2X shake

Still, has some difficulties,hope you can help me.
Is the main Rotor used to turn the gyrocoptrt(tilting) or it's only there to define height of the gyrocopter?

Tilting the rotor also helps turn the gyroplane.

This brings up another interesting aspect regarding the height spacing of the the teeter axis from the control axes, particularly the lower roll axis. While tilting the rotor aids in turning the gyroplane, offsetting the rotor head to the inside of the turn as it is tilted, counteracts tilt and rudder input by moving the center of lift toward the inside of the turn.

This might be another good reason to have all three axes on the same plane.
 
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Thank you Alan,

I didn’t read your response well and imagined incorrectly you had changed the ratio of the control system. I see that if the only thing you did was raise the rotor head with a spacer than the control system ratios would remain constant.

I stand corrected.

Where do you feel the extra force goes?

Thank you, Vance
 
Graham Rotor Head

Graham Rotor Head

Here's what I'm talkin' about.
 

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Hi Terry.
You've made me curious, Does this type of rotorhead eliminate under sling? If so, doesn't under sling help balance center of mass changes when one blade is higher in the plane of rotation than the other. Or have I got things wrong again?
 
Hi Terry.
You've made me curious, Does this type of rotorhead eliminate under sling? If so, doesn't under sling help balance center of mass changes when one blade is higher in the plane of rotation than the other. Or have I got things wrong again?[/

Dennis, you are correct, but the necessary undersling can still be achieved.
One interesting example of this type rotor head is the one built by Dick DeGraw for his wife's gyro, "DeBird" I think he calls it. He went this route in order to facilitate some other features like continous partial power and jump takeoff. All design involves trade-off, and there are always some "down-sides", or negatives. In rotor heads of this type stability can be a problem. "Neutral" trim centering and control sense feed-back must be artificialy augmented. Absents of control pressure graduant may sound good on paper, but it is very unpleasant to fly. Without a very stable airframe, it is suicide!:sad:

Back in the 60's Jerrie Barnett designed and built a simular arrangement for the JB-4. He coupled the prerotator drive universal directly to the spindle. After a bit of experimental experience, he realized the positive stability advantages of the offset and moved the pitch axis forward of the spindle. Eventualy he went full-circle back to his earlier-later "offset yoke" design with a few revisions. :yo:
 
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Hi Terry.
You've made me curious, Does this type of rotorhead eliminate under sling? If so, doesn't under sling help balance center of mass changes when one blade is higher in the plane of rotation than the other. Or have I got things wrong again?

Hi Dennis,

My idea is not to eliminate rotor undersling.

Undersling is necessary, but, to my understanding, it is the teeter hinge itself which is balancing center of mass when one blade is higher than the other, while it is undersling which aligns center of mass in flight with the teeter hinge. I know this sounds like nit-picking, yet there is a distinction.
 
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You might notice I did not include the spindle location in my nomenclature for the head.

Spindle offset might still be needed to be used for stability as 'passing' points out; and it is tertiary to rotational stability.

I do not think anyone else has combined these design components in the manner I describe. But if they have, it would be interesting to see.

3:33pm Edited revision to the above: My dog pays a lot of attention to these things, and he said I confused him. I am a little vague here, so I will keep working on my nomenclature to make it clearer. I've been on some powerful antibiotics for the past few weeks due to an injury sustained on my scooter. Sometimes forget to dot my 'T's and cross my 'I's.
 

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A little more research

A little more research

Not knowing much about gyroplanes, never having actually owned, built or flown one; I thought it appropriate to do some more research on past rotor head discussions and found a couple iterations of Barnett's.

DeGraw's Gyrhino is somewhat of a hybrid using cyclic control, flying somewhere between helicopter and gyroplane.

None appear to broach the idea of having the teeter, pitch and roll pivots pass through a common central point.
 

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Terry, NONE of the photos yo show are Karrol DeGraw's "DeBird"!

The "Gyrino" is Dick's original jump takeoff machine he built about 20 years ago.
If you look past the drive and the "wooblin' rod" cyclic / collective, up there in the black short cylinder you'll find what you're talking about. At least as best I can interpet what you are talking about.

I don't know what the red machine is, except it is just another way of increasing the undersling without raising the head. I've used that method in a couple of my experiments.
 
Terry, NONE of the photos yo show are Karrol DeGraw's "DeBird"!

The "Gyrino" is Dick's original jump takeoff machine he built about 20 years ago.
If you look past the drive and the "wooblin' rod" cyclic / collective, up there in the black short cylinder you'll find what you're talking about. At least as best I can interpet what you are talking about.

I don't know what the red machine is, except it is just another way of increasing the undersling without raising the head. I've used that method in a couple of my experiments.

My bad. I found those pictures in posts mentioning the DeBird and Barnett's designs. Supposedly, the middle picture is Barnett's attempt at direct prerotation, which you mentioned. The red one appeared to be Barnett's as well, assuming from the post it was from, but it has the pitch and roll axes on the same plane while the teeter is elevated.

Though I got the wrong image, couldn't find a good DeBird image, the DeBird also had a cyclic control head like the Gyrhino, but without collective.

I do not think the dynamics of a flap hinged cyclic control rotor head would be a valid comparison to a teetering gimbal head, particularly if partially powered in flight. If you know a reason it would, it would be interesting to ponder.

