page_title: Operational Requirement F.155
section_title: Designs
hierarchical_section_title: Operational Requirement F.155 / Designs
caption_attribution_description: English: Hawker P.1103 日本語: Hawker P.1103
context_page_description: Operational Requirement F.155 was a specification issued by the British Ministry of Supply on 15 January 1955 for an interceptor aircraft to defend the United Kingdom from Soviet high-flying nuclear-armed supersonic bombers.
  Discussion about the need for a new supersonic interceptor had been ongoing for some time in the early 1950s, and several designs introduced, but improving radar systems and weapons mooted the need for better aircraft in the short term. Information about new Soviet supersonic bomber designs emerged in 1954, sparking serious consideration for the first time. The Requirement emerged as a much larger and longer-range system than previously studied. The Requirement called for aircraft to be in service by 1962, the same date as the Tupolev Tu-22.
  A number of designs were entered into the competition, many of them based on earlier projects. They generally featured two engines, mounted a powerful new Airborne Interception radar, and would be armed with improved versions of the de Havilland Firestreak missile or an even larger radar-guided design known as "Red Hebe".
context_section_description: Most British manufacturers provided their own suggestions for planes that would meet the specification. At the same time the engine manufacturers were encouraged to develop the necessary powerplants. These included the de Havilland Gyron and Rolls-Royce RB.106.
  Saunders-Roe came up with the P.187: a logical progression from the SR.53 and SR.177 mixed power (rocket and jet engines) interceptors. This gave both rapid acceleration and the capability to operate at high altitudes where jets would be inefficient due to the thin air. Saunders-Roe judged that a big aircraft would be needed to carry 2 IR and 2 radar-guided missiles and the fuel required. A highly streamlined futuristic-looking design (using a drooped nose) it would have been powered by 2 PS.52 jets, a projected development of the Gyron giving 35,000 lb (155.6 kN) of thrust, and 4 Spectre rockets, giving a speed of Mach 2.5 at 76,000 ft (23,165 m). It was judged, at 98,000 lb (3 times the weight of the SR.177) and 84 ft long (26 m), as too big. 
  Fairey drew on their experience with the Fairey Delta 2 (FD2). Their first proposal was a single-engined fighter development of the existing FD2, which was felt to have good export potential although it did not meet the RAF criteria laid down in O.R. F.155. A larger twin-engined design tailored to the operational requirement followed on from this, which became known simply as the "Delta III". A fighter-bomber derivative of this aircraft was also envisaged, with Bristol Olympus 21R engines coupled with a large ventral drop tank giving a much-improved radius of action at low altitude. Fairey, like some of the other manufacturers, felt that carrying 4 missiles was too onerous especially given the size of the radar guided Red Hebe and provided designs based on a payload of only two missiles. They also took the mixed power route for both the FD2 based and the new 'FD3' designs, with both making provision for the fitting of de Havilland rocket engines.
  Going on the basis of the smallest aircraft that could do the job, Hawker's design (the P1103) used a single, albeit powerful, engine – a 25,000 lb (111.1 kN) development of the Gyron. Alternative engines in the form of the Rolls-Royce RB.122, Armstrong-Siddeley P.173 and the Canadian Orenda PS.13 were also options. Two detachable rocket boosters, to give a 3.7-minute boost, were carried in midwing nacelles.
  Armstrong-Whitworth put forward their AW.169. A razor-thin straight wing carried the engines in nacelles – one Gyron Junior on each side – with a rocket booster under the long narrow fuselage. Two missiles were carried, one on each wingtip.
   
  Vickers-Armstrong submitted the Type 559; an unorthodox canard design with a massive chin air intake, split vertically, for two reheated Gyron engines to 1.950k (placed as in the English Electric Lightning, one above the other).  Two Spectre Junior rockets were situated each side of the jets at wing level.  Two Red Hebe or Blue Jay missiles were mounted alongside the upper part of the fuselage between the canard and the mainplane, which had end-plates incorporating twin rudders.
  De Havilland submitted a relatively small design when compared to the giants from Fairey and Saunders-Roe. The DH.117 was to be powered by two Gyron Junior turbojets and a Spectre booster rocket in the tail, with a crew of two seated in tandem. Provision was not made for Red Hebe, the de Havilland team preferring the company's own line of missiles that would culminate in Red Top.
  English Electric submitted a design based on their successful P.1B short-range interceptor that would become the Lightning. The P.8 was larger overall, carried a crew of two, moved the weapons to the wingtips and undercarriage to the fuselage but featured the same vertically-stacked engine and nose intake layout as the Lightning. The radar package was to be the same AI-23 AIRPASS system as the Lightning but with a larger scanner dish to improve detection range. At the time, English Electric engineers were far from convinced of the ability of fighter aircraft to carry both radar- and infra
caption: Hawker P.1103 company schematic drawing
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