The concept of aircraft with tilting propellors to achieve vertical takeoff goes back to the late 1940s. The first true tiltrotor to fly was built by the Transcendental Aircraft Corporation. The Model 1G had a maximum hover gross weight of 794kg and was powered by a single reciprocating engine within the fuselage. It made its first hover flight on June 15th 1954, but crashed in July 1955 without ever achieving a full conversion from hover to forward flight.

Bell Aircraft had performed some tiltrotor design studies in the late 1940s, and in 1951 the company's XV-3 Convertiplane was selected as a technology demonstrator. The XV-3 had a maximum weight of 2177kg. Like the Model 1G it was powered by a single radial engine in the fuselage. The first XV-3 performed its first hover on August 11th 1955, and its first in-flight rotor tilt on July 11th 1956. However, the aircraft crashed on October 25th 1956 as a result of rotor instability. The second XV-3 had a redesigned rotor system, but still suffered from rotor instability. It did, however, make the first complete conversion of a tilt-rotor aircraft on December 18th 1958, and went on to make over 100 more.

Even as a proof-of-concept design the XV-3 was only marginally successful - it could do little that couldn't be done by a helicopter. But it had more value as a research program, and advanced the knowledge needed to build and operate tilt-rotor aircraft.

During the 1960s a number of tilt-rotor proposals were made but none were actually turned into hardware until April 1973, when Bell Helicopter was selected to build two Tilt-Rotor Research Aircraft (TRRA), which were given the designation XV-15. The XV-15 had a maximum gross weight of 6804kg for STOL takeoff and landing, and 6464kg for vertical operations. It had an engine at each wingtip, which were connected by cross shafting in the wing.

The XV-15 made its first hover on May 3rd 1977, and its first full conversion on July 24th 1977. On Jun 17th 1980 the XV-15 set an unofficial speed record for rotorcraft of 301 knots in level flight. Later, it achieved an altitude of 26000ft (7925m).

In June 1981 the XV-15 was displayed at the Paris Air Show, where it was seen by US Navy Secretary John Lehman and other officials.

The XV-15 was one of the most successful VSTOL experimental aircraft programs. It flew for more than 20 years, executing over 5000 conversions with over 300 pilots. During V-22 development the XV-15 was a ready demonstrator and pilot training asset. The surviving aircraft was eventually retired on September 16th 2003.

The V-22 story really started in 1969, when the US Marine Corps identified a need to replace its CH-46 medium-lift helicopter fleet, and issued a formal Operational Requirements document which requested procurement of a replacement aircraft. This request was un-funded right through the 1970s. In 1981 the Marine Corps appealed to the then Navy Secretary, John Lehman, to get the CH-46 replacement program (now called V/HXM) funded. The V/HXM requirement was ambitious. It needed to be able to carry 24 troops over a range of 200 nautical miles at a speed of 250 knots. The speed requirement alone meant that a conventional helicopter would be unlikely to be acceptable.

In December 1981 US Secretary of Defense Weinberger announced DoD's intention to develop a multi-service mission aircraft for all US services. During 1982 the Joint Services Operational Requirements group identified ten missions that a multi-service aircraft could perform, and recommended a tiltrotor as the most promising design. The formal Joint services advanced Vertical lift (eXperimental) program, or JVX, was initiated in December 1982. JVX immediately subsumed the V/HXM program. As the Marine Corps had the largest requirement, the Navy was assigned executive management of the program, and the Marine Corps Department of Aviation, with the basic requirement, took oversight responsibilities. The US Air Force wanted JVX to replace its special-operations HH-3E and MH-53 helicopters. Long range was vital, as the Tehran hostage rescue mission in 1980 became overly complicated because of limited helicopter range. The Navy had a need for JVX to replace many ageing logistic support helicopters. An anti-submarine version was also mooted but didn't come to anything. The Army appeared to have several missions which could be fulfilled by JVX.

The JVX Request for Proposals was issued in December 1982, which called for responses by mid-1983. The Navy's intent had been to select two contractors to complete in the 23-month preliminary design phase. A 'simulator flyoff' would evaluate each design against the JVX requirement. At this time the Pentagon, in line with its new acquisition policy, encouraged Bell Helicopter Textron, which was the clear leader in the competition thanks to its tiltrotor experience, to team up with another company. The two would then compete for annual production lots.

The Bell/Boeing-Vertol Joint Venture Agreement was concluded in early 1982. The Bell-Boeing team conceived the Model 901-X, which was essentially a scaled-up XV-15 based on Bell's earlier D-327 design, which had been drawn up to meet the V/HXM requirement. At this time the type's engine was not known, as a suitable 5700 shp unit was not available. This caused a six-month slip in the first flight target date.

The Bell-Boeing team submitted the Model 901-X against the RFP on February 17th 1983. As it was obvious that only a tiltrotor could meet the JVX requirement, other companies declined to compete. DoD considered cancellation, but eventually decided to continue with the program. Bell-Boeing was awarded a $68.7 million Stage 1 preliminary design contract on April 26th 1983.

Stage 1 was completed in May 1984, and a Stage 2 contract was awarded. There was a lot of wind tunnel testing - 7000 hours in nine facilities in total.

The team submitted their Full-Scale Development (FSD) proposal in August 1984. Various changes were made, and the proposal was re-submitted in February 1985.

On January 15th 1985 the JVX was designated the V-22 Osprey, with the Marine version becoming the MV-22 and the Air Force version the CV-22. The Navy's search and rescue version would be the HV-22.

