02/11/2014: The operational flexibility of a tiltrotar is clearly seen when the Marines approach landing sites. The ability to maneuver through the battlespace to shape alternative pathways to an LZ is important. The ability to get away rapidly in transition from rotor to plane mode is also a key capability.
The flexibility generated by the nacelles is a key facilitator of the Osprey’s capability.
The process of rotating the nacelles between helicopter and airplane mode is called “transition”, and the reverse from airplane mode to helicopter mode, “conversion”.
Transition and conversion procedures are simple, straightforward, and easy to accomplish.
The amount and rate of nacelle tilt can be manually controlled by the pilot or can be performed automatically by the flight control system.
The V-22 can perform a complete transition from helicopter mode to airplane mode in as little as 16 seconds. Conversions and transitions can be continuous, stopped partway through, or reversed as desired.
A tiltrotor can fly at any degree of nacelle tilt within the authorized conversion corridor envelope.
During vertical takeoff, the conventional helicopter controls are utilized. As the tiltrotor gains forward speed, the wing begins to produce lift and the ailerons, elevators, and rudders become more effective.
Between 40 and 80 knots, the rotary-wing controls begin to be phased out by the flight control system. Once in airplane mode, the wing is fully-effective and pilot control of cyclic pitch of the proprotors is locked out. Because the nacelle angle can be commanded separately from the primary pitch controls of rotor cyclic and tail elevator, the conversion corridor (the range of permissible airspeeds for each angle of nacelle tilt) is very wide (about 100 knots).
In both accelerating and decelerating flight, this wide corridor means that a tiltrotor can have a safe and comfortable transition or conversion, offering the combined advantages of speed and maneuverability for low level flight.
During a visit of the Second Line of Defense team to New River Air Station in North Carolina on February 10, 2014, the team experienced during a USMC training session the ability of the Osprey to land and depart LZs rapidly and the transition and get away speed of the airplane mode.
This flexibility is a core combat capability provided to enable the Marines getting off and getting back onto the plane enhanced security and effectiveness.
Not always easy on the stomach, and it would be better to be in the front of the aircraft, when such flexibility is demonstrated, but the Osprey is clearly not a helicopter when it comes to the LZ.
Credit Photos: Second Line of Defense