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Old Oct 28, 2010, 06:15 AM
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Originally Posted by Brandano View Post
differential tilt between front and rear motors. Trade some of the forward thrust of the front motors for up thrust. Essentially, mix the tilt of the rear motor with elevator, so that the mix is at 0 in VTOL mode and 100% in forward flight
Good idea except that the rear motor on this bird doesn't tilt. I get a lot fewer vibration problems with having the rear motor fixed. The quad version had a similar idea but the vibs resulted in a nice "death rattle" resonance, seen in the video below, which is now gone.

QTD_FirstCodeTest.AVI (0 min 39 sec)
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Old Oct 28, 2010, 07:23 AM
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Hmm, then same thing but with the front motor tilt set in an elevon mix. In vertical mode pitch and roll are controlled by motor rpm, and yaw by tilting sideways the rear motor. In forward flight roll is controlled by differential tilt and pitch by coordinated tilt, decreasing the mix with motor rpm. Essentially, as you reduce RPM on the rear motor so should decrease the pitch mix with the speed controllers and increase the pitch mix with motor tilt. In vertical flight differential tilt could control yaw, allowing you to leave the rear motor fixed and saving the weight of a servo. However this means a much more complex mix that could turn out hard to implement
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Old Oct 28, 2010, 07:46 AM
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Originally Posted by RCvertt View Post
Good idea except that the rear motor on this bird doesn't tilt. I get a lot fewer vibration problems with having the rear motor fixed. The quad version had a similar idea but the vibs resulted in a nice "death rattle" resonance, seen in the video below, which is now gone.
I have seen this Servo Jitter before. What I did to resolve it is to add some delay on my gyros. I am not sure as to how you are driving your tilting servos, but if there is a way to slow them down, that will help or you can always use faster servos.
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Old Oct 28, 2010, 08:32 AM
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The delay and slow down of the gyro is what is needed .. Vtol man did a lot research on this and he found that older rate gyros worked better as they didn't return to nuetrual position so quick ... and that is what a tail rotor gyro is designed to do .. look for Futabas gyros used on airplane they are designed for slowe action in the control system
351 or 352 if you can find them any more ... Do a search for my explaination of this with a video and all .... don't have time right now myself to look it up ,,got to go to a meeting
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Old Oct 29, 2010, 10:07 AM
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Quote:
Originally Posted by Brandano View Post
Hmm, then same thing but with the front motor tilt set in an elevon mix. In vertical mode pitch and roll are controlled by motor rpm, and yaw by tilting sideways the rear motor. In forward flight roll is controlled by differential tilt and pitch by coordinated tilt, decreasing the mix with motor rpm. Essentially, as you reduce RPM on the rear motor so should decrease the pitch mix with the speed controllers and increase the pitch mix with motor tilt. In vertical flight differential tilt could control yaw, allowing you to leave the rear motor fixed and saving the weight of a servo. However this means a much more complex mix that could turn out hard to implement
Sounds good. Looks like controlling roll and yaw when at 45 degrees tilt will be tricky. Differential thrust will roll the craft in one direction and yaw it in the other direction at the same time.

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Originally Posted by reverendrichie View Post
I have seen this Servo Jitter before. What I did to resolve it is to add some delay on my gyros. I am not sure as to how you are driving your tilting servos, but if there is a way to slow them down, that will help or you can always use faster servos.
Interesting. That's one of the cool things about the AeroQuads arduino, we can basically make things move as fast or as slow as we need.

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Originally Posted by v22chap View Post
The delay and slow down of the gyro is what is needed .. Vtol man did a lot research on this and he found that older rate gyros worked better as they didn't return to nuetrual position so quick ... and that is what a tail rotor gyro is designed to do .. look for Futabas gyros used on airplane they are designed for slowe action in the control system
351 or 352 if you can find them any more ... Do a search for my explaination of this with a video and all .... don't have time right now myself to look it up ,,got to go to a meeting
Thanks for the info. I'll search for your videos, had them book marked at one point, and see if I can slow mine down. We have a gyro filtering option that maybe I just need to crank up a little.
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Old Nov 27, 2010, 08:53 PM
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This is just about the only design that can hover and still be very efficient at forward flight.. Its my opinion this will soon be the standard for VTOLs with long range missions.!!

Eddie Weeks
http://www.jetlens.com
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Old Mar 21, 2011, 01:14 AM
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This is just about the only design that can hover and still be very efficient at forward flight.. Its my opinion this will soon be the standard for VTOLs with long range missions.!!

Eddie Weeks
http://www.jetlens.com
I agree. Looks like the dual prop versions are going to catch up fairly soon but I think the quad and tri version will handle wind better and be able to carry more weight until we see another major advancement in motor or battery technology.

The tri version is ready for forward flight testing/crashing now. Decided to throw a quad version together before I do that since it takes an hour to get to the flying field.


Tri maiden hover...
TDD FlyingWingTricopterVTOL (0 min 41 sec)


Quad motors and retract...
Xvtol-MotorTiltTest.AVI (0 min 40 sec)
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Old Mar 21, 2011, 05:42 AM
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looking good ... hope you get a chance to do forward soon
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Old Mar 21, 2011, 05:55 AM
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Looks good and very inspiring.
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Old Mar 21, 2011, 08:10 AM
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Nice work! It looks like it should work fine for the transition. Good luck.
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Old Mar 21, 2011, 10:41 AM
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Very cool, subscribed!
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Old Mar 22, 2011, 11:14 PM
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I was so impressed with this idea, I built one... and it works well...

Forward flight, then hover... no problem

Eddie

ArduPilot Mega, custom code, Tri-Coppter (1 min 42 sec)
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Old Mar 23, 2011, 02:31 AM
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Thanks for the nice words all. Hope to get up soon V22, fingers crossed.
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I was so impressed with this idea, I built one... and it works well...
Now if only I can get mine to hover as nicely.
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Old Mar 23, 2011, 08:08 AM
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Originally Posted by EddieWeeks View Post
I was so impressed with this idea, I built one... and it works well...

Forward flight, then hover... no problem

Eddie

http://www.youtube.com/watch?v=wpPiSTGLLf4

Very Nice Eddie, very inspiring!
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Old Mar 23, 2011, 08:42 AM
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Nice work Gents! Added to the Quadrocopter and Tricopter Mega Link Index under a new index Project hybrid multicopter plus fixed wing builds:
@EddieWeeks
Do you have a build log that I can reference? Do you have any forward flight and transition video posted yet?
Cheers,
Jim
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