The Birth of the Harrier – A Diamond Anniversary P1127 – First hover On 21 October 1960 at Hawker’s Dunsfold airfield in Surrey a small, strange looking aircraft with an unusual design of undercarriage squatted on a metal grid covering a deep pit in the concrete hard standing. The pilot was in the cockpit and several ground observers, wearing ear defender headsets which were wired to the aircraft, surrounded this peculiar machine. It came to life as its Bristol BE53 turbofan engine was started and with a unique whine, increased to ground idle for few minutes before its four exhaust nozzles were rotated down and full power was selected. The noise level rose to a high decibel roar and the machine staggered unsteadily clear of the ground. This was the first attempt to achieve a vertical take-off and brief hover of the unique P1127 which, for this pioneering “flight”, was stripped of all surplus weight and tethered at a maximum altitude of only about four feet to ensure a level of safety. The men behind this successful demonstration were Sir Sydney Camm, the Hawker chief designer and Sir Stanley Hooker the Bristol chief engineer. As work progressed, letters held in the Trust archives confirm that the initial formal relationship between the two principals relaxed to the level of “Syd and Stan” and both men had confidence in their engineers. The detailed project work was delegated to Ralph Hooper at Kingston for the airframe and to Gordon Lewis in Bristol for the propulsion system which had been conceived specifically for the Hawker project. Lewis’ unique design was based on an adapted turbofan but with the cold bypass flow diverted through a pair of rotatable nozzles and the remaining air entering the conventional combustion system before being exhausted through a separate pair of nozzles. Hooper, Lewis and their engineers worked very closely to ensure the subsequent success of the project where the challenge to both design teams was to ensure that with the nozzles pointed down, the gross vectored thrust coincided with the centre of gravity of the aircraft. With high pressure puffer ducts at the airframe extremities, fed from the engine’s high pressure compressor, the aircraft was balanced in the hover. Prior to the first flight, Hooker is claimed to have asked of Camm "I suppose you are going to do some conventional flying first Sydney?" and Camm replied "What for?" Hooker said "Well you know, just to make sure it’s a nice aeroplane, and that everything is under control". Camm is said to have replied, "Hawker aeroplanes are always beautiful, nothing wrong with a Hawker aeroplane, not going to bother with that; vertical first time” and so it proved. Within a month the tethers had been removed and the P1127 finally had hovered in free air, clear of the high energy jet efflux in ground effect which had affected the handling during earlier attempts. By March the following year it had flown as a conventional aircraft and in September only eleven months after its first tentative hover the P1127 had achieved a vertical take-off and transition to conventional flight before decelerating to the hover for a vertical landing. This was the gestation of the project which became the iconic Harrier, the world’s first vertical and short take-off and landing (VSTOL) combat aircraft, powered by the remarkable pioneering BE53 engine, the Pegasus. The busy flight test and development programme led to minor systems improvements and changes to the airframe design while the engine was developed to produce more thrust with better handling both in hovering and conventional flight so that three years after that first tentative hover, the P1127 had dived at supersonic speeds and had landed on an aircraft carrier while underway at sea. P1127 at sea So, what were the attractions of jet VSTOL combat aircraft? The concept enabled fighters to operate from austere strips, away from vulnerable airfields and, at sea, to fly from smaller ships without the need for extensive and cumbersome catapult and cable arrester gear. The P1127 was not the first jet powered machine to hover and a number of research designs, which were neither promising nor practical, had flown in the USA. In Britain in the early 1950s, Rolls-Royce pioneered the concept of jet lift with its thrust measuring rig (TMR) which had two Nenes mounted back to back with their exhausts deflected downwards and constrained in a gantry. Suitably restrained it “flew” in 1953 with its first untethered hover taking place the following year. Known colloquially as the Flying Bedstead, it performed vertical take offs and landings and manoeuvred in the hover although conventional flight was impossible. The ungainly Short SC1, which carried five RB108 engines, four for lift and one for propulsion, benefitted from TMR research data and had achieved a vertical take-off, transition to conventional flight and return to a vertical landing many months before the first hover of the P1127. However carrying