FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1957
1957 - 0540.PDF
542 FLIGHT, 26 April 1957 English Electric P.1A Two Armstrong Siddeley Sapphire PROGRESS WITH THE P.I . . . It is unfortunate that, perhaps owing to a misconception of whatit means or mere lack of experience with advanced types of air- craft, the Weapon System Concept is looked upon with some dis-favour in certain British quarters. In the design and development of an operational supersonic aeroplane every factor which canaffect combat perfonnance of the machine must be integrated with every other item at the earliest possible stage of design. EnglishElectric appreciated from the outset that the mere installation of two guns and a gun-sight was incompatible with the achievementof an efficient combat system. Accordingly the whole basis of the programme was enormously broadened to include such diverseaspects as production tooling, tropical and cold-weather operation and field maintenance. Such was the magnitude of the programme that it was decidedto order what, by British standards, was an unprecedented number of prototypes. It was decided that an intermediate developmentdesign, designated P.I A, should account for two complete aircraft and one airframe for static testing, and that a later development,the P.1B, should account for three prototypes and 20 pre-produc- tion aeroplanes. Such a quantity was considered adequate for theimmediate programme of research and development facing the company. It marks a welcome change in thinking, which shouldprevent repetition of the unhappy histories of some earlier R.A.F. fighters. U.S.A.F. programmes have been financed in an even moregrandiose and determined manner; development test flying of the Convair F-102 (.Flight, April 19) was undertaken by 52 aircraft,together with two TF-102 two-seaters, and at any.given time several F-102s were employed on drag measurements alone. Wein Britain simply cannot afford to operate on such a scale. Our 20 extra P.I development aircraft are the most we can deploy tosolve the technical problems ahead. They will not necessarily allow the P.I development cycle to be quicker than that of any earlier fighter; on the contrary, they are needed to get the hugetask done in anything like a reasonable time. While the P.1A was passing through the detail design stage itwas generally accepted that future fighters would be individually so expensive that they would be bought in much smaller numbersthan their predecessors. Moreover, it was generally accepted that there was little point in developing a complicated supersonic aero-plane for the defence of Britain unless that aircraft could operate at night or in bad weather. It is pertinent to record that, contraryto a decision previously taken by the U.S. Air Force, the British Air Staff considered that the full requirements for all-weatherinterception could be met only by a two-seat aeroplane. English Electric felt that, as the ultimate aim was the elimination ofthe human crew entirely, it was logical to minimize the crew as far as possible and make automatic equipment perform all the essen-tial functions of the weapon system. This philosophy fundamentally (and, in general, advantage-ously) affected the size, shape and ability of the aircraft; but it has naturally placed a considerable strain on the very many firmsresponsible for delivering the airborne equipment. When the aircraft was being planned no British accessory supplier had anyreal experience of designing equipment for supersonic aircraft application. From the view-point of temperature, the ruling designcondition was that appropriate to "tropical day at sea level," to which kinetic heating and skin friction in the P.I can add 50 or100 deg C. Full cockpit refrigeration was a requirement from the start, and even the basic structure of the machine had to beunusually carefully designed in order to meet requirements which previously were peculiar to the U.S.A. As already stated, the wing is of a peculiar family which can beconsidered either as a "plank" wing swept back to an angle of 60 deg on the leading edge or as a notched delta. The lattermetaphor is really incorrect, since the P.I retains the conventional horizontal tail surface, with a plan-form very like that of the wing.The vertical tail is almost of delta shape. The wing, which spans 36ft from tip to tip, is evidently anintegral tank, and it must have very thick skins between the spars. Photographs show that the thickness/chord ratio is around five percent, measured parallel to the longitudinal axis of the aircraft. It is worth noting that the aerodynamic chord is considerable—and,in fact, the wing is distributed over an exceptional proportion of the overall length of the aircraft. It thus becomes much less of astumbling-block to the achievement of the optimum axial distribu- tion of cross-sectional area. A diagram published in our issue ofDecember 2, 1955, indicated how this factor has facilitated con- formation to the area rule to minimize transonic drag. Similar considerations resulted in the unfamiliar, but efficient,profile of the fuselage—which we once described as having "all the shapeliness of a suitcase." The considerable length of 52ftreflects the difficulty of accommodating two powerful engines fed from a nose intake, together with a cockpit, armament and alloperational equipment, in a body profile of the correct fineness- ratio. Consequently much of the P.I fuselage is occupied by intakeducting or tail-pipe, although with proper design this should not greatly penalize engine performance. Considerations of e.g. andfuselage depth probably precluded positioning both engines at the rear, so they are longitudinally separated and reached, or removed,through large hatches in the top or bottom of the fuselage. Clearly, both engines cannot drive a single accessory gearbox. All flying controls must be fully powered and irreversible. Therudder is tabless and was originally horn-balanced. The hori- zontal tail comprises low-mounted, swept "slabs" separated by thelower jet-pipe. The ailerons are of very unusual geometry in that, At the Warton butts is WG 763, the second P.I A—note ventral fairing—with Sapphires roaring and solid shot spewing from the two 30mm Aden guns. Well might the onlooker stop his ears; even the helmeted English Electric test pilot in the cockpit must be deafened. I ••2783 n IFICE CO :itu
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
