William Edward Willoughby "Teddy" Petter (8 August 1908, Highgate in Middlesex – 1 May 1968, Béruges) was a British aircraft designer. He is noted for Westland's wartime aeroplanes, as well as the Canberra, the early design of the Lightning, and his last plane, the Folland Gnat.
Early life
Edward 'Teddy' Petter was the eldest of the three sons and one daughter of Sir Ernest Petter (co-founder of Westland Aircraft Works) and his wife, Angela Emma. Because his father spent much time in London, Teddy's early childhood was spent mostly with his mother, from whom he inherited a strong religious conviction and firm ethical principles. He was educated at Marlborough College in Wiltshire then Gonville and Caius College, Cambridge. During his first two years at Cambridge he focused his studies on subjects relevant to oil engines, the traditional product of Petters Limited, but in his third year he concentrated on aerodynamics and aircraft engineering. In 1929 he was awarded a first class in the mechanical sciences tripos and shared the John Bernard Seely prize in aeronautics.
Career
Westland
Early career Petter joined Westland Aircraft Works as a graduate apprentice in 1929 and for the next 2 1/2 years he worked in every department, not seeking any favour despite being the chairman's son. In the drawing office it was noted that he was a very poor draughtsman but had good ideas. Years later he said "I looked on this as sheer drudgery at the time, but knew afterwards that without workshop knowledge I would never have become a designer".
In May 1932 he was appointed personal assistant to the managing director, Robert Bruce, a position previously held by Petter's friend and colleague Harald Penrose. Bruce did not welcome the appointment and ignored him, leaving Petter spare time to modify and compete an Austin 7. Despite his interest in sports cars, Petter had no interest in learning to fly. Penrose gave him a flying lesson at this time, but later commented that Petter had a 'lack of the requisite sensitivity coupled with hopeless judgment of speed and distance'.
His father appointed Petter to the board in May 1934, making him technical director (at the age of 26) in preference over more experienced engineers such as Arthur Davenport and Geoffrey Hill. This was not welcomed by the older members of the management, ultimately prompting Bruce and Hill to resign, and placing the older and more experienced Davenport in an intolerable position as his subordinate. One of his first actions as technical director was to terminate development of Hill's Pterodactyl, a pioneering tailless swept-wing aircraft.
However, other business decisions by Ernest Petter infuriated Teddy. In July 1935 Ernest Petter convened a shareholders meeting to propose a merger with British Marine Aircraft for the purpose of expanding Westland's workshops. This proposal was thwarted by Teddy and Peter Acland who threatened to resign. But in July 1938 Ernest Petter sold the controlling shares in Westlands to John Brown Ltd, forming Westland Aircraft Limited as a separate company, with Eric Mensforth brought in to share the managing directorship with Peter Acland. Teddy saw the loss of family control of the company as the loss of his birthright, and this dispute would divide the Petter family for years, not being resolved until shortly before Ernest Petter's death in 1954.
Lysander
The Air Ministry was initially reluctant to award Westland contracts due to Petter's inexperience, but his reputation as a successful designer was strengthened after it was demonstrated that the automatic slats on the PV 7 were both effective and reliable. As a result, and after internal discussion, the Air Ministry added Westland to the list of bidders for Specification A.39/34 (the replacement for the Hawker Hector army co-operation aircraft). Petter started the design by interviewing the Army Cooperation pilots and ground crew. Based on this information, he placed pilot visibility, the ability to take off and land in small spaces, and ease of ground maintenance as the prime requirements. The resulting design, the Westland P8 (later named the Lysander), was clearly an evolution of Westland's high-winged monoplane designs, but Petter incorporated a number of innovative features including extensive use of extruded sections throughout the airframe, something that would be a feature in his future designs.
The early flight testing revealed attitude control problems that the wind tunnel tests had not predicted. Petter instructed Penrose to conceal these problems from Ernest Petter. Later, when these problems had been addressed by a larger, variable-incidence tailplane, it was realised that if a landing was aborted and the throttle opened up fully, the Lysander could rear up and stall. While Penrose and RAF test pilots lobbied for modifications, Petter refused because redesign would affect production. Also, in his zeal to reduce weight, Petter had used glider fabric instead of specification Irish linen to cover the wings on the second prototype. This nearly caused a disaster when an RAF pilot dived it to the limit, causing the fabric on the top surface to tear off.
Whirlwind
Petter's next fixed-wing aircraft design was a radical departure from the Westland's typical high-wing fabric-covered airframe. The Westland P9 was a low winged twin-engined aircraft employing the latest technology. It was designed to meet Air Ministry specification F.37/35, which called for a single-seat cannon-armed fighter, at least 40 mph faster than a contemporary bomber and not less than 330 mph at 15,000 ft. To obtain this performance Petter and Davenport chose to minimise drag; the two Rolls-Royce Peregrine engines were fitted in closely streamlined nacelles, and their radiators were fitted inside the wing inboard sections (something that would be later copied in the de Havilland Mosquito and the Hawker Tempest I). In the two prototypes the engine exhaust was routed through the fuel tanks in the wings to reduce parasitic drag. The Air Ministry thought that this was dangerous and insisted that conventional exhaust stacks be fitted.
