I am confused with the tail set up. I heard that I could not use Futaba 9ZHW digital trim once the heading hold gyro was initially setup on the bench. Few weeks ago I did not have any problems and on the recent flight, my Xcell is keep slightly turning left.

-- Anton Matusevich (matusev@earthlink.net), January 20, 2000

Answers

Thats how I do it, Anton. Setup a tail linkage, initial tail rotor pitch and gyro according to the manual. Reset rudder digital trim to 0 (neutral). Then I lift my Xcell in hover, transmitter gyro switch set to NORMAL mode. If machine is turning left or right I land the helicopter and adjust the length of the tail push rod until my heli is trimmed. (If heli is turning left make a push rod shorter, - if heli is turning right make a push rod longer). At this point the rudder is trimmed in gyros normal mode. Now turn the gyro switch in heading hold mode. I usually assign the switch F in my Futaba-9ZHW for a gyro mode. Give the full left/right rudder command and watch the rudders servo arm  it should stay still if the rudder is in trim if not  now is the time to use digital trim on the radio. Lift machine in hover and using digital trim on the radio make sure machine is holding the course. If it seems that it is not possible to trim the rudder exactly you can try to reset the parameters of the digital trim for the rudder to make it more fine  higher resolution: parameter First Step Rate. Futabas default is 3. I am usually resetting to 1 for the rudder channel. TRM function. To sum it up: In Normal gyro mode always trim the rudder mechanically, in heading hold mode use a transmitters digital trim. I'll see you on the field.

-- Jack G. (webmaster@heliweb.com), January 23, 2000.