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Old May 04, 2006, 06:33 PM
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H.R. Colorado
Joined May 2006
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Quote:
Originally Posted by Tuner
FMA Co Pilot is a good basic solution.

Heading Lock gyro's should help I dont know are those GWS heading lock?

My favorite servo but a heavy one is the 59995TG. 400oz of torque titanium gears but at $130 its not cheap. If you see my design the wings are directly attached to the servo shaft. I thought for sure I would ruin these servo. Nothing yet. It seems the wing will break before the servo.

See another desing is so nice. Make me feel all warm and happy that Im not doing somthing ludacris. I will put more effort in freeing time to get programming the TH-2 for a 4 rotor tiltwing now as I am sure you can understand how complicated it can be to mix 4 motors and 4-8 servos for this.

I have worked out the mixing in my head now I just need to get it in code.
I don't think the GWS PG-03 qualifies as a "heading lock" gyro, but maybe someone else knows for sure. I've got to say, I am impressed with your design. I can't beleive those servos can handle the load placed on each wing. That may be several G's in turbulence or inadvertent aerobatic maneuvers, and even more on an imperfect landing. Can you show some pics of the servo / wing attachment? And keep us posted on the TH-2 programming...
Thanks!
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Old May 04, 2006, 08:02 PM
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United States, IN, Granger
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My gosh ,,that thing should fly in forward flight with out wings even.
I love it ,,,great job...

I had the same setup each time I flew trouble with those cheap ms gyro's on a tandem that I have and no they don't even come close to a heading hold gyro. I would think that a good Heading hold gyro would help you and probably come close to doing what you want , something like the 401 futaba or maybe the CSM 560 that is a little bit programable as far as the speed or correction and such ,but the Copilot will probably make it easier to handle . I have not worked with one yet ..so I can't help you with what it can and can't do.I have heard that there are still some limitations to where you can fly with them and also some preflight setups that have to be done and that worries me some... I guess I am going to have to part with some hard earned cash and try one some day here soon.I can't seem to get anyone to sponsor a VTOL test on one
Larry
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Old May 04, 2006, 08:13 PM
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I would also think that a setup similar to what VTOLman did ...using engine vector would work with this setup too.

I just heard from him again the other night and he has put his props on the under side of his pivot tube and says that it is even more stable now than before .It does require larger landing gear now to keep them out of the grass ,,but it is worth it for the extra stablity.

Here is a quote of what he said about it and it makes sense !!:
For the interest of anyone doing similar projects as my twin electric vtol (fixed pitch, no cyclic)
I have tested the motors pointing down below the pivoting spar tube, and the results are very good, producing a more stable hover without the slight wobble in pitch tendency.
The motors pointing up, caused the motor/prop thrust center being on the wrong side of the C of G when it tilts, causing an adverse lift.
Pointing the motors down as pushers, allows the motor/prop to move the center of thrust to the correct side of the C of G to assist lifting the FOR or AFT of the fuselage in the correct dirrection.
On the negative side.....
--- you now need a higher wing for prop ground clearance
--- the motors do not get the air flow cooling (however this is not an issue on my setup)
ALTERNATIVE is to make Z shaped spar tubes so the motors can point up, so the pivot point is above the prop.
Having said all that -- the old "motors up" set up was fine for my own personel level of heli experience, but this new "motors down" set up is definately more stable in pitch, suitable for beginners.
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Old May 05, 2006, 08:48 AM
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H.R. Colorado
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Quote:
Originally Posted by v22chap
The motors pointing up, caused the motor/prop thrust center being on the wrong side of the C of G when it tilts, causing an adverse lift.
Pointing the motors down as pushers, allows the motor/prop to move the center of thrust to the correct side of the C of G to assist lifting the FOR or AFT of the fuselage in the correct dirrection.
This is an interesting observation. So he is saying that during transition to forward flight, you want the center of pressure (thrust) behind the wing spar / pivot point? Not having done this yet, I wonder what adverse lift is generated by the props pulling instead of pushing...
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Old May 05, 2006, 09:07 AM
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Quote:
Originally Posted by v22chap
My gosh ,,that thing should fly in forward flight with out wings even.
I love it ,,,great job...
Larry
Thanks for the kudos. I know that with this much thrust available I don't have to worry too much about aerodynamic lift, but for real world purposes, I wanted to be able to land this thing completely power off. That could get ugly though. Maybe I can figure out how to autorotate
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Old May 05, 2006, 10:21 AM
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With the props pulling above and forward of the CG ,,, it actually pulls the nose up ,,and you have to counter with some nose down.
I suspect that with the props pushing from under and behind the cg you would actually do away with the nose up and actually get a little nose down.Maybe he is following this and will chime in on what actually happens.
Larry
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Old May 05, 2006, 11:51 AM
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Ahhhh...yes I guess that would happen for a twin rotor. For a 4 rotor, the fuselage should remain parallel to the ground if thrust amount and vector remains equal on all 4 rotors.
Actually, one of my design goals was to allow the pilot to input nose up and nose down attitude through the elevator stick in horizontal mode. But during transition, I want the on-board stabilization system to limit that attitude to a comfortable angle. It seems that a fast climb would be easier and faster in a reduced-drag, horizontal (airplane) mode. Having some nose-up attitude could also allow some lift to be generated by the fuselage, and part of my wing is fixed to the fuselage.

But I'm getting ahead of myself...thanks for the clarification.
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Old Jun 14, 2006, 10:58 PM
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San Carlos, California, United States
Joined May 2002
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Quote:
Originally Posted by Unconventional
I don't think the GWS PG-03 qualifies as a "heading lock" gyro, but maybe someone else knows for sure. I've got to say, I am impressed with your design. I can't beleive those servos can handle the load placed on each wing. That may be several G's in turbulence or inadvertent aerobatic maneuvers, and even more on an imperfect landing. Can you show some pics of the servo / wing attachment? And keep us posted on the TH-2 programming...
Thanks!
The GWS PG-03 is not a heading hold (heading lock) gyro.

Heading hold gyros have drift and will not work well for stabilizing a VTOL pitch or roll. It will slowly drift and the VTOL will flip over.

Toshi
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Old Jun 14, 2006, 10:59 PM
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San Carlos, California, United States
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Quote:
Originally Posted by Unconventional
Here is an updated diagram. The gyros were changed since that old diagram was made and there is no more Vtail mixer. That experiment did not work at all.
Jim
You can probably eliminate one of the roll gyros by using a Y-lead?

Toshi
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