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Old Apr 07, 2009, 04:31 PM
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Trex450: Inverse Tail Rotor Direction????


i own a trex450, that i still learn to fly these days.

i noticed that the tail-rotor-bushing is way off-center when hovering.
(the heli is assembled according to the manual: top of the tail rotor rotates away from the main rotor).

when the bushing is centered, the blades have a AOA of about 10deg. but it's in the wrong direction for hovering. this means the the servo has to move the bushing to the left, for stable hovering (gyro in normal mode)

i gave it a try and invertet the twist of the belt and the tail blades.

now the pitch bushing is about cented when hovering. i didn't do much flight tests today, just small hovering tests in the kitchen!

here is my question:
why is the trex design asymetrical???? shouldn't be there the same travel left and right for the tail-rotor-bushing??? or do i just had bad luck with single part tolerances???

With the stock setup, the heli hovered nice, but i had to reduce the travel completely to 60% with the limiter at the gy401. this means only 60% of servo travel --> nooo good for precision, right????

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Old Apr 08, 2009, 01:05 AM
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Why is the trex design asymmetric? Because more right rudder is required than left. Right rudder has to overcome main rotor torque, left rudder is assisted by main rotor torque!
I think you have the tail rotor blade grips backwards. The blade grip horn should be on the leading edge side of the blade. I have seen this before.
Old Apr 08, 2009, 10:50 AM
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Originally Posted by 172AMD
Why is the trex design asymmetric?

Stock assembly:
when hovering, the tail rotor bushing is NOT centered (not even close)
this means different travel left and right from hovering point!!
(limiter needs to be closed to 60% travel at the gyro)

my assembly:
when hovering the tail rotor bushing is pretty mutch centered. this means equal travel left and right from the hovering point!!
(limiter at 100%)

i just did a small hover test. the tail rotor bushing is centered, and the heli hovers stable, the tail works about perfekt.....

but why is my trex different from million others???
Old Apr 08, 2009, 08:23 PM
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If your limit is too low, move the ball link out one hole on the servo horn. If it's not broke, don't fix it. The gyro controls your piro rate and keeps them consistent, it's not so much an issue of mechanical ability.

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