Boeing AV-8B Harrier II
From Scramble - The Aviation Magazine
|Boeing (McDonnell Douglas) AV-8B Harrier II|
|First Flight||9 November 1978 (YAV-8B)
5 November 1981 (AV-8B)
|Design||McDonnell Douglas, British Aerospace|
|Length||14.1 m||46 ft 4 in|
|Wingspan||9.2 m||30 ft 4 in|
|Height||3.5 m||11 ft 9 in|
|Wing area||22.18 m²||238.7 ft²|
|Empty||5,700 kg||12,500 lb|
|Maximum takeoff weight(VTO)||8,595 kg||18,950 lb|
|Maximum takeoff weight(STO)||14,061 kg||31,000 lb|
|Engines||one Rolls-Royce Pegasus 11-61 turbofan|
|Thrust||96 kN||21,500 lbf|
|Maximum speed||1,065 km/h||mph|
|Close Air Support range (STO, 1h loiter, 12x Mk.82)||167 km||90 nm|
|Strike mission range (STO, Hi-Lo-Hi profile, 7x Mk.82)||1,100 km||594 nm|
|Intercept range (Deck launch, 2x AIM-9, external fuel)||1,161 km||627 nm|
|Combat Air Patrol radius (3h loiter)||185 km||100 nm|
|Service ceiling||15,000 m||50,000ft|
|Rate of climb||12,000 m/min||40,000 ft/min|
Even before the Sea Harrier was in development, British Aerospace and McDonnell Douglas were developing an option for an Advanced Harrier concept. Bristol has developed and successfully tested the Pegasus 15 with its 24,500lbf output rating. This new engine was noticeably larger in diameter than the existing family of Pegasus turbofans driving the existing (and original) British Aerospace (Hawker Siddeley) Harrier. The thinking now was that a whole new airframe could be designed around the Pegasus 15 to take on its potential capabilities. As such, a new joint venture was begun in 1972.
An original agreement between the British and American governments made for acquisition of foreign-made AV-8 Harriers concluded in a 15-year agreement in which McDonnell Douglas could lay claim to local production of the aircraft (this never took place) as well as take on any future derivative development. Seeing it that the Royal Air Force was already looking ahead to the original Harrier's replacement (as were the United States Marine Corps) and the US Navy was looking to replace their ageing fleet of Douglas A-4 Skyhawks, the endeavour was a sound one to undertake. The Advanced Harrier project gained the unofficial designation of AV-16 while Hawker Siddeley assigned the designation of P.1184 to it.
The P.1184 would be a highly-modified version of the original Harrier design. To go along with the new Pegasus 15 series engine was a new wider fuselage. More importantly, a new supercritical wing, was categorized as such in that it featured a specially-designed airfoil that worked to delay the onset of wave drag while at transonic speeds. Like the Harrier before it, the AV-16 would also be of a subsonic aircraft design. The wing would also increase external weapons carrying capacity to six underwing hardpoints while also be able to store more internal fuel increasing range. A second study, becoming the AV-16-S6/P.1185, was developed as a high-altitude supersonic derivative.
Externally, the AV-16-S6/P.1185 would appear as a much streamlined and longer version of the Sea Harrier complete with bubble canopy and single vertical tail fin. The wider fuselage would fit two large side intakes feeding the new Pegasus 15 engine. The outboard riggers would be set behind the innermost underwing hardpoint but the general Harrier layout would be retained.
In March of 1975, citing "insufficient common ground" in the program and (perhaps the most likely culprit) ballooning costs in a shrinking English defence environment, Hawker Siddeley decided to remove themselves from the project altogether. The Pegasus engine was far from being cleared for operational use and further money and time would be needed to make that happen. Couple that with the work needed to design, develop and test a new airframe amongst the diminishing defence budget in Britain and the Hawker Siddeley move becomes understandable. Unable to go at it alone, the United States equally abandoned the project and that was that. Hawker continued some work on finding a "super Harrier" solution but these all came to naught.
