The V-22 Osprey is a medium lift, multi-mission, vertical/short takeoff and landing (V/STOL), tilt-rotor aircraft developed by Bell Helicopter Textron and Boeing to fill joint service combat operational requirements for the year 2001 and beyond.
The V-22 operates as a helicopter when taking off and landing vertically. The nacelles rotate 90 degrees forward once airborne, converting the Osprey into a turboprop aircraft. It can provide V/STOL with a payload of 24 troops, or 6,000 pounds (2,722kg) of cargo, at 430 nautical miles (796km) combat range, or V/STOL with a payload of 8,300 pounds (3,765kg) of cargo for a range of 220 nautical miles (407km). The tilt-rotor aircraft is self-deployable world wide with a ferry range over 2,100 nautical miles (3,889km).
This very unique aircraft is available in three configurations for U.S. Joint Services Operational Requirements: the CV-22 for long-range special operations missions for the USAF’s Special Operations Command, the MV-22 for combat assault and assault support for the U.S. Marine Corps, and the HV-22 for combat search and rescue, special warfare, and fleet logistic support. (Sea trials of the MV-22 have taken place and will be followed by Operation/Evaluation from September 1999 to May 2000.)
Boeing V-22 Osprey History
Bell XV-15 Tilt-Rotor
The XV-15 Tilt-Rotor testbed aircraft was designed by Bell Aircraft in the mid-1970s under a contract with NASA and the U.S. Army. It was capable of taking off and landing vertically like a helicopter and of flying horizontally when its “proprotors” were rotated forward and downward. NASA’s Ames Research Center, Mountain View, CA, and the Army’s Air Mobility Laboratory cooperated in a program to obtain two aircraft for flight research. Ship #1 was given NASA number 702, and ship #2 was number 703. The first aircraft arrived at Ames on 23 March 1978.
After wind-tunnel testing in Ames’ 40 x 80 foot wind-tunnel, the aircraft began its contractor flight tests at Ames on 23 April 1979. Bell, U.S. Army and Marine Corps pilots flew it on 140 separate missions over the next year before turning the aircraft over to Ames. That center, in turn, chose to perform the initial flight research at the Dryden Flight Research Center, Edwards, CA, where aircraft number two began flight research with Dryden pilots on 3 October 1980, followed by aircraft number one (previously the wind-tunnel model) the following year.
The aircraft were powered by twin Lycoming T-53 turboshaft engines connected by a cross-shaft that drove two three-bladed, 25 foot diameter metal rotors. The engines and main transmissions were located in wingtip nacelles to minimize the operational loads on the cross-shaft system and, with the rotors, tilt as a single unit. For takeoff, the proprotors and their engines were used in the straight-up position where the thrust is directed downward. The XV-15 was then able to climb vertically into the air like a helicopter. In this VTOL mode, the vehicle could lift off and hover for approximately one hour. Once off the ground, the XV-15 had the ability to fly in one of two different modes. It could fly in a helicopter mode or an airplane mode. When operating as a conventional airplane, the XV-15 could cruise for more than two hours.
The successful flight research with the XV-15 Tilt-Rotor testbed led to the military’s V-22 Osprey and to the possibility of using tilt-rotor aircraft as a solution to the problem of crowded airports and highways.
Bell/Boeing V-22 Osprey
A V/STOL assault transport designed to supersede the aging/conventional large helicopters built by Boeing and Sikorsky, the V-22 Osprey is a tilt-rotor hybrid rotory/fixed-wing aircraft offering an excellent combination of payload and range. It can takeoff and land like a helicopter, but, once airborne, its blades can be rotated to convert the aircraft to a turboprop airplane capable of high-speed, high-altitude flight.
The V-22 Osprey is the first aircraft designed from the ground up to meet the needs of all four U.S. armed services. The aircraft can transport U.S. Marine Corps assault troops and cargo using its medium lift and vertical takeoff and landing (V/STOL) capabilities. It meets U.S. Navy requirements for combat search and rescue, fleet logistics support, and special warfare support.
Boeing is responsible for the fuselage, landing gear, digital avionics, electrical and hydraulic systems, performance and flying qualities. Boeing partner Bell Helicopter Textron is responsible for wing and nacelle, propulsion, rotor, empennage (complete tail system), ramp, overwing fairing and the dynamics.
