Lu
Your post about the AH-46 Cheyenne, and more significantly the postings on gyroscopic precession raises an interesting thought.
Dynamic stability of helicopters is an ongoing design consideration.
We also know that some aircraft instruments maintain an orientation in space by the use of two gyroscopes that rotate in opposite directions, on a common axis. The requirement for two counter-rotating gyroscopes is to cancel the 90-degree precession, of course.
Since helicopter rotors exhibit some gyroscopic precession, it would appear that coaxial helicopters, and to a lesser degree intermeshing helicopters, have a 'built in' damper on pitch and roll oscillations, which single rotor helicopters do not have.
[ 07 September 2001: Message edited by: Dave Jackson ]