Thanks for pointing those things out.

Learning here.
 
I basically have gone through the same thoughts as you Terry….and semi-ended up with a semi-rigid head, which has its own problems. It did fix the pre-rotation "control-torque" problem though. I always came back to my rigid-head because it "fixed" the stuff I didn't like and most of what you're talking about….although it does add some of its own peculiarities….like a swashplate and servo-tabs, but these I can live with. If you want simple, go with the standard run-of-the-mill teetering head.....and learn to live with it ;).
 
Terry, here is a video you may or may not have seen.
The first gyro visible is the "Gyrino"; the second one that looks somewhat like a 2-place Dominator is Karrol DeGraw in "DeBird".
It ain't what you're looking for, but I thought it may interest you.
http://www.youtube.com/watch?v=9gfBYARn-T8

It is interesting, and I had viewed them before.

For me, as much as I enjoy following helicopter happenings here on the forum, sharing in the fun Stan and others are experiencing; helicopters and gyros are two entirely different animals; and I am just not that interested in helicopters or helicoptering hybrids from a flying standpoint. Design and engineering are another thing.

If I am going to fly, it will be a gyroplane.

I have an overactive imagination, and whether I ever fly or not, I'll have contributed to the conversation, obnoxious or not.

Right now I have an all plywood ultralight gyroplane with two inexpensive, aircooled, 20hp lawnmower engines driving counter-rotating handmade props in mind. All lumber/hardware store stuff if one adds Benson blades. Could build it for a couple Gs using stitch and glue technique. Or an aluminum V-8, tractor powered gyro with a four legged rotor tower over it and continuing down to landing gear, with the pilot saddled behind the tower and engine.

Another concept would be, instead of dart-like tail feathers on a gyroplane, a set of split vanes set out from and running down either side of the mast with separate control of each vane for pitch and roll effect.
 
I basically have gone through the same thoughts as you Terry….and semi-ended up with a semi-rigid head, which has its own problems. It did fix the pre-rotation "control-torque" problem though. I always came back to my rigid-head because it "fixed" the stuff I didn't like and most of what you're talking about….although it does add some of its own peculiarities….like a swashplate and servo-tabs, but these I can live with. If you want simple, go with the standard run-of-the-mill teetering head.....and learn to live with it ;).

Hi Ed,

I am still proposing a teeter head for simplicity, but suggesting that it might be better if the teeter, roll and pitch axes are at the same elevation. It does not look as though anyone has tried this arrangement.
 
The Bell H-13 and I believe the Hiller have those axis on the same gimbal plane...the "problem" is that the shaft/mast must have enough clearances from this head hole for antiquate teeter in all axis. The head must therefore be larger and stronger due to that center hole. Sigh....I know....clear as mud.
 
The Bell H-13 and I believe the Hiller have those axis on the same gimbal plane...the "problem" is that the shaft/mast must have enough clearances from this head hole for antiquate teeter in all axis. The head must therefore be larger and stronger due to that center hole. Sigh....I know....clear as mud.

I understand , I think.

I agree with you and all others about the difficulties of design; making room for stuff. But I already have several ideas to accomplish it.

I try to ignore helicopter rotor systems in my deliberations for their inherent differences. An entirely different animal than the simple gimbaled teeter gyroplane.
 
Here’s a rotorhead with coincident teeter hinge and roll/pitch pivots using a Shafer A-8 spherical roller bearing.

Its only usefulness was as a learning tool. It taught me the essential roll played by rotor thrust feedback in making unstable gyros flyable.
 

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Here’s a rotorhead with coincident teeter hinge and roll/pitch pivots using a Shafer A-8 spherical roller bearing.

Its only usefulness was as a learning tool. It taught me the essential roll played by rotor thrust feedback in making unstable gyros flyable.

Thanks Chuck. I really appreciate you chiming in.

Pete had suggested the same thing earlier. But it appears you have actually tried this.

Do you have any pictures of the gyro with this rotorhead? It appears your design did not have an offset spindle.

I am always wanting to understand things, and it is sad for me to know that someone else has already tried a similar thing; so I hope you do not mind a little badgering.

Quantifying rotor thrust feedback, in your opinion, is it important to have feedback from the teeter, from the roll axis, from the pitch axis, from spindle offset, or from some pair, triple or all of them?

It appears that some helicopters get by without roll and pitch or offset spindle feedback. Is it because the dynamics are different when the rotor is propelling the craft; and/or that they too are somewhat no fun to autogyro?

What if direct control and a self-centering, sprung roll and pitch trim were delivered to an A-8 on the lower end of the spindle such that the spindle would always seek neutral position? This in place of roll and pitch feedback from the rotorhead stack? Had you tried something like this?

And another idea: what if the rotor spindle were also sprung and dampened in line with its rotational axis so that the spindle shaft would ride up and down through the upper A-8?

Or, am I trying to spoil all the fun?

I have never owned, built or flown a gyroplane, but I hope to one day.
 
It appears that some helicopters get by without roll and pitch or offset spindle feedback.

All helicopters I'm aware of get by without any, control forces on a collective pitch ship would get out of hand without a swashplate type control setup - that's also one reason they're harder to fly than gyros.
 
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