McDonnell Douglas, too, worked along with their own Harrier research and came to the conclusion that new, carbon fibre supercritical wing with larger surface area was the answer. Though larger than any other carbon fiber wing of the time, the new assembly would actually weigh less than the original all-metal wing. The original Harrier design was furthered by implementing larger air intakes, slotted flaps, additional air-lift devices and a retractable lateral fence to assist in capturing a cushion of air beneath the aircraft while in hover. The wings had their sweep revised by 4-degrees and were extended to promote better lateral control and cruising. Rolling was improved (as was lateral control by having the underwing-mounted thrusters set further apart. The wider wingspan also promoted the use of an additional underwing hardpoint and greater payloads. The outrigger landing legs were also brought in to provide for a more stable track during ground operation. The forward fuselage was inevitably revised with more composite construction and fitted with a higher cockpit and better canopy bubble canopy while the rear fuselage was lengthened. The vector thrust nozzles were lengthened.
The new changes in the Harrier line brought about by the Americans were now approved for development by the US government on July 27th, 1976. The aircraft would take on the designation of AV-8B and the first such developmental model incorporating the new changes was a modified non-flying AV-8A. Two flyable AV-8As were later converted (though without the fuselage changes) and garnered the development designation of YAB-8B and flown in 1979. Though proving slower than the original Harrier, the design was nonetheless a promising first step and completely fit into the needs for the USMC at the time. 1979 also saw US commitment to the "Harrier II" project in full with the first production order for 336 aircraft placed in the queue with McDonnell Douglas.
By now, the British had come to their senses and BAe was back in talks with McDonnell Douglas. As a benefit, the Americans did end up spending their own money in the development of the Harrier II and all the British would have to do is spend money on acquisition instead of research, development, testing and manufacture. The major drawback to their situation lay in Harrier II's "as is" state which did not allow for much in the way of major modifications to suit British combat needs.
While the original Harrier's development/production saw the British take a majority role in the program while the Americans were given a minor stake in the project, roles were reversed with the production of the Harrier II. McDonnell Douglas would be responsible for up to 60% of the airframe construction while BAe would retain only 40%. Additionally, however, all American AV-8Bs would have final assembly handled at the McDonnell Douglas plant in St Louis, Missouri while all British aircraft would be have their final assembly handled at British Aerospace facility in Dunsford. Engine manufacturing would also be undertaken by a joint venture between Pratt & Whitney in America and Rolls-Royce in Britain.
The first pre-production Harrier II became airborne on November 5th, 1981. Three more such Harrier IIs followed with the final one fitting a common 25mm GAU-12/U multi-barrel Gatling-type cannon for weapons trials. The original Harrier fitted a pair of 30mm ADEN cannons in underfuselage pod fairings but these proved too unique for the American inventory as no other American aircraft fitted the weapon type. While not making use of the ADEN cannon set up, McDonnell Douglas kept the pod fairings for their aerodynamic value and instead used the portside pod fairing for the 25mm cannon and the starboard side pod fairing for 300 rounds of 25mm ammunition. The second YAV-8B prototype went airborne on February 19th, 1979, and initially proved successful but was eventually lost to an engine flame-out incident on November 15th of that year - the pilot ejecting safely.
The first AV-8B was flown on August 29th, 1983 and officially handed over to Training Squadron VMAT-203 at Cherry Point, North Carolina on January 12th, 1984. The first operational squadron became VMA-331 with numbers finally reaching 20 aircraft in March of 1987. The new systems proved more than the original AV-8A pilots could handle so a production order of eight AV-8Bs was cut in favor of developing the all-important two-seat TAV-8B Harrier II. The TAV-8B arrived in Marine hands on July 24th, 1987. Production of all new-build Harrier IIs ceased in 1997 though some were receiving new-build fuselages as recently as 2004.