The V-22 Osprey made is maiden flight on 19 March 1989. Since that time, the first and fifth prototypes have crashed, leaving only three aircraft for testing. The V-22’s induction into active service is planned for 2000.
Boeing V-22 Osprey Service Requirements
- U.S. Air Force (Special Operations Command): The Air Force SOF/USSOCOM has the most stringent mission requirement for the V-22. Due to the anticipated extended exposure to a high threat environment, the CV-22 will the capability to travel 500 nautical miles at or below 500 feet above ground level, locate a small landing zone, infiltrate and exfiltrate a team of 18 special operations forces and return to base. This must be done covertly at night and, if necessary, in adverse weather. The CV-22 will have enhanced survivability by virtue of the Electronic Warfare suite specific to the SOF mission as well as meeting the survivability standards identified for the “baseline” MV-22 weapons system. This V-22 variant is slated to replace the MH-53J and MH-60G and augment the MC-130 fleet in the USSOCOM Special Operations mission. (Required quantity: 30)
- U.S. Marine Corps: As a replacement for the CH-46E and CH-53D Marine Corps assault helicopters, the MV-22 tilt-rotor aircraft is a V/STOL medium lift assault, self-deployment, and sustained land operations capable aircraft. Designated as the “baseline” variant, the MV-22 must provide combat assault transport of Marines in the initial assault waves and follow-on stages of amphibious operations and subsequent operations ashore. It must also be capable of supporting the following secondary mission tasks: combat assault transport of supplies and equipment, evacuations and maritime special operations, mobile forward area refueling and rearming operations, casualty evacuation, and tactical recovery of aircraft and personnel (TRAP) operations. The aircraft must therefore be self-deployable, capable of handling 24 fully-equipped combat troops, capable of operationally lifting external loads up to 10,000 lbs and able to operate in adverse weather, day or night from air capable ships. (Required quantity: 360)
- U.S. Navy: The United States Navy has a requirement for a specially configured V-22 variant known as the HV-22. These will be used for shipborne combat search and rescue and fleet logistics support. As of 1999, detailed requirements have not yet been established. (Required quantity: 48)
The U.S. Marine Corps and U.S. Navy require that the V-22 be compatible with below-decks stowage, flight deck elevators, flight deck edge clearance for the wheels, control island clearance for the rotors, rapid turn-around times, and the limited availability of maintenance facilities on aircraft carriers or air capable ships. The Osprey’s airframe footprint, tail configuration, and stowed dimensions are all affected by these requirements. Of these, the most defining characteristic is the requirement to operate from a launch and recovery spot located next to the control tower or island of a helicopter carrier. The clearances to the island structure on one side (12 feet 8 inches) and the deck edge on the other side (5 feet) define a very precise limitation on overall wingspan and available rotor diameter.
The V-22’s tilt-rotor design can also be adapted to missions not specified by current service requirements. With its speed, range and internal cargo capacity, the Osprey could be adapted to meet numerous other missions including aerial refueling, medical evacuation, and executive/VIP transport.
Boeing V-22 Osprey Advantages
Better Than A Helicopter
The V-22 provides vertical takeoff and hover performance similar to a conventional helicopter. It can takeoff from small, unimproved, or confined areas and still fly long-range missions. Because of the combination of high speed, long-range and large payload capacity, it offers the warfighter significant productivity increases compared to a conventional helicopter.
Better Than An Airplane
The V-22 has the efficiencies of a twin turboprop without the need to takeoff or land on a runway. It can operate from small unimproved sites or a large variety of surface ships and still insert combat troops and equipment over long ranges while hovering over a landing zone.
Boeing V-22 Osprey Features
The V-22’s propulsion system consists of dual counter rotating proprotors attached to gearboxes driven by Allison T406-AD-400 turboshaft engines. The engines, proprotor gearboxes, tilt-axis gearboxes, proprotor controls, and infrared suppressors are all housed in the rotating nacelle on the end of each wing. An interconnecting drive shaft transfers power from each nacelle to the mid-wing gearbox. This is the heart of the tilt-rotor technology.
Under normal, two engine operations, each engine delivers its power to its corresponding proprotor through the proprotor gearboxes. Only a small amount of power (511 hp max) is transferred down the pylon mounted drive shaft, through the tilt-axis gearboxes and down the interconnecting drive shaft to the mid-wing gearbox. The mid-wing gearbox contains the auxiliary power unit (APU), the constant frequency generator and the variable frequency generator. The mid-wing gearbox transmits power between the left and right interconnecting drive shafts without changing speed or direction of rotation. (During single engine operation, power is distributed from the remaining engine to both proprotors through the interconnecting drive shaft.)
