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Aviation History
1960
1960 - 0911.PDF
FLIGHT, 1 July 1960 19 Studies in Design AN ANALYSIS OF RECENT PROJECTS AT THE COLLEGE OF AERONAUTICS IN order to provide students taking the normal Diploma Courseat the College of Aeronautics at Cranfield, Beds, with experi-ence in roughing out the basic design of an aeroplane, the Department of Aircraft Design at the College annually concocts an actual design study for students in their second year. Each project is normally the brain-child of A. F. Newell, deputy head of the department, and J. J. Spillman, senior lecturer in the Department of Aerodynamics. Powerplants may be chosen from a variety of advanced studies which are always in hand by the Department of Aircraft Propulsion, and it is usually possible to present the 2nd-year men with a fairly clear-cut basis of a design. No project is ever anybody's full-time job; instead, four or more students work on it for about three months. After the basic configuration has been decided upon, aerodynamic, stability and control problems are settled, using suitable tunnel models, and the loading cases are worked out in detail. Such an exercise is valuable in the extreme; but the increasing complexity of modern aero- planes has been making it progressively less easy to evolve a design which is truly authentic. The position should improve next month when the College commissions its Ferranti Pegasus digital com- puter, with which it will be possible to programme much greater quantities of data. In any case, even though no project is perfectly conceived, these exercises are very valuable in their detail design problems and in forward thinking generally. For these reasons we are glad to publish notes on the last half-dozen. 1955 Photographic reconnaissance High-speed reconnais- sance seemed particularly important in 1955; there was at the time an official specification for such a machine, but the College did not enjoy any collusion with those working on it. It was particularly hoped that the study would unearth many of the problems of making a steel aeroplane. The 1953 project (an inter- cepter reminiscent of the Lightning) had been designed for manu- facture largely from steel sandwich, and this form of construction was again chosen. Discussions were held with Avro, who were then busily engaged with the 720 intercepter and 730 bomber, and joint research was conducted with welding experts of the British Oxygen Company. Finally a system of puddle-welding was arrived at, and this method has been of assistance to Bristol Aircraft on the 188 programme. It was found that the optimum aeroplane for the mission specified would have weighed between 250,000 and 300,0001b, requiring six or eight advanced Olympus or Gyron engines. In order to reduce the magnitude of the project it was decided to impose an arbitrary limit of 100,0001b. This made the design ineffectual as a PR machine (it could not have done the job) but posed the same problems of aerodynamic design and structure. Powerplants were to be two turbojets from the Department of Propulsion, each installed with a variable-area intake, an after- burner and fully variable convergent/divergent nozzle. Using a simplified method, based on Prof Ward's slender-body theory, the aircraft was very neatly area ruled. The slab foreplane was found to confer satisfactory trim and control over the entire speed range, and by employing blowing over the flaps of the mainplane and the trimming elevators of the foreplane the stalling speed at maxi- mum landing weight was held to 114kt. In actual practice the aircraft would not have been able to accommodate the vast aerials demanded by the mission. 1956 Research On this occasion the College decided to design the sort of aeroplane they would themselves most like to have. Essentially it could be regarded as a replacement for the Anson or Dove as a general-purpose machine for research, instruc- tion and transport. The basic configuration was quite cleverly thought out and would have made the aircraft more amenable to such duties than any other aeroplane yet conceived. It was to be capable of carrying six students and a large amount of test equipment to high altitudes at high subsonic Mach numbers. Power was to be provided by a pair of rear-mounted Bristol Siddeley Orpheus; either would have been capable of flying the aircraft alone, so that the other nacelle could have housed a test engine or a powerplant for boundary-layer control. A very clean wing would have been possible; picking up on the rear fuselage frames, and carrying no landing gear apart from small outriggers, it could carry any desired test equipment and could even be exchanged for a different pattern. For classroom purposes the whole fuselage was to be pressurized, and to facilitate the testing of all kinds of radio and radar devices the entire nose, and the skinning of the underside of the fuselage below the pressure hull, was to be of glass fibre. [Continued overleaf 1955 reconnaissance aircraft. Two reheat turbojets. Length. 105ft 6in; maxfuselage diameter, 8ft; aspect ratio (wing and foreplane), 2.5; t/c ratio (wing and foreplane), 5 per cent; leading-edge sweep (wing), 40°; gross weight, 100,0001b;wing loading, 147lb/sq ft; design cruising speed, 1,880kt (about M3.3) at 65,000ft, for 2,500 n.m. range 1956 research aircraft. Two turbojets each of about 4,5001b thrust; or any of avariety of alternative arrangements with approximately the same aggregate thrust for prime propulsion, exclusive of engines under test or used for specialpurposes (such as the supply of compressed air, hot gas or shaft power). Gross weight, 15,0001b; limiting Mach number 0.8 at up to 55,000ft ceiling 1957 transatlantic airliner. Four turbojets each of about 20,0001b thrust. Grossweight, 320,0001b. Aircraft designed to transport 200 passengers and 7,0001b of freight (in underfloor bays of much greater capacity, assuming typical densities)over non-stop transatlantic stages, cruising at 475kt (547 m.p.h. or M0.825) oooooooooooooooooooooooooooo jooooooooooart CVfliV
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