Cliff & Carol McKeithan 
Flew the Mohawk in Vietnam, flew choppers, and was Deputy Program Manager for Military Applications for the XV-15.
The XV-15 led to the V-22 Osprey. Just recently, the Army selected Bell’s V-280 tilt rotor aircraft to replace the Blackhawk. I did fly the XV-15. It was amazingly easy.
The. XV-15 was inherently stable and the controls were identical to most helicopters with the exception of the tilt switch It was positioned on the collective lever such that the pilot’s thumb could naturally fall upon it without searching. The conversion corridor was sufficiently wide, making it easy to remain in the center by keeping the pitch attitude level. Using the collective for power (airspeed) in airplane mode felt natural. Coming back to helicopter mode was a matter of keeping pitch attitude level at whatever the nacelle angle was, resulting in the aircraft being in the center of the conversion corridor. Transitioning a helicopter pilot into a tilt rotor aircraft would be easy. A fixed wing pilot would require additional training in hover operations.
One of many proposed aircraft using tilting propulsion systems. The success of the XV-15 and the V-22 Osprey has inspired developers to design aircraft bridging the gap between helicopters and airplanes.
For What They Gave on Saturday Afternoon 