At this time the number of development aircraft was reduced from seven to six, with two static test airframes. Plans still called for the first production aircraft to be delivered in 1991, with 913 being delivered thru 2001: 552 for the Marines, 231 for the Army, 80 for the USAF and 50 for the Navy. The cost of a single V-22 was estimated at $24 million. These numbers were beginning to look increasingly unrealistic.

In December 1985 the engine choice was finally resolved with the selection of the Allison T406-AD-400, which was based on the T56 turboshaft. The T406 was expected to produce a maximum output of 6150 shp (4585 kW).

The JVX program entered Full-Scale Development in May 1986 following a Milestone II review by the Defense Systems Acquisition Review Council (DSARC). A fixed-price $1.714 billion 7-year FSD contract was awarded to Bell-Boeing.

In 1987 the Army withdrew from its V-22 procurement commitment. Bell/Boeing conducted budgetary cost estimates for the SV-22, and commenced a V-22 Executive Transport variant (VV-22) feasibility study. The US Special Operations Command (USSOCOM) formed and took acquisition responsibility for the SOF variant CV-22 from the Air Force.

The first of six FSD-prototype aircraft (163911) made its first flight on March 19th 1989.

In April 1989, Secretary of Defense Cheney cancelled the V-22 program in the FY 1990 Amended President's Budget, citing affordability reasons. At this time the unit cost was estimated at $35 million, and with the Army pulling out, total production was down to 602 aircraft.

The V-22 question caused friction between Cheney and the US Congress throughout his tenure. DoD spent some of the money Congress appropriated to develop the aircraft, but congressional sources accused Cheney, who continued to oppose the Osprey, of violating the law by not moving ahead as Congress had directed. Cheney argued that building and testing the prototype Osprey would cost more than the amount appropriated.

In the spring of 1992 several congressional supporters of the V-22 threatened to take Cheney to court over the V-22 issue. A little later, in the face of suggestions from congressional Republicans that Cheney's opposition to the Osprey was hurting President Bush's re-election campaign, especially in Texas and Pennsylvania where the aircraft would be built, Cheney relented and suggested spending $1.5 billion in fiscal years 1992 and 1993 to develop it. He made clear that he personally still opposed the Osprey and favored a less costly alternative.

Also in 1992 Bell/Boeing completed tanker kit, turret gun system, and RF jammer engineering investigations. The Deputy SecDef directed that the V-22 should compete with helicopters, yet a new requirement for a minimum airspeed of 180 knots (eliminating all helo competition!) was introduced by the Marine Corps. The USSOCOM issued an MV-X Operational Requirements Document.

In October 1992 the Navy terminated the FSD airframe contract with Bell-Boeing (with one aircraft not yet completed) and awarded a contract to the same companies to begin V-22 Engineering and Manufacturing Development (EMD). Bell-Boeing was placed under a cost-plus contract for the version to replace the CH-46.

In 1993 the Clinton administration, which supported the V-22, took office. The V-22 was funded in the Four Year Defense Program for the first time in four years. The Under Secretary for Defense (Air) directed the V-22 program to continue as a joint effort, and directed USSOCOM to participate. The 180kt restriction introduced in 1992 was withdrawn. Congress passed the FY94 Defense Authorization/Appropriation Bill, with funds identified for the continuation of V-22 into production. The Appropriations Bill added funds for restart the CV-22 program. At this time the plan was to 446 Ospreys for $37.3 billion, or more than $80 million apiece. The Marines would receive 348, the Navy 48 and the Air Force 50.

In December 1994, following an extended period of review of operational requirements and medium-lift alternatives, the Defense Acquisition Board held a Milestone II+ review, formally approving the EMD program. The restructured EMD program called for continued developmental testing of two of the remaining FSD-prototype aircraft; design and development of four EMD aircraft incorporating sufficient weight reduction and other improvements as needed to comply with the approved operational requirements; and testing of three EMD aircraft.

In 1995 V-22 Low Rate Initial Production was started with a $1 billion funding cap.

The first of the EMD aircraft, aircraft number 7 (164939), made its first flight in February 1997. The program continued reasonably on track until 2000, when two of the LRIP Ospreys crashed, killing 23 people. After the second crash the Osprey was grounded until May 2002 for redesign of hydraulics and wiring in the engine nacelles, plus improved flight control software. Initial operational capability for the V-22 was rescheduled for 2005.

Lt Col Kevin Gross, USMC, was awarded the Marine Corps Aviation Association's James Maguire Award for 2004. The Maguire Award is given each year in recognition of the most significant professional contribution made to enhance Marine aviation.

The citation for the award notes that in his capacity as V-22 Government Flight Test Director, Lt. Col. Gross "was responsible for the highly successful accomplishments of all development tests and flight test prerequisites for entry into operational assessment of the MV-22. Additionally, his brilliant technical competence, superb performance of duty, and unequaled leadership skills were dominant factors that contributed to a renewed confidence in the V-22 program at the highest levels of the Department of Defense. The total dedication and professional judgment of Lt. Col. Gross have helped shape the future of Marine Aviation, paving the way for this transformational technology in the 21st Century, and providing warfighters with a capability that will be vital to the defense of the nation."

Following the successful completion of extended operational testing of the Osprey, conducted by the Marine Corps in summer 2005, the Defense Acquisition Board gave the go-ahead for full-rate production of the aircraft on September 29th 2005. This will increase production from 11 per year to a maximum of 48.

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