The airframe was of thin-walled stressed skin construction, with the rear fuselage skinned in magnesium alloy. Like the Lysander, it made extensive use of extrusions in the airframe. To reduce the landing distance the wing incorporated automatic Handley Page slats coupled to the Fowler Flaps, with the radiator grilles also coupled to the flap control, which was advanced at the time.
The prototype first flew in September 1938, and while it was one of the fastest and most heavily armed fighters of its era, faster than the Spitfire Mk 1, its development was problematic and protracted. The engines overheated, the hydraulic engine controls were imprecise, the slats slammed open, and production was slow.
Petter was frustrated by its lack of operational status in the RAF. In November 1940, he wrote a memo to Sholto Douglas stating "The Whirlwind is probably the most radically new aeroplane which has ever gone into service... New ideas I am afraid, even with the greatest care, always mean a certain amount of teething trouble... I really do not think these troubles have been any worse than they were on, say, the Spitfire... " In reply Sholto Douglas wrote, "... it seems to me that your firm is concentrating on producing large numbers of Lysanders, which nobody wants... instead of concentrating on producing Whirlwinds which are wanted badly." Shortly after this exchange 263 squadron became operational, but Petter always regretted that the Whirlwind was not available for the Battle of Britain and blamed Eric Mensforth for the delay in production.
Spitfire development By 1942 Westland was building mostly Spitfires under contract. One of the problems with the early marks of Spitfire was variability of longitudinal stability, leading to aircraft getting dangerously out of control and contributing to the risk of structural failure . Petter made a significant contribution to improving the longitudinal stability of the Spitfire because he was the first to appreciate that aerodynamic modification to the elevator could provide additional stability. On his own initiative he had Penrose collect flight test stick force data and trim curves on a Spitfire at various centre of gravity loadings, then produced a prototype elevator with a bulged aerodynamic section, which produced a 'remarkable' improvement in stability, later being known as the 'Westland Elevator'.
Welkin
In 1940, the Air Ministry was motivated by the threat of high altitude bombers such as the Junkers Ju 86P, to issue a specification for a high altitude interceptor, F4/40, followed by a revision F7/41 in 1941. Petter submitted two designs. His first was an innovative low-drag aircraft (P13), which featured a pair of staggered Merlins in the fuselage, one behind and slightly above the other, driving a pair of contra-rotating propellers. His second submission was a conventional design (P14), describing it as 'a logical development of the successful Whirlwind...". This was selected and became the Welkin.
Specification F7/41 required a minimum speed to at with a maximum ceiling of . The Air Ministry also wanted low altitude manoeuvrability and a +9G ultimate load factor. The speed was equivalent to a Mach number of 0.62 while the loading condition caused Petter to select a thick wing section which would later be demonstrated to have a critical Mach number of 0.6. The significance of the thick wing section may not have been understood by Petter because compressibility effects had only started to be encountered by aircraft designers. During test flying the effect of compressibility was experienced by Penrose who wrote, "In speed runs at the ceiling the wings and fuselage sometimes shook as though the machine was bumping over cobblestones." Petter was reluctant to believe Penrose or accept that the wing would not be acceptable for high speed at altitude.
While the cabin pressurisation was innovative and worked well, the heat from the compressor "was like sitting in an oven". Petter was unconcerned and reluctant to modify the system, Penrose thought that "It was the machine's performance which interested him, not that of the pilot". Petter devised a better method for cooling the cabin only after Penrose developed pneumonia attributed to this problem.
Penrose said later that "At this time Petter's intellect put him ahead of most contemporary designers as shown by his introduction of pressurization and extensive use of remote electrical controls which subsequently became standard practice. By the time of the Welkin he had learnt the lesson that it takes as long to develop an aeroplane as to design it... Petter was an outstanding organiser and could envisage construction time-scales with greater knowledge than Fearn and Wheeldon. ...it was his lack of understanding people and their motives that became his major failure."
B1/44 proposal Westland's successful manufacture of Spitfires meant that Petter was well thought of by Sir Wilfrid Freeman, chief executive officer at the Ministry of Aircraft Production (MAP) and by N. E. Rowe, its director of technical development. Discussions between all three led to Specification B1/44 for a jet-powered replacement for the de Havilland Mosquito bomber. Petter developed his proposal for B1/44 as a private venture. This was a 56 ft span medium bomber powered by two Metrovick F.2/4 "Beryl" engines located within the fuselage and he persuaded the Westland board to put up capital to manufacture a mockup of the fuselage. This was his fifteenth wartime design study and his final design for Westland.