McDonnell Douglas AV-8B Harrier II
The McDonnell Douglas 'AV-8B Harrier II' is a single-engine ground-attack aircraft that constitutes the second generation of the Harrier family, capable of vertical or short takeoff and landing. The aircraft is primarily employed on light attack or multi-role missions, ranging from close air support of ground troops to armed reconnaissance. The AV-8B is used by the United States Marine Corps, the Spanish Navy, and the Italian Navy. A variant of the AV-8B, the British Aerospace Harrier II, was developed for the British armed forces, while another, the TAV-8B, is a dedicated two-seat trainer.
The project that eventually led to the AV-8B's creation started in the early 1970s as a cooperative effort between the United States and United Kingdom, aimed at addressing the operational shortcomings of the first-generation Hawker Siddeley Harrier. Early efforts centered on a larger, more powerful Pegasus engine to dramatically improve the capabilities of the Harrier. Because of budgetary constraints, the UK abandoned the project in 1975. Following the UK's withdrawal, McDonnell Douglas extensively redesigned the earlier AV-8A Harrier to create the AV-8B. While retaining the general layout of its predecessor, the aircraft incorporates a new, larger composite wing with an additional hardpoint on each side, an elevated cockpit, a redesigned fuselage and other structural and aerodynamic refinements. The aircraft is powered by an upgraded version of the Pegasus. The AV-8B made its maiden flight in November 1981 and entered service with the USMC in January 1985. Later upgrades added a night-attack capability and radar, resulting in the AV-8B and AV-8B Harrier II Plus versions, respectively. An enlarged version named Harrier III was also studied but not pursued. The UK, through British Aerospace, re-joined the improved Harrier project as a partner in 1981, giving it a significant work-share in the project. Following corporate mergers in the 1990s, Boeing and BAE Systems have jointly supported the program. Approximately 340 aircraft were produced in a 22-year production program that ended in 2003.
Typically operated from small aircraft carriers, large amphibious assault ships and simple forward operating bases, AV-8Bs have participated in numerous military and humanitarian operations, proving themselves versatile assets. U.S. Army General Norman Schwarzkopf named the USMC Harrier II as one of several important weapons in the Gulf War. It also served in Operation Enduring Freedom in Afghanistan, the Iraq War and subsequent War in Iraq, along with Operation Odyssey Dawn in Libya in 2011. Italian and Spanish Harrier IIs have taken part in overseas conflicts in conjunction with NATO coalitions. During its service history, the AV-8B has had a high accident rate, related to the percentage of time spent in critical take-off and landing phases. USMC and Italian Navy AV-8Bs are being replaced by the Lockheed Martin F-35B Lightning II, with the USA expected to operate its Harriers into 2027.
Development
Origins
In the late 1960s and early 1970s, the first-generation Harriers entered service with the Royal Air Force and USMC but were limited in range and payload. In short takeoff and landing configuration, the AV-8A carried less than half of the smaller A-4 Skyhawk's payload, over a more limited radius. To address this, Hawker Siddeley and McDonnell Douglas began joint development of a more capable version of the Harrier in 1973. Early efforts concentrated on an improved Pegasus engine, designated the Pegasus 15, which was being tested by Bristol Siddeley. Although more powerful, the engine's diameter was too large by to fit into the Harrier easily.In December 1973, a joint American and British team completed a project document defining an advanced Harrier powered by the Pegasus 15 engine. The advanced Harrier was intended to replace the original RAF and USMC Harriers, as well as the USMC's A-4 Skyhawk. The aim of the advanced Harrier was to double the AV-8's payload and range and was therefore unofficially named AV-16. The British government pulled out of the project in March 1975 owing to decreased defense funding, rising costs, and the RAF's insufficient 60-aircraft requirement. With development costs estimated to be around £180–200 million, the United States was unwilling to fund development by itself and ended the project later that year.
Despite the project's termination, the two companies continued to take different paths toward an enhanced Harrier. Hawker Siddeley focused on a new larger wing that could be retrofitted to existing operational aircraft, while McDonnell Douglas independently pursued a less ambitious, though still expensive, project catering to the needs of the U.S. military. Using knowledge gleaned from the AV-16 effort, though dropping some items—such as the larger Pegasus engine—McDonnell Douglas kept the basic structure and engine for an aircraft tailored for the USMC.
Designing and testing
As the USMC wanted a substantially improved Harrier without the development of a new engine, the plan for Harrier II development was authorized by the United States Department of Defense in 1976. The United States Navy, which had traditionally procured military aircraft for the USMC, insisted that the new design be verified with flight testing. McDonnell Douglas modified two AV-8As with new wings, revised intakes, redesigned thrust nozzles, and other aerodynamic changes; the modified forward fuselage and cockpit found on all subsequent aircraft were not incorporated on these prototypes. Designated YAV-8B, the first converted aircraft flew on 9 November 1978. The aircraft performed three vertical take-offs and hovered for seven minutes at Lambert–St. Louis International Airport. The second aircraft followed on 19 February 1979 but crashed that November because of an engine flameout; the pilot ejected safely. Flight testing of these modified AV-8s continued into 1979. The results showed greater than expected drag, hampering the aircraft's maximum speed. Further refinements to the aerodynamic profile yielded little improvement. Positive test results in other areas, including payload, range, and V/STOL performance, led to the award of a development contract in 1979. The contract stipulated a procurement of 12 aircraft initially, followed by a further 324.Between 1978 and 1980, the DoD and USN repeatedly attempted to terminate the AV-8B program. There had previously been conflict between the USMC and USN over budgetary issues. At the time, the USN wanted to procure A-18s for its ground attack force and, to cut costs, pressured the USMC to adopt the similarly designed F-18 fighter instead of the AV-8B to fulfill the role of close air support. Despite these bureaucratic obstacles, in 1981 the DoD included the Harrier II in its annual budget and five-year defense plan. The USN declined to participate in the procurement, citing the limited range and payload compared with conventional aircraft.
