- Yes
- No
- 11.3
- 11.7
- 12.0
- Higher/Lower/Other
- I voted no in first question
McDonnell Douglas AV-8B Harrier II
Description
Spoiler
Seeking to anticipate an RAF and USMC requirement for a Harrier follow-on even as the aircraft was entering service, Hawker Siddeley and McDonnell Douglas joined forces to consider a new airframe, while Rolls-Royce paired up with Pratt & Whitney in engine development. Using as their basis earlier P.1184 and P.1185 series of schemes, the partners evolved the prematurely designated “AV-16” and its 25,000lb st (111.2kN) Pegasus Mk15 powerplant. Originally and provisionally known as “AV-8C” (“AV-8B” was then reserved for the trainer which became the TAV-8A) and then as “XV-16”, the aircraft began as a Harrier fuselage with supercritical section wings. The US Navy, also in the market for a V/STOL combat aircraft expressed no interest and used its superior position to order the Rockwell XFV-12A in 1972, but the project - of little use to the USMC - came to naught.
The trans-Atlantic partnership persevered with more advanced versions of the “AV-16”, which almost re-invented the P.1154 but generated little enthusiasm. Finally, in March 1975, Britain’s government withdrew from this “Super Harrier” project, claiming that there was insufficient common ground to make continued partnership viable. A little over six years later, Britain bought back into the US program as a sub-contractor - rather than the full partner it could have been . and went to order 110 of what was then called the AV-8B Harrier II. In America, meanwhile, McDonnell Douglas had kept the Harrier alive by creditable exercise in refinement which improved the aircraft whilst keeping costs to a minimum. With energetic support of the USMC, the St. Louis designers shunned uprated engines as a quick (but expensive) way of bettering the Harrier and instead devoted their attentions to doubling the AV-8A’s payload/range capability through structural and aerodynamic means.
A new, larger, carbon-fiber supercritical wing, together with widespread use of same material in the forward fuselage and other areas, is combined with lift-improvement devices to boost performance, while a raised cockpit with new nav/attack avionics enhances combat potential. With the same engine power, the AV-8B carries 70% more external ordnance and 50% more internal fuel, part of which can be traded off for 400% more external fuel tankage. Furthermore, it needs 60% fewer maintenance manhours, 60% less ground-support equipment and can deliver its expanded war load with 200% improved accuracy.
The new wing was first flown on 9 November 1978, attached to the 11th AV-8A (158394), which thereby became the first of two YAV-8B. It has 14.5% more area and 20% more span, although sweep is reduced by 10%. That makes the aircraft a little slower than its predecessor - about the only field in which it is inferior. Wing area of 230sq ft (21.37m2) excludes the leading-edge root extensions added as a result of parallel British studies of a larger winged Harrier. Three weapon pylons are under each wing, the outriggers of which have been transferred from tips to give a shorter wheel track for improved taxiing and operations from narrow publics roads. Sitting 12in (30cm) higher than before for a better view of a target and opposing aircraft, the pilot enjoys HOTAS controls and a far roomier and ergonomically efficient cockpit.
Construction of the first McDonnell Douglas YAV-8B Harrier II (BuNo 158394) in 1978
The bigger wing increases the lifting capacity, provides two extra weapons hardpoints and accommodates more internal fuel, but its carbon-fiber construction makes it 331lb (150kg) lighter than if made of metal. Similarly, 150lb (68kg) is saved by building the forward fuselage from the same material. By making air intakes a more efficient shape, the equivalent of a saving of a further 600lb (272kg) was obtained. For reasons of heat resistance, the rear fuselage - which is built by BAe in Britain - remains much as before. Maximum weapon loads on the individual positions are 1,000Ib (454kg) on the centerline; 2,000Ib (907kg) on each wing inboard and center pylons; and 620Ib (281 kg) on the outboard.
Aircraft built prior to 1990 had 21,450Ib (95.42kN) available from a Pegasus 11-21 powerplant (F402-RR-406 and -406A, equivalent to the RAF Mk.105), giving a maximum weapon load with rolling takeoff of 9,200lb (4173kg), or a combined weapon-and-fuel total of 17,000lb (7710kg). Maximum takeoff weight is 31,000lb (14,061kg), compared with 25,000lb (11,340kg) for a first generation Harrier. (As an interim measure, the first 16 AV-8Bs had -404 powerplants and a double row of pressure-relief doors around the air intakes.) Recently-built aircraft have, at last, had the whip cracked over their flying horse, which is now persuaded to develop 23,800Ib st (105.87kN), as the Pegasus 11-61 (F402-RR-408). Development of the latter started under the company designation XG15 in 1983, a first bench test following on 22 October 1986. Airborne trials in an RAF Harrier (ZD402) began on 10 June 1989, the engine having the fan pressure ratio raised from 2.3 to 2.6, a new combustor, improved cooling with the use of single-crystal fan blades, and improved reliability and maintainability that double the overhaul interval to 1,000 flying-hours.
Unlike the AV-8A and the AV-8C, the AV-8B featured almost from the start the Hughes AN/ASB-19(V)-2 Angle Rate Bombing System, proven in the A-4M Skyhawk. It was optimized for dive attack profiles and was linked to the new AN/AYK-14 mission computer and the SU-128/A HUD. The first two FSD aircraft initially flew with “solid” noses and extended test instrumentation probes, but later aircraft had distinctive glass nose associated with ARBS. Inside the cockpit, the AV-8B was a very different aircraft to any of its predecessors. Whereas the original Harrier cockpit had been entirely analog (unkindly described by some as an ergonomic slum), the AV-8B used a cockpit based on that designed for the F/A-18 Hornet, which in the late 1980s was regarded as the benchmark modern fighter cockpit with its HOTAS controls and large MFDs.
