Originally Posted by
wrench1
the same "vertical hop" and tail wag are possible with Bell blades as well..
It is my understanding that the “vertical hop” with Van Horn blades is asynchronous with main rotor 1/rev which makes it completely different from the “hop” with Bell blades. With Bell blades the “hop” at certain torque settings (ground and flight) is at 1/rev and is aggravated by a swashplate with freeplay when the sum of the forces on the swashplate oscillates through zero. With Bell blades this “feature” is never at a level that would be considered violent. The VH “hop” sounds more like it is sourced from a rotor mode coincident with an airframe/pylon mode.