One of the main issues in dealing with conventional military aircraft is the need for readied and prepared takeoff and landing facilities that can accommodate the requirements of fixed wing aircraft. Studies into how to utilize aviation equipment to their fullest potential with the smallest requirement for landing and takeoff facilities have been carried out dating back to the end of the Second World War. In the last year of the Second World War, Germany's airfields were effectively out of commission, her air force the Luftwaffe was all but destroyed and Allied air forces had free reign over the cities of the Reich as they bombed city after city into ruin. With marauding formations of American Boeing B-17 Flying Fortresses and British Avro Lancasters flying in seemingly endless waves over the territory of the Reich unchallenged, the German leadership turned to Germany's most brilliant designers to come up with an answer to the unchallenged nature of Allied air superiority.
The designers of the Focke Wulf aircraft company were the leaders in VTOL (Vertical Take Off & Landing) research in Germany. Their desgn known as the Triebflügel or 'Thrust Winged Fighter"was designed as an interceptor using three jet engines mounted on three arms effectively a rotor blade configuration that mounted on a ring assembly supported by ball bearings allowed free rotation around the fuselage. When the jet engines were operated, speed would increase and the air flow allow the aircraft to obtain lift. The pitch of the blades could be altered and lift fully obtained. With the jet engines mounted on the wing tips, the aircraft avoided the effects of reaction torque, which is the force that would cause the fuselage to want to spin opposite the direction of the engines.The fighter sat on its tail and during take off the helicopter like effect of the engines would carry the fighter into the air more effectively a gyrodyne and then could transition into level flight. To land, the aircraft slowed its speed and pitch was reduced until the aircraft reached a vertical attitude. Power would gradually be reduced until the aircraft rested on the landing gear of its tail empennage.
Despite being a successful design in wind tunnel tests achieving a speed equivalent of Mach 0.9, it never made it into production as the Allies soon entered Germany and Germany surrendered in May of 1945.
After the war the United States made attempts for VTOL technology in the form of the Ryan X-13 Vertijet which was a project pursued by the United States Navy. The Soviet Union also made attempts in VTOL technology but the pursuit for VTOL technology was no better developed than in the United Kingdom.
The Rolls Royce company was influential to VTOL design in a jet powered aircraft when it developed the Thrust Measuring Rig nicknamed 'The Flying Bedsted' in 1953. The first British VTOL aircraft was the Short SC.1 of 1953, which was used as a testbed to study the effects of VTOL flight and the transition to and from forward flight in a VTOL machine. Two of these machines were built and tested by Britain's Royal Aircraft Establishment. It holds the unique status of being the world's first VTOL aircraft equipped with a fly by wire control system which allowed for three differing modes of control for the craft's aerodynamic surfaces and thrust nozzles.
With the results of the studies conducted using the Short SC.1, the British began looking into using a single engine for both vertical and horizontal flight by altering the path of thrust. The Bristol Siddeley Engine corporation responded by developing the Pegasus, a turbofan engine capable of using rotating ducts to direct thrust in varying angles. By directing thrust downwards the engine could power the craft to take off vertically and while using the same thrust, the ducts could be swivelled to power a jet into forward flight.
The design for the Pegasus came from a NATO request for a light tactical support fighter and can about at a time when the Hawker Aviation Company was looking for a replacement for its Hawker Hunter airframe. The proposed replacement aircraft was ultimately cancelled in response to the 1957 Defence White Paper. In the face of deep defence budget cuts, the Hawker Siddeley company developed a prototype airframe to mount its Pegasus engine, known as the P.1127 project. The P.1127 went through a series of tests with the first prototype serial number XP831 delivered in July 1960 for test and evaluation. It made its first static test tethered to the ground at Dunsfold Aerodrome in Surrey, England on 21 October 1960. This was soon followed by the first free flight hover on 19 November 1960. The second prototype XP836 conducted a conventional take off on 7 July 1961. Both prototypes XP831 and XP836 began to close the gap between vertical take off and forward flight a feat which was achieved on 8 September 1961.
Following the initial successes of the P.1127 project, four more prototypes were ordered along with improved variants of the Pegasus engine. One type known as the Pegasus III was capable of utilizing 15,000 lbf of thrust. The first carrier landing of a VTOL aircraft was carried out in 1963, when the first prototype landed aboard the Royal Navy's HMS Ark Royal aircraft carrier. The fifth prototype XP980 mounted a taller tail fin and anhedral, and the final P.1127 designated XP984 introduced the swept wing concept to the design. It would mount the newer Pegasus V engine and would be designated a new prototype aircraft known as the Kestrel FGA.1. The first three prototypes of the P.1127 crashed during testing including one at the 1963 Paris Air Show, however all the test pilots involved walked away from the crashes unhurt.