The V-22 is equipped with two counterrotating three-bladed proprotors. The blades are constructed primarily of composite material with a metallic leading edge abrasion strip and integral de-ice blanket. These blades are attached to the proprotor hub which transmits drive torque to the proprotor. The proprotor controls respond to cyclic, directional, and thrust lever inputs in both helicopter and conversion modes, and to thrust inputs alone in airplane mode. Vibration reduction has been designed into the entire proprotor assembly including the pendulum dampers used to reduce the vibratory loads generated by the rotation of the proprotors.
The entire rotor, transmission, and engine nacelles tilt through 90 degrees in forward rotation and are directed forwards for forward flight, and through 7 degrees 30′ in aft rotation for vertical take-off and landing. Both engines have cross-coupled transmissions so either engine can power the rotors in the event of an engine failure.
Flight Control System
The Osprey has both conventional airplane and conventional tandem-rotor helicopter control surfaces. The primary flight controls consist of cyclic sticks located in front of each pilot, thrust control levers mounted to the left of each seat, and floor-mounted directional pedals. These controls are part of a fully digital, electronic, fly-by-wire system. Because it is completely digital, the V-22’s flight control system offers exceptional flexibility to incorporate the actuator control command for both fixed-wing and rotary-wing control surfaces and provides a smooth transition between airplane and helicopter flight modes.
The process of rotating the nacelles to transition between helicopter and airplane modes is called conversion. This process is simple, straight forward, and easy to accomplish. The amount and rate of nacelle tilt can be completely controlled by the pilot or can be performed automatically by the flight control system. The minimum time to accomplish full conversion from hover to airplane flight mode is 12 seconds. A tilt-rotor can fly at any degree of nacelle tilt.
During vertical take-off, conventional helicopter controls are utilized. As the tilt-rotor gains forward speed to between 40 and 80 knots, the wing begins to produce lift and the ailerons, elevators, and rudders become effective. At this point, rotary wing controls are gradually phased out by the flight control system. At approximately 100 to 120 knots the wing is fully effective and cyclic pitch control of the proprotors is locked out.The conversion from airplane flight to a hover simply reverses the process described above. Since the fuselage and wing are free to remain in a level attitude during the conversion, there is no tendency for the wing to stall as speed decreases. Rotor-borne lift fully compensates for the decrease in wing lift.
Because there is great variability available between aircraft and nacelle attitude, 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 tilt-rotor can have a safe and comfortable transition, free of the threat of wing stall.
The V-22’s cockpit features side-by-side seating for the pilot and co-pilot. The flight crew have a Pilot’s Night Vision System and a Honeywell integrated helmet display. The cockpit is equipped with six night vision goggle compatible displays. The cabin and the cockpit are NBC (nuclear, biological and chemical warfare) protected with a positive pressure filtered air system.
The Marine Corps MV-22 variant has a folding crashworthy jumpseat for a third crew member mounted on the forward face of the cabin/cockpit door. The USAF Special Operations CV-22 variant has a folding, crashworthy jumpseat with an extended seat pan allowing a flight engineer access to the center and overhead consoles.
The U.S. Air Force and U.S. Navy variants are equipped with a terrain following AN/APQ-174 multi-mode radar. They also contain an AN/AAQ-16 FLIR (Forward Looking Infrared) night vision system which is mounted on the nose. This system contains a 3-5 micron indium antimonide staring focal plane array.
The V-22’s electronic warfare suite includes an AN/AAR-47 missile warning system which is a passive electro-optical missile warner to protect the aircraft from surface to air missiles. It consists of four electro-optic sensors with photomultipliers, a signal processing unit, and a cockpit display. The aircraft is also equipped with a radar and infra-red threat warning system and chaff and flare dispensers with 60 rounds of dispensables. The CV-22 will have the Suite of Integrated Radio Frequency Measures (SIRFC), being developed by ITT Avionics.The aircraft also has provision for nose and ramp gun mounts.