a battery of lift engines used solely for take-off and landing was judged to be complicated and inefficient hence the SC1 was retained solely as a research vehicle. Other countries had investigated jet VSTOL but none had resulted in a successful practical design other than the Yak38 Forger which served with the Soviet Navy from 1976 to 1991. Initially, development of the first two P1127s was financed privately by Hawker until the government recognised the potential and a few months before that first hover, some funding was provided for a further four development aircraft, but solely for research. At the same time Ministry of Defence aspirations were still constrained by the short sighted policies following the infamous 1957 Defence White Paper which, inter alia, had cancelled all future manned fighters. In the early 1960s there was much scepticism in both the Royal Air Force and Royal Navy about the perceived benefits of VSTOL as there was a common, but inaccurate, belief that aircraft designs with such a capability would have performance limitations. By early 1962 however, Hawker had demonstrated the validity of the P1127 design, and despite the modest British enthusiasm, NATO had become attracted to a ground attack aircraft with a VSTOL capability. Military support developed and there was an almost grudging agreement by the government that Britain should be involved in such a requirement, thus reversing its previous short-sighted policy that there would be no more manned combat aircraft. On paper, Hawker’s P1127 concept was a suitable basis for the development of a supersonic multi role fighter to meet a NATO Basic Military Requirement (NBMR3), with the aim of equipping the RAF and RN with a multi-role common airframe, designated the P1154. To confirm the feasibility of VSTOL combat aircraft, an interim project based on an austere development of the P1127 aircraft, was submitted in early 1962 to fulfil the requirement for an operational trials unit. This was planned to be a small squadron, part of the RAF Central Fighter Establishment at West Raynham in Norfolk. As a result of overt interest from lobbies within the United States and West Germany, the British government approached these two nations with an offer to collaborate on the project and to seek contributions towards its cost. Following acceptance by all three nations in May 1962, Hawker received a formal contract to procure materials for the construction of nine Kestrel aircraft, the improved version of the P1127. The project was authorised and funded as a tri-national enterprise involving Britain, the USA and Germany with the aim of ascertaining the operational viability of deployed VSTOL operations. In October 1964, the Tri-partite Evaluation Squadron (TES) was formed at RAF West Raynham, staffed by a diverse mix of experienced military pilots and ground crews from Britain, the United States and West Germany, commanded by Wing Commander David Scrimgeour (RAF) who had been my Hunter squadron commander in 1960. Before flying the Kestrel, each TES pilot received a week's ground training on the Pegasus engine at Bristol and a week's ground instruction at Dunsfold including a three-hour flight conversion briefing given by Bill Bedford. The international ground crew were given a similar pattern of training in the unique features of the engineering support for the P1127, particularly the Pegasus turbofan with its special vectoring nozzles. Kestrel FGA1 The purpose of the squadron was to evaluate the suitability of VSTOL aircraft for deployed operations, compare different handling and methods for take-off and landing, develop normal flight operating procedures, perform instrument flight assessments, conduct night flight operations, and explore jet-borne manoeuvring throughout the Kestrel's flight envelope. The trial lasted for six months and confirmed the viability of VSTOL or, more accurately, Short Take Off and Vertical Landing (STOVL) operations from dispersed sites. Interestingly, neither the US Marine Corps nor the Royal Navy were represented and neither were trials conducted at sea although the P1127 had flown previously from HMS ARK ROYAL to prove the ease of operation from ships at sea. Just as the tripartite trial was underway in 1965, the new government’s defence review cancelled the P1154 project and ordered instead McDonnell F-4 Phantoms, modified with Spey turbofans. Also sixty of a much improved version of the Kestrel, designated the P1127 (RAF), were ordered to retain design expertise at the big Hawker factory at Kingston and to retain the STOVL features which the Tripartite trial had proved to be a highly desirable capability. Although resembling the Kestrel visually the much modified aircraft, now confirmed as the Harrier, was slightly heavier, had a bigger wing and was equipped fully as a combat aircraft with a self- contained navigation and attack system, podded guns and five pylons for carrying external stores such as weapons and fuel.