Tail swing Trex 450

[cilliers]

I am experiencing some difficulty in determining the cause of a newly acquired tail swing with my Trex 450. I am using a Futaba GY240 Gyro and once gain is setup to above +75% I experience the expected tail wags (hunts) and after a while hovering the tail may swing 30 to 90 degrees. If gain is set lower the tail still wag somewhat but slower and after about 3 or 4 wags it swing around abruptly by 30 to 90 degrees. I have changed gyro, motor, ESC, crystals, receiver, main shaft, checked all gears for missing teeth, slip – everything normally associated with above problem – no change. Did anybody experience the same problem before, any suggestions?

[Old man]

Check the tail gear drive some times the gear slips on the axel it happen 2 times to me so i had to upgrate on cnc tail drive gear.

[cilliers]

This was the first item I checked and rechecked - definitely no slip.

[Smith]

I am having the same problem but when I go from hover to increased power to go vertical? I have no slippage. Could it be in the transmitter settings DX6?

[hawkman]

Check the linkage from servo to the tail pitch slider....if the links on the ball ends are tight then you will get a rebound effect...make sure you can easily rotate the links on the balls....use a ball link resizer...you can make one using a spare ball link....score it across the ways using a craft knife...be very careful not to slip and injure yourself...then pop this into the link...rotate back and forward...but dont go too mad...remove and pop the linkage back on to the ball link...the linkage should be able to rotate easily...using finger tips...you dont want it too loose...but you dont want it tight either.

Rob

[cilliers]

Hi guys,

Thanks for the help. I actually posted a reply quite some time ago - for some reason I don’t see it but I did manage find the problem. The tail rotor grip was binding under power because of a faulty bearing in the grip. This only happened under power when the centrifugal forces pressed the grip tightly against the bearing. As a result the gyro were over compensating as a small signal for change in tail pitch were not able to immediately change the pitch and thus the direction of the heli and these errors were magnified in every signal till total loss of control.

[hawkman]

Good point....thats something to think about if someone else experiences the same problem.

Rob