In August 1981, the program received a boost when British Aerospace and McDonnell Douglas signed a memorandum of understanding, marking the UK's re-entry into the program. The British government was enticed by the lower cost of acquiring Harriers promised by a large production run, and the fact that the U.S. was shouldering the expense of development. Under the agreement, BAe was relegated to the position of a subcontractor, instead of the full partner status that would have been the case had the UK not left the program. Consequently, the company received, in man-hours, 40% of the airframe work-share. Aircraft production took place at McDonnell Douglas' facilities in suburban St. Louis, Missouri, and manufacturing by BAe at its Kingston and Dunsfold facilities in Surrey, England. Meanwhile, 75% work-share for the engine went to Rolls-Royce, which had absorbed Bristol Siddeley, with the remaining 25% assigned to Pratt & Whitney. The two companies planned to manufacture 400 Harrier IIs, with the USMC expected to procure 336 aircraft and the RAF to procure 60.
Four full-scale development aircraft were constructed. The first of these, used mainly for testing performance and handling qualities, made its maiden flight on 5 November 1981. The second and third FSD aircraft, which introduced wing leading-edge root extensions and revised engine intakes, first flew in April the following year; the fourth followed in January 1984. The first production AV-8B was delivered to the Marine Attack Training Squadron 203 at Marine Corps Air Station Cherry Point on 12 December 1983, and officially handed over one month later. The last of the initial batch of 12 was delivered in January 1985 to the front-line Marine Attack Squadron 331. These aircraft had F402-RR-404A engines, with 21,450 lb of thrust; aircraft from 1990 onwards received upgraded engines.
Upgrades
During the initial pilot conversion course, it became apparent that the AV-8B exhibited flight characteristics different from the AV-8A. These differences, as well as the digital cockpit fitted instead of the analog cockpit of the TAV-8A, necessitated additional pilot training. In 1984, funding for eight AV-8Bs was diverted to the development of a two-seat TAV-8B trainer. The first of the 28 TAV-8Bs eventually procured had its maiden flight on 21 October 1986. This aircraft was delivered to VMAT-203 on 24 July 1987; the TAV-8B was also ordered by Italy and Spain.With export interest from Brazil, Japan, and Italy serving as a source of encouragement to continue development of the Harrier II, McDonnell Douglas commenced work on a night-attack variant in 1985. With the addition of an infrared sensor and cockpit interface enhancements, the 87th production single-seat AV-8B became the first Harrier II to be modified for night attacks, leaving the McDonnell Douglas production line in June 1987. Flight tests proved successful and the night attack capability was validated. The first of 66 AV-8Bs was delivered to the USMC in September 1989. An equivalent version of the AV-8B also served with the RAF under the designation GR7; earlier GR5 aircraft were subsequently upgraded to GR7 standards.
In June 1987, as a private venture, BAe, McDonnell Douglas, and Smiths Industries agreed on the development of what was to become the AV-8B Plus with the addition of radar and increased missile compatibility. The agreement was endorsed by the USMC and, after much consideration, the Spanish and Italian navies developed a joint requirement for a fleet of air-defense Harriers. The United States, Spain, and Italy signed an MoU in September 1990 to define the responsibilities of the three countries and establish a Joint Program Office to manage the program. On 30 November 1990, the USN, acting as an agent for the three participating countries, awarded McDonnell Douglas the contract to develop the improved Harrier. The award was followed by an order from the USMC in December 1990 for 30 new aircraft, and 72 rebuilt from older aircraft. Italy ordered 16 Harrier II Plus and two twin-seat TAV-8B aircraft, while Spain signed a contract for eight aircraft. Production of the AV-8B Harrier II Plus was conducted, in addition to McDonnell Douglas' plant, at CASA's facility in Seville, Spain, and Alenia Aeronautica's facility in Turin, Italy. The UK also participated in the program by manufacturing components for the AV-8B.
File:AV-8B Harrier II Plus spanish navy.jpg|thumb|right|A Spanish Navy AV-8B Plus in-flight. The nose houses the Hughes APG-65 pulse-Doppler radar.|alt=Starboard view of gray jet aircraft in-flight against a blue sky
Production was authorized on 3 June 1992. The maiden flight of the prototype took place on 22 September, marking the start of a successful flight-test program. The first production aircraft made its initial flight on 17 March 1993. Deliveries of new aircraft took place from April 1993 to 1995. At the same time, the plan to remanufacture existing AV-8Bs to the Plus standard proceeded. On 11 March 1994, the Defense Acquisition Board approved the program, which initially involved 70 aircraft, with four converted in fiscal year 1994. The program planned to use new and refurbished components to rebuild aircraft at a lower cost than manufacturing new ones. Conversion began in April 1994, and the first aircraft was delivered to the USMC in January 1996.