S

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Michel is a former french air force mechanic and passionate amateur gyro builder.
Please, PLEASE ask him to wear a helmet during his experimenting and test flying, just in case. We need him to be around long enough to get this project perfected so I can have one too someday. ; )

Eric
 

Grodou

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Was my first comment to him after he started to explain his research on our french forum... He kindly declined any form of helm because of claustrophobia ! 😉
 

Eric S

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When I zoom in on the picture...
I sure would like to stand on a ladder and stare at that rotorhead in person and see how the release works and watch it all move.

For example, I've always know what a governor does, but not specifically how they worked. I found a youtube video that explained it all in simple language and a sketch for steam engines, so I think I generally understand how Michel is using the weights to regulate RRPM, but to actually see it in person...

If he was in the US I'd offer to help.
 

Eric S

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I'm impressed.
What some people don't understand is that Michel's machine is a true jump gyroplane.
Dick's aircraft is a Gyrodyne which will have enhanced performance on take off and flight because the rotor is powered during takeoff and flight.
Michel's machine is very inspiring and a work of genius.
Jake,

Are you inspired enough to fire up your lathe and get started? I know you've considered a jump gyro as a project. Let me know if I can help.

Eric
 

Tyger

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Was my first comment to him after he started to explain his research on our french forum... He kindly declined any form of helm because of claustrophobia ! 😉
"Was told he should be wearing a helmet but refused... he was air taxing and caught the skid while traveling sideways resulting in a dynamic rollover under power. Should have got up and walked away but due to lack of wearing a flight helmet, received head trauma which resulted in his passing."
 

kolibri282

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Quote: He kindly declined any form of helm(et) because of claustrophobia ! /Quote
Everyone in the forum would surely feel great pain if the rotary wing community would loose a great designer and builder like Michel to an accident of the sort that Tyger described. Claustrophobia indicates that he perceives a helmet as something that cages him in. Perhaps he could work on trying to think of it as a motherly womb that protects him from the evil of the world. (Sorry if that sounds a touch too touching, I couldn't find any better way of saying this)
 
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kolibri282

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Jump start is a highly complex thing and there are some practical aspects of it that Michel could perhaps elucidate for us. The simple analysis that JC presented in #121 gives some ball park figures but the procedure is probably much more complex. At the end of the jump the aircraft should ideally have a forward speed and a disk angle that allows steady forward flight, i.e. the disk must be tilted backwards such that the rotor operates in sustained autorotation. If that is not achieved the aircraft would loose height, which is obviously not desirable. Since the required disk angle becomes smaller with increasing forward speed it seems desirable to end the jump with the maximum attainable forward speed. To this end I would assume that on the ground the disk is tilted slightly forward because at 300kg gross weight an angle of e.g. 15° would add an accellrating force of more than F=m*g*sin(15°) = 762N to the 2000N that JC assumed in his calculation. This would be a bit different from the sequence that René described.

Quote: Position du manche et palonniers au neutre /Quote

Perhaps one of the French members could ask Michel about that.

Thanks

Juergen
 
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gyrojake

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Jake,

Are you inspired enough to fire up your lathe and get started? I know you've considered a jump gyro as a project. Let me know if I can help.

Eric
Already started.
That's a long ass drive every morning and the coffee would be cold by time you got here !!
 

Smack

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I would like to see the 'constant speed' feature eliminated, but keep the variable pitch for the jump.
Unless I'm missing it, the constant speed is only useful for low G situations (that I try to avoid anyway), but it might cause undesired affects at high G (turns). Wish Michel would test that flight regime.

I've been pondering this from another angle, too; if low G decreases rotor blade pitch, that would decrease one form of drag (is that balanced by the increase in RRPM?), and that would allow higher speeds if (IF !) another form of lift were found to make up for the decreased rotor lift (I'm making an assumption that constant speed is not constant lift force), such as a wing.
CarterCopter slowed the rotor rotation speed to increase forward speed, the regulator would decrease pitch (drag) for a potential forward speed increase, if I understand correctly.
 

Tyger

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Claustrophobia indicates that he perceives a helmet as something that cages him in.
These days there are a lot of reasonable helmets that masquerade as ordinary hats, e.g.
I shouldn't think those would be the least bit claustrophobic...
 

Martin W.

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I would like to see the 'constant speed' feature eliminated, but keep the variable pitch for the jump.
.(snip)
Hi Smack .... I see it differently ... the "constant speed" aspect was not the purpose ... a jump rotor was ..... (And to me) eliminating the "governor" would defeat the whole purpose

As it is , it is a very simple system and all the pilot has to do is push one button and away he goes.

Otherwise a pilot operated collective would be required , or an electric solenoid to induce takeoff pitch , which would require the pilot to also release the pitch after the jump is in motion , and timing would be critical.

Let me put it another way .... the beauty of Michel's system is that the pilot pushes the button for takeoff ... pitch is at maximum required ... then as lift and drag begin to slow the rotor down the governor automatically begins to reduce pitch to gyro mode .... it is an ingenious way to attain a smooth transition that is automatic and without pilot action.

I explain that poorly and I could be wrong
Interesting concept and conversations . thanks.
 

WaspAir

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On the articulated A&S18A, the pitch is reduced automatically through pitch-cone coupling (delta-3 hinge)
 

Smack

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Hi Smack .... I see it differently ... the "constant speed" aspect was not the purpose ... a jump rotor was ..... (And to me) eliminating the "governor" would defeat the whole purpose

As it is , it is a very simple system and all the pilot has to do is push one button and away he goes.

Otherwise a pilot operated collective would be required , or an electric solenoid to induce takeoff pitch , which would require the pilot to also release the pitch after the jump is in motion , and timing would be critical.

Let me put it another way .... the beauty of Michel's system is that the pilot pushes the button for takeoff ... pitch is at maximum required ... then as lift and drag begin to slow the rotor down the governor automatically begins to reduce pitch to gyro mode .... it is an ingenious way to attain a smooth transition that is automatic and without pilot action.

I explain that poorly and I could be wrong
Interesting concept and conversations . thanks.
Martin, no I also see it differently. ;) The governor (constant speed) is NOT integral to the jump function and a collective is not the only other solution.

For example, once the button is pushed, the jump is complete, and the rotor begins to slow down and attain the 'normal' pitch, it could be LOCKED into that pitch (the usual 2-4 degrees). Once locked, there is no 'constant speed' function, yet the jump functionality is retained.
Don't misunderstand, I too think it to be a simple, yet ingenious system.
So, no collective, keep it simple. Just a way to lock the rotor into a fixed pitch, after the jump cycle.
This lock could also be simple, perhaps a pawl that allows the rotor to attain high-pitch, but upon slowing down (de-pitching), the pawl slips into a slot which locks any further movement.
Now, if it turns out that 'constant speed' does not have the issues that I mentioned, I'm all for keeping it 'as is'.
Brian
 
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