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Aviation History
1951
1951 - 1495.PDF
142 FLIGHT, 3 August 1951 EVOLUTION OF THE GUIDED MISSILE . joined. If necessary (assuming, of course, that zero "g" has noadverse physiological effect), it would be possible for the crew to work outside the vehicles and to move themselves around theregion of the space-ships with the aid of miniature, hand-operated rocket units. In this condition where material is "weightless,"considerable feats of engineering assembly could be achieved by one or two men working for quite short periods. The uniqueproperties of the sub-orbit are not widely appreciated and although their consideration, at first sight, may appear to savour of imagina-tive fiction, they are nevertheless based on well-established principles. The essential point to grasp is that rockets, materialsand men, having become "satellites" of the Earth, are held in balance between the inward pull of gravity and centrifugal force;the conditions of "fall," therefore, no longer exist and although all are travelling with an orbital speed of more than 18,000 m.p.h.,in terms of one another they are motionless. With orbital technique, there are four basic types of rocket, eachbeing designed specifically for one role of operation which is complementary to the other three. (Fig. 31). The Types A and Boperate together as a composite vehicle; the former acts as the propulsion component for the Type B and remains in the terminalorbit of the destination planet whilst the smaller rocket descends to the surface. Fabrication of the orbital space-vehicle (Type A) would proceedfrom the establishment in a circumterrestrial close-orbit of a nucleus-powered rocket, similar in conception to the vehicle ofFig. 30 but omitting expendable tanks, the three-step "chemical" rocket and the crew chamber; these will be replaced by fixedcylindrical tanks. Along the outsides of the vehicle will be carried the light girders and other materials which will later beused in the construction of the landing rocket (Type B) in the terminal orbit. Once the Type A is established in the sub-orbit, chemically-powered step rockets carrying materials and personnel will climb from the earth and rendezvous in the vicinity of operations. Forthe most part, these will be guided missiles which are wholly expendable, the final steps (Type C) being designed for use by theconstruction crew as material for the composite vehicle. For example, the pressurized tank sections of expendable rockets canbe used directly as the tubular structure connecting the " atom rocket" to the Type B vehicle. The remainder will be winged rockets (Type D) capable of being refuelled from expendable"tanker" rockets and returning to earth with members of the construction crew. The design of the landing rocket (Type B) would be determinedby the gravitational field strength of the destination planet, and whether it was winged or not would depend on the presence of anatmosphere having a sufficient density to justify the use of aero- dynamic braking. If there is negligible atmosphere—as in the caseof the Moon—the rocket will descend vertically, using reverse rocket braking in conjunction with a.radio-altimeter and landinglegs. Changes in course and trim will be made by rocket units situated around the hull, and stability during the final approach tolanding would be maintained by gyro-controlled vanes impinging in the exhaust; these vanes will keep the vehicle falling verticallywhilst its downward-firing jets act as a brake until, at a small distance from the surface, the moon's gravitational pull is counter-acted and the landing legs spread out to take the force of impact. A film of a V-2 taking off, run in reverse, would in fact give afairly accurate representation of the landing technique envisaged. The Type B rocket will, of course, be useless for anything butlanding on an airless body and, as a result, might be left orbiting the Moon while the crew return in the Type A to the original terminalorbit about the Earth; there, winged "ferry" rockets of Type D, using both rocket and aerodynamic braking, would enable themto return to the surface. A later expedition to the Moon might then use the landing rocket after refuelling it from a reserve ofpropellant carried out for that purpose. Whereas all the previous investigators have considered thespace-ship as expendable, orbital technique will permit the major vehicles engaged in the project to be used repeatedly. Itwould be rash, however, to suggest that the scheme is the panacea for all our troubles, which is evident in the fact that to place a mere350 lb of useful pay-load in a close-orbit with available propellants, will require a vehicle of almost 80 tons initial mass.* When weconsider bringing not pounds of instruments but tons of propellant into the sub-orbit, the problems which still confront us in theinterplanetary project are thrown into bold relief. For the refuelling rocket, one would probably aim at a two- or three-stepvehicle of 200 to 300 tons initial mass for a payload of 2 tons. With these figures in mind, we see that the initial interplanetaryventure would be made with greater overall effort, greater technical complexity, and the expenditure of more propellant than if theproject could be sponsored as a "one-shot" step rocket. But because a direct flight to our nearest planetary neighbour cannot *See "Conception of an Instrument-Carrying Orbital Rocket," by A. M.Kunesch, B.I. S. Journal, May, 1951. WINCED FERRY ROCKET (Type D (Final step of piloted vehicle for transporting personnel to and from terminal orbit) EXPENDABLE FREIGHTER ROCKET (Type c' (Final step of pilotless vehicle for transporting materials, supplies and propelant) Pr«iswiz«d crew chamber of landing rocket Propellant tanks Gyro- controlled exhaust vanes \ Sectlonj^bf connectlnq v3ibe obtained from expendable freimtefroc ANDINC ROCKET Type B") chemically fuelledexpendable rockets Nuciear reactor (t type J and pump u on 'Atomic arrival ot rocket' terminal J orbit Fig. 31. Illustrating orbital technique. Instead of landing the entire spaceship, a secondary rocket will descend to the surface whilst the major vehicle (which contains the flight propulsion motors and "return propellant") remains in a sub-orbit of the destination planet. The project is begun in a circumterrestrial orbit 500 miles from the surface and involves rockets of four types:— Type A: Initially a ground-launched nuclear-powered rocket which is adapted in the terminal orbit to suit its specialized role as the orbital space-rehicle. Type B: The secondary landing rocket, built in the terminal orbit from prefabricated sections brought out by the Type A vehicle and small expendable rockets of Type C. Type C: Expendable rockets for bringing material and propellant to the terminal orbit. Type D: Winged "ferry" rockets for transporting per- sonnel between the Earth and the terminal orbit. The Types C and 0 depicted are the final stages of 2- or 3-step rockets with take-off masses of between 200 and 300 tons: to imp™** the economics of the operation, every attempt would be made to recover the initial steps for re-use, possibly °Y means of "ribbon" parachutes, with a minimum of thrust braking. Alternatively, they might be fitted with wings which act in the line of flight during ascent but convert the empty steps into gliders after separation.
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