Hawker Siddeley Harrier GR.1

Design work on the P.1127 formally began in 1957 under Sydney Camm and Ralph Hooper of Hawker and Stanley Hooker of the Bristol Engine Company, and the first prototype flew in October 1960. That test bed led to the Kestrel of the tripartite evaluation, and when the supersonic P.1154 was cancelled the RAF settled for something simpler: an update of the subsonic Kestrel. It issued Requirement ASR 384 for a V/STOL ground-attack jet, known as the P.1127 (RAF). In late 1965 it ordered six pre-production aircraft, the first of which took off from Dunsfold on 31 August 1966. In early 1967 Hawker received a formal order for 60 production aircraft, and at that point the type was designated Harrier GR.1, after the bird of prey.

Although the two looked alike, roughly 90 per cent of the Kestrel's airframe was redesigned for the Harrier. The GR.1 used the Pegasus 6, known as the Pegasus Mk 101 in RAF service, rated at 84.7 kN, and received new air intakes with auxiliary blow-in doors to provide the airflow needed at low speed. The wing was modified to increase its area and the landing gear was strengthened. There were five hardpoints, two under each wing and one under the fuselage, and two pods with 30 mm ADEN cannon could be fitted beneath the belly. The Kestrel's basic avionics gave way to a navigation and attack system with an inertial platform, originally developed for the P.1154: the Ferranti FE541, which presented information to the pilot through a head-up display and a moving map. Every RAF GR.1 carried it. The aircraft were built at two plants, Kingston upon Thames and Dunsfold, where initial testing also took place.

The first production GR.1 flew on 28 December 1967, and the type officially entered RAF service on 1 April 1969. The first unit equipped was No. 1 Squadron, which began converting at RAF Wittering in April that year. Its tasks were close air support, reconnaissance and ground attack, exploiting the ability to operate away from conventional runways. In the event of war, No. 1 Squadron was earmarked for operations in Norway as part of Allied Forces Northern Europe.

Early in 1969, while the aircraft was still in testing and had not yet entered service, the RAF decided to enter two Harriers in the Daily Mail Transatlantic Air Race. The intended lead pilot, Mike Adams, was injured beforehand when the nosewheel collapsed on a Harrier he was testing. Vertical take-off meant the jets could start and finish close to the city-centre checkpoints: in London the aircraft left from a coal yard next to St Pancras station, temporarily designated RAF St Pancras, and in New York it landed on a 29 by 29 metre pad set up by the US Marine Corps on the planned site of the United Nations International School beside the East River. Victor tankers refuelled the Harriers over the Atlantic, and the aircraft flew with ferry wingtips to improve cruise performance. The westbound flight was made by Squadron Leader Tom Lecky-Thompson in GR.1 XV741 and was completed on 5 May 1969: from the Post Office Tower to the Empire State Building it took 6 hours 11 minutes, 5 hours 57 minutes of it in the air, the shortest overall time from London to New York. The return leg was flown by Williams in GR.1 XV744 on 9 May. In between, on 7 May, both Harriers hovered on either side of the Queen Elizabeth 2 as she arrived in New York on her maiden voyage. XV741 is now displayed at Brooklands Museum and XV744 at the Tangmere Military Aviation Museum.

In 1970 two Harrier squadrons were formed at RAF Wildenrath in West Germany, and a third followed two years later. When No. 3 Squadron arrived at Wildenrath on 1 January 1972, it shared the base with IV and 20 Squadrons, both flying the GR.1. That same month, while signing the handover papers as station commander, George Black, later an Air Vice-Marshal, heard an almighty bang: a Harrier had crashed into a German village, killing its pilot. The GR1 had been in service for only about three years, and the idea of operating it from the field, the very reason for its deployment to Germany, was still in its infancy. Out of that grew the Harrier Field Force: from camouflaged rough sites, away from vulnerable airfields, the aircraft was expected to strike armoured columns advancing from East Germany.

The US Marine Corps AV-8A was broadly similar to the RAF's GR.1, and the initial AV-8As also carried the FE541, although in the Marines' aircraft it was replaced by a simpler weapon-aiming computer to speed turnaround between missions.

The GR.1 was the first step in the series. The GR.1A changed the engine to the 91.4 kN Pegasus 10 (Pegasus Mk 102): 17 were built new and a further 41 GR.1s were converted to that standard. Later all remaining GR.1s and GR.1As were brought up to GR.3 standard, with improved sensors, a nose-mounted laser tracker, electronic countermeasures and the Pegasus Mk 103. In all, 61 GR.1s were built. Besides the two race aircraft, two P.1127 prototypes preserve a GR.1 wing: XP980 at the Fleet Air Arm Museum, Yeovilton, and XP984 at Brooklands.