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Violent dive on rudder right - Fly Baby - 9/12/2012 6:10 PM   
Winrich


 

Posts: 25
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From: Augsburg, GERMANY
Status: offline 		Hi guys,

We are running out of ideas how to correct some very strange behavior of a 1.20 size Fly Baby ARF. When applying right rudder (without any aileron input), the plane has not the slightest tendency to turn right but immediatiatly goes into a dive. The more rudder the more violent the dive. The response to rudder left is reasonably well although the plane needs some more than typical elevator to compensate for a notworthy dive tendency. This behavior is more or less the same at any throttle position. The CG is according to plan. We checked that there is no mixer active. There is no unreasonable slop in the rudder train and a powerful rudder servo is installed.

Any suggestions what's wrong?

Thank you and best regards

Winrich

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RE: Violent dive on rudder right - Fly Baby - 9/12/2012 8:12 PM   
opjose



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From: Poolesville, MD, USA
Status: offline 		This sounds like torque induced gyroscopic precession to me.

Try flying the plane up to full throttle and as it is flying level throttle it back to idle then see how it responds to rudder inputs with the engine at idle.



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RE: Violent dive on rudder right - Fly Baby - 9/12/2012 8:51 PM   
rmh



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From: , UT, USA
Status: offline
quote:

ORIGINAL: Winrich

Hi guys,

We are running out of ideas how to correct some very strange behavior of a 1.20 size Fly Baby ARF. When applying right rudder (without any aileron input), the plane has not the slightest tendency to turn right but immediatiatly goes into a dive. The more rudder the more violent the dive. The response to rudder left is reasonably well although the plane needs some more than typical elevator to compensate for a notworthy dive tendency. This behavior is more or less the same at any throttle position. The CG is according to plan. We checked that there is no mixer active. There is no unreasonable slop in the rudder train and a powerful rudder servo is installed.

Any suggestions what's wrong?

Thank you and best regards

Winrich

Sounds like basic trim is not correct - for example left trim is countering aileron setup
which produces aright turn
and /or it is quite nose heavy.

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RE: Violent dive on rudder right - Fly Baby - 9/22/2012 1:37 AM   
mithrandir



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From: adelanto, CA, USA
Status: offline 		Right rudder causes a dive??

Is the elevator control horn on the left side? check the stiffness of the elevators... is the right one floppy?

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RE: Violent dive on rudder right - Fly Baby - 9/22/2012 2:00 PM   
RCPAUL


 

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Joined: 12/15/2001
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From: Gahanna, OH, USA
Status: offline 		HOW MUCH DIHEDRAL?

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RE: Violent dive on rudder right - Fly Baby - 9/24/2012 9:07 PM   
BMatthews



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From: Chilliwack, BC, CANADA
Status: offline 		As you're seeing there is simply no aerodynamics reason for this to occur. It's far more likely that you've got some sort of bad wing warp or the wing on one side is shaped differently from the other or there is some other side to side nonsymetry issue at work. So the first step would be to measure out all the wing to fuselage alignment factors. Then check for warps and at the same time ensure that the wing is shaped and balanced symetrically from side to side.

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