Interesting, so speed trim system introduces dynamic instability. As rotor pitches back it causes that head to dig in, with divergent phugoid. I imagine front rotor causes most of the effect, hence cured by the sharp cyclic input before hitting the shear.
Maybe an airspeed sensor was not enough, and there should be a gyro to provide longitudinal damping in the system too. Terninology check LCT stands for Longitudinal Cyclic Trim, but not sure what ADC stands for...
Mart
Last edited by Graviman; 10th March 2007 at 10:54.