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Old 07-09-2011, 03:40 AM
  #6  
Larry3215
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Join Date: Mar 2006
Location: Gig Harbor, Wa USA
Posts: 7,061
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Thats not something Ive run across before.

My first suspicions are either a warped wing or an unwanted control mix in the tx..... or in your hands

First - do a couple of tests on the ground.

1)Look very carefully at each wing half and see if they have the same amount of twist or no twist as the wing goes out from the center to the tip. You can block the model up level front to back and set each wing tip trailing edge at the tips the same height from the table. Then carefully measure several places along the trailing edge and leading edge down to the table surface. Each wing half should have very close to the same measurements.

For the next tests its safest to remove the prop

2)With the model on the bench, move ONLY the rudder stick left and right while you watch the elevator very carefully. Does it move at all? Do the ailerons move at all?

2A)This next test is difficult to do (honestly) for most people. Try the same test again but holding the tx like you normally do in flight and imagine your making a left turn and then a right turn. Watch the elevator again and see if your adding some elevator input without realizing it.

3)Remember we needed the prop removed? Bet you didnt do it before Do it now for sure!

Run the throttle up to about 1/2, then give the model left rudder then right rudder. Did the motor speed change? If so, you are probably doing that even more in flight. That could cause significant speed changes. if your motor thrust line is off (up or down) that could cause your problem.

What does the plane do when you abruptly give it full throttle in flight from say 1/4 or 1/2? What does it do when you cut the throttle abruptly from full to zero? Any tendency to dive or climb with throttle changes? If so, you may be adding throttle when you turn left and reducing throttle when you turn right (or the reverse depending on how you hold your tx). That would then cause a dive or climb depending on which way things are off.

I would check for warps first and fix any you find. Then do the above tests and correct as necessary.

Then go back and do Ed's "trimming" thing above in the first post.

When thats pretty close, then go to my post #2 above and do the steps in the first link.

By the time your finished with all that the plane will be flying great
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