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Hi
I see quite a lot of messages from people having problems with th etal of thier helis, which has prompted me to put this one up on the forum as a warning to others.
I was messing around with my "test heli", a Belt CP with loads of mods all over it yesterday, and one of the things it has is a real mongrel of a tail gearbox and rotors system. It has this tail system for quite some time, and has behaved fine, and the only change I had made recently was to put on some different shaped tail rotor blades.
I was testing it out in the hover, and the tail just would not behave itself no matter what I trid to do. I did all the normal stuff, adjusting the servo position, checking the horn for being perpendicular, adjusting th gain up and down, but it still jumped from side to side and was virtually unflyable.
In desperation, I stuck it up on the turntable in my hanger again, but decided to lock the turntable so I could watch the tail movement more closely.
It didn't take too long for me to spot the problem doing it this way....
I spotted that the tail shaft was moving in an out with the control yoke about 1/2 a mm, but only when it approached the maximum travel points each way.
I stripped it down, and found a little washer that was the correct internal diameter for the shaft, and also correct to rest against the inner bearing sectin only of the main bearing.
Reassembled it again, and checked for movement and binding. All I needed to do was not pull those end three screws up rock solid, as I usually do, and the tail assembly turned nice and smoothly.
I rest the servo position on the turntable, again.... and then took her back out to fly her - PERFECT.
So, the moral here is to always check for end float on your tail drive shaft, as the smallest amount of movement really can cause you to have an almost uncontrollable heli rudder system.
Obviously what was happening is that when the tail moved, the gyro responded, th etail shaft moved, the gyro responded to that, on and on, which made totale sense of all the wagging and changes in direction I was seeing before.
Hopefully this may help others to avoid this litle trap
I see quite a lot of messages from people having problems with th etal of thier helis, which has prompted me to put this one up on the forum as a warning to others.
I was messing around with my "test heli", a Belt CP with loads of mods all over it yesterday, and one of the things it has is a real mongrel of a tail gearbox and rotors system. It has this tail system for quite some time, and has behaved fine, and the only change I had made recently was to put on some different shaped tail rotor blades.
I was testing it out in the hover, and the tail just would not behave itself no matter what I trid to do. I did all the normal stuff, adjusting the servo position, checking the horn for being perpendicular, adjusting th gain up and down, but it still jumped from side to side and was virtually unflyable.
In desperation, I stuck it up on the turntable in my hanger again, but decided to lock the turntable so I could watch the tail movement more closely.
It didn't take too long for me to spot the problem doing it this way....
I spotted that the tail shaft was moving in an out with the control yoke about 1/2 a mm, but only when it approached the maximum travel points each way.
I stripped it down, and found a little washer that was the correct internal diameter for the shaft, and also correct to rest against the inner bearing sectin only of the main bearing.
Reassembled it again, and checked for movement and binding. All I needed to do was not pull those end three screws up rock solid, as I usually do, and the tail assembly turned nice and smoothly.
I rest the servo position on the turntable, again.... and then took her back out to fly her - PERFECT.
So, the moral here is to always check for end float on your tail drive shaft, as the smallest amount of movement really can cause you to have an almost uncontrollable heli rudder system.
Obviously what was happening is that when the tail moved, the gyro responded, th etail shaft moved, the gyro responded to that, on and on, which made totale sense of all the wagging and changes in direction I was seeing before.
Hopefully this may help others to avoid this litle trap
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