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Aviation History
1957
1957 - 1065.PDF
"Flight" photographs The French Veronique sounding rocket and (right) a large liquid-propellant combustion chamber by R.A.E. Farnborough. necessary to provide lift towards the Earth's surface. As the speedfell below 5 miles/sec the glider would have to do a roll to keep it from falling on the Earth, since the centrifugal force would thenno longer exceed gravity. By using sharp leading and trailing edges on a small-aspect-ratiowing, the induced drag could be kept high and the heating due to the airstream could be confined to the surface of the wing whichfaced forward: this surface would be designed to melt or bum away without causing extensive failure of the vehicle. The othersurface would have mounted on it the life compartment and equipment, and it would be protected from kinetic heating bythe presence of an absolute vacuum, caused by the flow round the edges of the wing not being able to expand into all the availablespace, as in the limiting case in the classical Prandtl-Meyer expan- sion. The vehicle would be spin-stabilized to avoid the necessityfor a tail system exposed to the airstream. [Its unusual shape and attitude are shown in Fig. 3.]Other aspects of re-entry were covered by papers by DR. N. C. FREEMAN of the N.P.L., Teddington, who put forward a theoryregarding the non-equilibrium behaviour of a dissociating gas when passing through a disturbance such as a shock-wave, and byDR. P. MURRAY of A.E.R.E., Harwell, who spoke of the choice of materials for vehicle outer surfaces, proposing the use of insulatingslab materials outside the vehicle proper, which would then have to be protected against thermal shock and meteoric abrasion by athin, hard skin, either of a metal such as molybdenum or of fused silica. Propulsion and structural design of rocket vehicles in the fairlynear future formed the subjects of papers by PROF. A. D. BAXTERof the College of Aeronautics and by MR. K. J. BOSSART of Convair-Astronautics in the U.S.A. Prof. Baxter's paper formed a com- prehensive review of the problems involved in getting betterperformance and propellants for rockets, and the choice of numbers of stages and engine size, as well as the need for optimizingpropellant mixture ratios, propelling nozzle dimensions and shapes, and of adjusting the direction, velocity and acceleration of thevehicle by controls on the engine rather than by aerodynamic means. MR. BOSSART came to the conclusion that some of the larger Fig. 3. Suggested design of vehicle for re-entry into the atmosphere, with heating effects confined to one side (veh-ities re- lative to vehicle moving from right to left). (Hilton.) \ \ \ V N >»V \ \ \ NX 1 \1 \ ABSOLUTE \ •« VACUUM \ M=OO \ \\\\\N>V vehicles now being built might not be far removed from theultimate size, for he suggested in his paper that 50 to 100 tons might well be the most efficient take-off weight from the pointof view of operating economy. If it were required to put a large satellite into an orbit, this could be done by sending up severalvehicles and joining them together in the orbit, perhaps for an interplanetary voyage.The place of Man in an alien environment was discussed from two aspects by speakers from the U.S.A.F. DR. H. G. CLAMMAN,of the School of Aviation Medicine, spoke about the problems of respiratory metabolism in sealed cabins, and pointed out that itwas desirable to achieve a balance in the cabin atmosphere for carbon dioxide rather than for oxygen, since, if we were consider-ing regeneration of the atmosphere by the use of algae, it was not possible to remove all the CO2 without steadily increasing theoxygen content, although the latter would be quite beneficial. If algae were used, as they might have to be on a voyage ofseveral months or years, the problem would arise of keeping the algae actively converting CO2 into oxygen: this could only be doneif the algae concentration were kept at a constant and fairly low level in the tanks, so that the light required for photosynthesiscould be effective. This would mean disposing of the surplus algae, and this could only be done by using them as food for thecrew. Although algae contained protein to the extent of 50 per cent by dry weight, it might be difficult to maintain a tasty cuisine.LT. COL. J. P. HENRY, of the European Office of Air Research and Development Command, spoke about the mental disturbanceswhich might be encountered when human beings were exposed to a state of isolation with negligible mental stimulus, such asmight be found in a space vehicle or a satellite. Experiments in Canada had shown that when healthy youngmen were kept in bed with their vision impaired by the use of frosted-glass goggles, their tactile senses frustrated by cottongloves, and their hearing masked by a steady humming noise, all the subjects began to show symptoms of abnormality, perhaps ina few hours. They got easily angered or depressed, could not think systematically or productively, and had mental blanks: theysuffered from hallucinations, which might start with dots of light in simple patterns and get more complicated, until their visionappeared to be full of little men or scenes from a film. If the subjects were placed in a tank of water in immersion suitsso as to give an effect of zero gravity, the symptoms would be worse and set in more quickly. A notable feature was the ten-dency for the images to swim or tilt in a nauseating manner. States such as these might be found in a satellite crew, particu-larly if there were little to do; but if plenty of meaningful occupa- tion were available, together with some slight contact with afamiliar environment, the very real danger might be overcome. The final and most forward-looking paper of the symposiumwas given by DR. L. R. SHEPHERD of A.E.R.E., Harwell. Dr.Shepherd, who is president of the International Astronautical Federation, dealt with the requirements of propulsion systems forsuch tasks as making an escape rocket (in a parabolic orbit), a one-way lunar vehicle, or a returning manned lunar vehicle. Hesaid that the first two tasks might be accomplished with chemical propellants, such as fluorine with hydrogen or hydrazine, but forthe return lunar trip the take-off weight might approach 100,000 tons, at a cost of say £10' or £10', which would be prohibitive.He then went on to discuss the application of nuclear energy to rocket propulsion, by heating a working fluid (hydrogen) by pass-ing it through a reactor which might be in the form of beds of small spheres or porous layers. Dr. Irene Sanger-Bredt had com-puted the performance of hydrogen as a propellant up to a tempera- ture of 10,000°K, showing that at no more than 3,000°K anexhaust velocity of nearly 10,000 metres/sec (specific impulse of about 1,000 sec) might be achieved.Alternatively, particularly for a journey which began from a satellite orbit, electrical methods of accelerating the working fluidcould be used. Hydrogen could be passed through an intense electric arc and then expanded through a nozzle; or a fully ionizedplasma, such as that of sodium, could be passed through an electro- magnetic pump similar to the type used for liquid metals in nuclearreactor engineering, and so accelerated directly. The plasma would EARTH
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