Soon interest in the design was shown by both the Royal Air Force and Royal Navy based on a NATO requirement for a supersonic aircraft capable of vertical take off and landing. The NATO program was ultimately cancelled. Both the RAF and RN continued to pursue the supersonic aircraft however issues soon arose by the varying requirements for each individual service. The Royal Air Force wanted a supersonic strike aircraft capable of low level operations, while the Royal Navy wanted a twin engined air superiority fighter. In 1964, the P.1154 program which was a supersonic version of the improved P.1127 known as the Kestrel was cancelled. The Royal Navy subsequently adopted the McDonnell Douglas F-4 Phantom II while the RAF showed interest in the development of the British Aircraft Corporation TSR-2 strike & reconnaissance aircraft.
With the cancellation of the P.1154 program the P.1127/Kestrel program did not die away and the Royal Air Force issued Requirement ASR 384 for a V/STOL (Vertical/Short Take Off & Landing) subsonic ground attack aircraft. The first P.1127 (RAF) aircraft as they were designated arrived in mid 1965 following an order for six pre-production aircraft made to Hawker Siddeley. The maiden flight of the aircraft was 31 August 1966. Upon delivery of the first six aircraft a further order for 60 airframes designated as Harrier GR.1 was received in 1967.The original design name Kestrel, was honored by the Royal Air Force, who christened the aircraft the 'Harrier', a small bird of prey capable of hovering in flight.
The production model Harrier GR.1 made its maiden flight on 28 December 1967,and it was officially adopted into Royal Air Force military service on 18 April 1969. The new RAF aircraft utilized the swept wing design used on P.1127 aircraft XP984, as well as the taller tail fin and anhedral first flown on the P.1127 XP980. The initial RAF conversion unit to receive the airframe was No. 1 Squadron located at RAF Wittering near Stamford, Lincolnshire. The Royal Navy did not give up its interest in the V/STOL aircraft either as it initiated a series of tests using a ski-jump system at RNAS Yeovilton near Yeovil, Somerset in 1977. The results of these tests were favorable and in 1979, the Royal Navy ordered that the ski jump system be installed on all Royal Navy aircraft carriers. This soon followed with the development of a variant of the Harrier known as the Sea Harrier FRS.1, the FRS designation standing for Fighter, Reconnaissance, Strike.
It was during this time that due to nationalization Hawker Siddeley became a part of the British Aerospace Corporation. The Harrier was utilized as a single seat ground attack aircraft, although its unique maneuverability and characteristics allowed for the type to engage enemy aircraft at short ranges. The upgraded Pegasus engines utilized a system of four thrust vectoring nozzles to direct the thrust generated from its turbofan engine, two for the bypass flow and two for the jet exhaust. Small reaction nozzles were fitted in the nose, tail and wingtips for the purpose of balancing the aircraft in vertical flight. It used a landing gear system of two fuselage mounted landing gear and two outrigger landing gear mounted on the wingtips. It was fielded with four wing and three fuselage hard points for mounting weapons, sensor pods or external fuel tanks.
The unique V/STOL capability of the new Harrier allowed it to be deployed from very small quickly prepared clearings, or from helipads or established airfields. NATO military planners theorized that established airfields would be vulnerable and likely targets for attack during high intensity conflict.The capability to distribute Harrier equipped squadrons amongst a number of random small sites known as 'alert pads' near the front line made it a prefered weapon of military strategists. Vertical Takeoff capabilities exhibited by the type also benefitted from reduced fuel usage which allowed the aircraft to mount more weaponry for the close air support role.
The first Harrier Squadron to reach West Germany, was assigned to RAF Wildenrath near the town of Wildenrath, North Rhine-Westphalia in 1970. A second Harrier squadron was established in West Germany in 1972. In 1977, three squadrons of RAF Harrier GR.1 aircraft were relocated to RAF Gütersloh. From this position, the Harrier squadrons would be positioned closer to the Inner German Border and the probable frontline in the event of a war with the Soviet Union. The aircraft loaded with a variety of rockets and bombs would be located nearby to provide close air support capabilities to the ground commander. Soon after arriving in Germany, one of the three squadrons was disbanded and its aircraft were redistributed amongst the other two units.
The Harrier GR1 aircraft in West Germany were employed in both the close support and reconnaissance roles. RAF Germany units heavily deployed the type across RAF airfields in Germany as a deterrent capability against Warsaw Pact armored forces. The aircraft were frequently operated from rough, camouflaged positions where the aircraft could launch attacks on advancing military forces emerging from the German Democratic Republic. Thus the small bird of prey capable of hovering in flight successfully established a military legacy, in the face of adversity. Nearly lost to become but a footnote in history like the countless attempts at VTOL technology from the past, the British succeeded at employing a tool of war capable of operating from the harshest of environments. The Harrier would endure at the frontline of British military deployments for years to come. From the campaign in the Falklands, to later campaigns it saw many further incarnations including a collaborative effort with the American McDonnell Douglas corporation, the AV-8B variant developed for the United States Marine Corps.