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Aviation History
1951
1951 - 0853.PDF
Fig-. 6. The North American NATIV was designed for aerodynamic research and the development of control systems.t it has reached an altitude of over ten miles. Evolution of the Guided Missile aircraft, and it is possible for control to be handed on from one post to another during the missile's flight. The Wasserfall (Fig. 4), for which the Beam-Rider system of guidance was being developed in Germany, appears to have been remarkably successful in its early trials as an inherently stabilized missile. In many respects a small-scale version of the V.2 rocket, and powered by a B.M.W. bi-prbpellant motor with gyro- controlled exhaust vanes, it had cruciform wings of bi-convex section which, with very large fins and control surfaces, afforded perfect stability throughout its entire flight from subsonic to supersonic velocities. With a length of 25.6ft and weighing four tons at take-off, the missile was designed to attack at altitudes between three and nine miles and had a range of operation up to 30 miles. It is in many ways surprising that production of the Wasserfall was not taken up in Britain when the guided-missile programme was first laid down in 1945, if only to give our technicians "something to play with" in the shape of a successful missile. With such a primary vehicle, they ceuld have carried out all their basic research on stability, inherent control, booster techniques, remote guidance, etc., at an early stage, besides obtaining expenence in the handling and servicing of a practical supersonic rocket—a rocket, moreover, that could not otherwise be had but for years of labour and vast expenditure. Failure to evaluate and exploit the German research effort in this practical sense has undoubtedly made the British missile programme both • laborious and uneconomic. The development of ground-to-air missiles in the United States has progressed steadily since work was begun at the California Institute of Technology in 1944. In 1945 emerged the W.A.C. Corpora], a rocket designed for high-altitude research but which was also regarded as the potential basis for an air defence missile. Other missiles under various stages of development as Fig. 7. An early missile in the Boeing GAPA programme being made ready in its launching tower in the heart of the Great Salt Desert. Utah. FLIGHT, 4 May 1951536 experimental A.A. weapons or troop-training vehicles, are the Boeing GAPA, the Fairchild Lark and the North American NATIV. The Lark (Fig. 5) was the outcome of research by the Guided Missiles Division of the Fairchild Engine and Airplane Corpora*, tion. It is now in quantity production for the United States NavyJ" being employed both as a launching-crew training-missile and as a flight test vehicle to prove a Fairchild developed target-homing system. From a cursory examination of the project, it appears that development problems have been reduced to a minimum by means of straightforward design. There is nothing about the missile that could be called spectacular, but from the large number of successful flights (over 100 test vehicles have been fired) one can assume it achieves a high standard of reliability. With a length of 14ft sin, the hull is cylindrical, with a subsonic streamlined nosing and a straight-tapered tail section. Two horizontal and two vertical wings are fitted mid-way along the hull, with four tail-vanes located quadrantally to the wings at the rear end. All the aerodynamic surfaces are rectangular and each carries trailing-edge control surfaces. On the wings, the-control surfaces provide directional steering; on the tail-vanes, they control the flight attitude and serve as trimmers. Extensible ailerons, normally retracted within the vertical wings, snap out on either side to check any tendency of the missile to roll. A launching booster, comprising two standard Aerojet JATO units inside a large box fin, is attached at the tail. Various materials are used in the construction. The hull is made up of five sections of light alloy, using normal aircraft monocoque practice, and two tank sections of stainless steel. The nose dome, which incorporates a semi-active target-seeking device, is of Fiberglas, a thermo-setting plastic. The wings are single aluminium extrusions, whilst the tail-vanes are moulded from Fiberglas sandwich material in which the receiving antenna: are inherently bonded. • The propulsion unit, manufactured by Reaction Motors Inc., is a bi-fuel two-motor system using red fuming nitric acid and aniline. After the booster jettisons, only the main "sustaining" motor operates, the "auxiliary" motor being called upon to supply additional thrust solely when executing manoeuvres. The fuel and oxidant are pressure-fed to the motors by the compressed-air inflation of plastic bags within the tanks. Perhaps the neatest feature is the method of installing electronic equipment. Each unit assembly of the guidance and telemetering systems is bench-wired and is placed in a quartered or halved container with a single external connector. Inside the missile, bulkheads are spaced to receive these containers, each bay having the corresponding connection point linking the equipment to its appropriate service. Thus, should pre-flight testing show up a fault in any particular circuit, the essential components can be disconnected and instantly replaced as a unit. Before assembly, ail components are subjected to a 5Og drop-test and a vibration test at 1,200 cycles per second. The Lark has been produced under a Navy contract originating in 1945, and of the large numbers now becoming available, some will go to the U.S.A.F. for training purposes as well as to Naval test centres.Of the other missiles, the NATIV (Fig. 6) is a test vehicle for aerodynamic research, control-system development, and the training of launching crews. Only 13ft long, with a diameter of i8in, it is fired from a tall metal tower and has reached altitudes above ten miles. The GAPA (Ground-to-Air Pilotless Aircraft) project is really a development programme in which several prototype missiles are featured. Research at Boeing's was begun early in 1945 and the all-rocket powered vehicle originally produced (Fig. 7) has given way to a ram-jet missile with rocket booster. No details of this latter project are available except that the all-up weight is 5,000 lb with a 200-lb warhead, and the flight Mach number is 2.5. Considerable work is being undertaken in the United States by various agencies with ramjet propulsion units, among them Princeton University's Department of Aeronautical Engineering. Fig. 8. The PTV-N-2 Gorgon 4, a pilotless aircraft built by Glenn Martin for the U.S.N. to test ram-jet propulsion units In free controlled flight.
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