The V-22 has a cargo compartment, measuring approximately 6 x 6 x 24 feet, with a rear loading ramp that provides easy access. It is fitted with crash-resistant foldaway seats, arranged twelve on each side and inward facing, for 24 fully-equipped combat troops. For the medical evacuation role, the cabin can accommodate 12 litters (stretcher patients) and a team of medical officers.
The internal cargo handling equipment includes a cargo winch and pulley rated at 2,000 lbs, roller rails, and shock absorbing cargo tie down rings fitted on the cabin floor. A cargo door is located on the right of the fuselage immediately behind the cockpit accompanied by a rear loading ramp/door assembly at the back of the fuselage which is hydraulically operated.
The aircraft is also fitted with two external cargo hooks, either of which can support a load of 10,000 lbs and a rescue hoist. If the retractable hooks are used together for stability, the combined capacity can be up to 15,000 lbs.The rescue hoist consists of a hydraulically powered winch mounted on a removable boom and support shaft. The winch holds 250 usable feet of 5.32 in diameter corrosion-resistant steel cable. It has a rated capacity of 600 lbs with a 2.5g limit load factor.
The Osprey’s cargo compartment is capable of accepting cargo pallets or containers as large as 68 inches wide, 66 inches high, and 250 inches long, as long as the object is capable of achieving the necessary restraint criteria.
Blade Fold/Wing Stow Sequence
The V-22 is fully shipboard compatible with the world’s first complete blade fold and wing stowage system. It is able to operate off all US Navy L-class amphibious ships, the LHA/LHD assault carriers, and can be stowed on full size CV/CVN carriers.
For stowage the wings are rotated to lie above and parallel to the fuselage to create a compact rectangular volume. The automatic wing and rotor folding sequence can be completed in 90 seconds in a 60 knot wind. It can be interrupted or stopped at any point to facilitate maintenance. Manual operation is possible in the event of a system failure.
Once the sequence is initiated, the proprotors turn themselves to a predetermined position. This is called indexing the blades. When complete, one blade on each side is pointing inboard. The remaining four blades automatically fold until all six blades are pointing inward, parallel to the wing. Next, the nacelles begin rotating from the upward, helicopter position to the horizontal, cruise position. Simultaneously, the wing swivels clockwise until the starboard nacelle is positioned in front of the aircraft’s nose and the port nacelle is positioned above the fuselage just forward of the vertical tails. This completes the blade fold/wing stow sequence. When folded, the V-22 fits into a space 63 feet long, 18 feet 5 inches wide, and 18 feet high.
Boeing V-22 Osprey Specifications
|Official Designation||Boeing V-22A Osprey|
|Service Designations||CV-22 (USAF), HV-22 (USN), MV-22 (USMC)|
|Primary Role||Tactical V/STOL transport|
|Secondary Role||Special operations|
|Original Contractor||Bell Helicopter Textron and The Boeing Company|
|Operator||United States Air Force, Navy, Marine Corps|
|Length: 57 feet, 4 inches (17.47m);|
Width: 84 feet, 7 inches (25.76m);
Height: 22 feet, 7 inches (6.86m)
|Length: 62 feet, 7 inches (19.05m);|
Width: 18 feet, 5 inches (5.61m);
Height: 18 feet (5.47m)
|Wingspan||45 feet, 10 inches (13.96m)|
|Height at Tail||17 feet, 7 inches (5.34m)|
|Cargo Hold||Length: 24 feet, 4 inches (7.41m);|
Width: 5 feet, 11 inches (1.80m);
Height: 6 feet (1.83m)
|Engines||Two Allison T406-AD-400 engines|
|Horsepower||6,150 shp (4,588kW) per engine|
|Cruise Speed||316 mph (509km/h) in airplane mode;|
213 mph (343km/h) in helicopter mode
|2,100 nm (3,889km)|
|Service Ceiling||26,000 feet (7,925m)|
|Operating Weight||33,140 pounds (15,032kg)|
|Fuel Capacity||13,850 pounds (6,282kg)|
|Max Payload||Internal: 20,000 pounds (9,072kg);|
External: 10,000 pounds (4,526kg) per hook;
Rescue Hoist: 600 pounds (272kg)
|Number of Seats||24|
|Max Takeoff Weight||Vertical: 52,870 pounds (23,981kg);|
Short-running: 57,000 pounds (25,855kg);
Self deployment: 60,500 pounds (27,442kg)
|Basic Crew||Three (pilot, co-pilot, crew chief)|
|Total in Service||Unknown|