In 2011, the Royal Air Force Harriers were withdrawn from service, leaving the Royal Air Force and Royal Navy without V/STOL strike aircraft. They were supposed to be replaced by the STOVL F-35B Lightning II. In 2011 however, the UK MoD announced that the F-35C CV model will be ordered and the new aircraft carriers will be fitted with catapult launch and arrester systems.
Delivered from 1981, the AV-8B replaced the AV-8A's in the US Marine Corps. Initially, the AV-8B was powered by the the Pegasus Mk.105 aka F402-RR-406, rated at 96 kN, although only for 15 seconds at take-off - unlimited thrust was 66 kN). Especially in hot conditions, the AV-8B proved to be seriously underpowered when bringing back unused weapons back to the ship, landing vertically. From 1991, Harriers were therefore delivered with the higher thrust Pegasus 11-61 aka F402-RR-408, rated at 106 kN and equipped with Digital Engine Control System. Later, the F402-RR-408A was introduced, greatly improving reliability and maintenance issues.
A further American development was first flown in 1987. The initial AV-8B was only suitable for daylight operations, hence the non-official AV-8B DA (from Day Attack) designation. The AV-8B Night Attack (or AV-8B NA), with FLIR sensor on the nose, night-vision-goggle compatible cockpit lightning, chaff-flare dispensers on the fuselage behind the wings. Because of that the air intake on the tail plane root was extended. A further development of the AV-8B Night Attack is the AV-8B+ Harrier II Plus (or AV-8B RA, from Radar Aircraft), which was first flown in 1992. In a 17 inch lengthened nose, the Rayhteon (Hughes) AN/APG-65(V2) radar, making the aircraft capable to fire the AIM-120 AMRAAM missile. The FLIR sensor was relocated closer to the cockpit. Eventually all Harriers are to be modified accordingly. Exports of this type were Italy (16 ordered) Spain (designated EAV-8B). Both Italy and Spain upgraded their AV-8Bs to AV-8B+ standard, the Spanish model becoming EAV-8B+, powered by the Pegasus 408A turbofan.
The 64th production aircraft was the first two seat trainer, the TAV-8B. This was lengthened, had a larger (higher) tail plane and only had two wing pylons for external stores.
Proposed designation for the AV-8B Night Attack Harrier. Not used.
British version of the AV-8B, powered by the Pegasus 11-21 Mk.105 rated at 96 kN (21,500 lbs). Differences with the American version are mostly avionics and some small external features. Most notable is the Sidewinder pylon fitted on a fairing on the outrigger wheels. The Harrier GR5A incorporated changes in the design in anticipation of the GR7 upgrade. Twenty-one Harrier GR5.A airframes were built.
The Harrier T6 two seater was planned as a T4 with GR7 avionics, because the flight characteristics were believed to be the same. Serious problems on this part resulted in the development of a real Harrier II two seater and the development of the T6 was halted in 1990.
Upgraded GR5 airframes, based on the AV-8B Night Attack variant. Like the American version, fairings were fitted to the nose, one for the ECM system, the other for an RWR. Naturally the avionics were updated and the types first flight was in the end of 1989. All surviving Harrier GR5s were later modified to GR7 standards. The Harrier GR7A is fitted with the uprated Pegasus 11-61 Mk.107 engine, rated at 106 kN (23,800 lbs) thrust. This equates to up to 15 percent more thrust at high ambient temperatures, allowing Harrier GR7s to return to an aircraft carrier without having to dump any unused weapons which along with the reduced maintenance reduces total cost of engine use.