The Harrier II was made easier to fly in an effort to reduce the high attrition rate. Advances in technology allowed the use of a sophisticated three-axis Sperry Stability Augmentation and Attitude System (SAAHS), linked to a Departure Resistant System (DRS), minimizing pilot workload in the hover and during the transition to and from the hover. The SAAHS even allowed hands-off vertical landings to be made, demonstrated by Bill Lowe in February 1983. A USMC report entitled “Frosty Nozzle” had addressed the EW and secure communications shortcomings of the original AV-8A, and as a result the AV-8C had incorporated a KY-28/TSEC secure voice radio, AN/ALE-39 dispensers, ALR-67 RWR, and provisions for the ALQ-126C DECM pod. These systems were used from the start by the AV-8B, which was also planned to use the troubled ASPJ jammer.
Two programs for further enhancement of the Harrier II’s capabilities have been implemented. First of these, the Night Attack AV-8B, was revealed by McDonnell Douglas in November 1984. A prototype was converted from production aircraft 162966 and flew for the first time on 26 June 1987 with a GEC Sensors FLIR (Forward-Looking Infra-Red) sensor mounted prominently above the nose. In conjunction with a wide-angle HUD, new head-down displays, a digital moving-map system and pilot’s night-vision goggles, this allows the Harrier to operate on clear nights, immediately doubling its combat availability.
Page from World Air Power Journal Volume 6
In 1989 GEC Sensors received an initial £10 million contract for FLIRs for the new Harrier variant. MDD designed a neat installation for it above the nose, allowing ARBS to be retained. The Hughes AN/ASB-19(V) ARBS is a daylight-only device, and is therefor redundant during night operations. The new US night-attack aircraft had a new expanded field of view HUD (20° azimuth by 16°, from 14° azimuth) to allow 1:1 correlation of the FLIR picture (20° azimuth by 13°) overlaid on the HUD. The aircraft also featured a new multi-purpose color display, and a CRT-based digital map display, which retrieved data from an optical compact disc in the Hamilton Standard AN/ASQ-194 data storage set. The pilot was provided with GEC Cats Eyes Generation III NVGs (with a field of view of 40° in azimuth by 30°) giving better peripheral vision, outside the 22° cone covered by the FLIR. The Cats Eyes NVGs featured prisms below the image intensifiers.
The Night Attack Harrier also took advantage of a new engine, the Pegasus 11-61, known in the US as the F402-RR-408. This engine was developed directly from Britain’s XG15 engine technology demonstration program, which had been jointly funded by the British MoD and Rolls-Royce on a 70:30 basis. The new engine had improved fan aerodynamics and single crystal turbine blades, among a host of improvements and modifications. The hot end inspection cycle was doubled to 1,000 hours, and lifecycle cost was asserted to have been reduced by 40 per cent. Engine thrust was dramatically improved, with Rolls-Royce claiming a short lift wet rating of 23,800Ib (105.85kN), and McDonnell Douglas claiming 24,500Ib (108.96kN). Very significantly, the AV-8B(NA) was fitted with four extra Tracor AN/ALE-39 chaff/flare dispensers above the rear fuselage, giving the aircraft a total of 180 flares or chaff cartridges, compared to 60 on the standard, baseline AV-8B. Interestingly, the AV-8B(NA) featured 100% LERX.
AV-8B(NA) in flight. Note the FLIR installation on top of the nose
Cockpit
Weapon systems
Spoiler
The gun fitted to the AV-8B is a development of the GAU-12/U ‘Equalizer’ 25-mm cannon, developed by General Electric. The gun was first trialed on a Harrier in 1980 and entered service with the USMC in 1984. The pods have been fitted with strakes to improve their aerodynamic effect. When the cannon are not fitted, Harriers are flown with long ventral strakes replacing each entire pod. The gun is part of a two-pod system. Each pod is 3.34 m (10.95 ft) long, 350 mm (13.7 in) wide and 470 mm (18.5 in) deep. The starboard pod contains 300 rounds of ammunition on a linear link-less feed system which is connected, at the rear, to the cannon breach system in the port pod. The rotary cannon is driven by a pneumatic system that uses engine bleed air. The motor spins at 9,000 rpm but this is geared down for the cannon. The cannon can speed up to its maximum rate of fire 3,600 rounds per minute, in 0.4 seconds. The GAU-12 can fire a range of high-explosive incendiary, armor-piercing and armor-piercing (discarding sabot) rounds.
Specifications and performance
Spoiler
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Length: 46 ft 4 in (14.12 m)
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Wingspan: 30 ft 4 in (9.25 m)
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Height: 11 ft 8 in (3.55 m)
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Wing area: 243.4 sq ft (22.61 m2)
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Empty weight: 13,086 lb (5,936 kg)
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Max take-off weight: 31,000 lb (14,061 kg)
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Maximum Mach number at altitude: Mach 0.91
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Maximum speed at sea level: (over) 575 knots (1,065 km/h)
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Short take-off run at max take-off weight: 1,330ft (405 m)
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Radius (air-to-ground mission): 480 nm (889 km)
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High-level intercept radius: 627 nm (1,162 km)
Sources
Spoiler
- World Air Power Journal - Volume 32 - Aerospace Publishing Ltd
- World Air Power Journal - Volume 6 - Aerospace Publishing Ltd
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