The Harrier GR9 is an avionics and weapons upgrade of the standard GR7. This upgrade, known as the Integrated Weapons programme (IWP), allows the carriage of the latest smart weapons, new inertial navigation and Global Positioning systems (INS/GPS). The GR9 is fitted with new Open Systems Mission Computer, which has greater processing power and growth capacity. The new weapons gradually being integrated are the Paveway IV, Brimstone, Maverick and Storm Shadow missiles, requiring a new Mil-Std-1750 Stores Management System. A Harrier GR7 that has been modified during IWP is designated GR9. Aircraft fitted with the higher rated Pegasus Mk.107 are designated Harrier GR9A. GR9 is continuing in several Capability Upgrades (Caps) and associated Operational Flight Programmes (OFPs). In addition to the Cap upgrades, several UORs were introduced, such as the TERMA self-defence (including the AN/AAR-57 missile warming system and TERMA flare dispenser) and AN/AAQ-33 Sniper advanced targeting pod. After its early retirement in 2010, the 72 aircraft GR.9 fleet was sold to the US Marine Corps in November 2011.
Cap A and Cap A2 were initial attempts to improve some of the functionality lacking inn the GR7 and provided a training aircraft for future GR9 pilots.
In Cap B, all of the baseline aircraft's functionality was restored with limited improvements. Cap B1, released to service February 2006, resolved Cap A issues. The Cap A software supported the TIALD 500 Series pod, the Maverick, new functions for the TERPROM. Cap B2 supported the CRV-7 rocket, secure communications, integration of the Digital Joint Reconnaissance Pod and an advanced bombing mode, which uses the TERPROM/GPWS terrain database. Cap B2 was released for service in August 2006.
Cap D was planned for 2008 but not released because none of the frontline UORs integrated in Cap C could be included in Cap D, making the Cap D unsuitable for operational missions.
Cap E(A) incorporates all Cap C functionality, including the UORs and adds the capability to carry the MBDA Brimstone anti-armour missile, teh new Talon radio in Saturn SJ mode and control of the Digital Joint Reconnaissance Pod via the OSMC. Cap E(A) also provides training modes for the Paveway IV and MBDA Brimstone. The GR9 fleet is expected to be upgraded by the summer of 2010. Capability E(B) will introduce Tactical Information Exchange Capability, providing Link 16 data-link and Improved Data Modem (IDM), along with a second secure radio. Cap E(B) is expected to achieve release to service in the summer of 2011.
British designation for the TAV-8B, used for Harrier GR7 conversion trainer. Its first flight was in 1994 and deliveries started in 1996.
Tentative designation for Harrier GR9 upgrades beyond Capability E. Designation not released.
Designation for 10 upgraded Harrier T10 airframes, its avionics upgraded to Harrier GR9 equivalent.
AV-8B Operational Flight Programs
By 1999, a new C1.0 version OFP software was developed as a basline for the night attack and radar AV-8B models. New weapons are supported such as JSOW, AIM-9X Sidewinder and EW upgrades.
C2.0 integrated JDAM and countermeasures. Redesignated OC.1.2 to reflect the change to Open System Core Avionics Requirements (OSCAR). OC1.3 introduced Advanced Mission Computers and Displays.
C++ high order language. Weapons carriage expansion and countermeasures, Tactical Aircraft Moving Map Capability (TAMMAC), and Aircraft Handling/Readiness Management Plan (RMP).
This is an upgrade to the standard AV-8B aircraft capability. OSCAR with Operational Flight Program H5.0 enables the AV-8B to employ JDAM, Dual Mode LGBs, and provides improvements in radar and AN/AAQ-28 Litening Advanced Targeting Pod capability.
Upgrades to the aircraft communications system for interoperability within the Network-centric warfare operational area. Additionally, the program provides weapons carriage expansion by design, development, integration and testing of additional precision guided and linked programmable weapon capabilities, digital close air support improvements, and video and data link improvements.
H7.0 Block upgrade will provide additional communications/data link upgrades and weapon expansion.
H8.0 provides the follow-on step toward an integrated air picture within the Battle Space Network via Multifunctional Information Distribution System (MIDS)MIDS/RS-Link-16 particiption within the Global Information Grid (GIG).