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Aviation History
1957
1957 - 1802.PDF
892FLIGHT, 6 December1957 RANGE RANGE RANGE Fig. 3 (left). Trajectory for a ground-launched rocket-propelled boost-glide missile. Fuel is exhausted at the point marked (A). Fig. 4 (centre). Trajectory for an air-launched rocket-propelled boost-cruise missile. Fig. 5 (right). Climbs tor air-launched turbojet (A) and ramjet (B) missiles. STAND-OFF BOMBS... rocket-powered missiles detailed optimization of the climb leadsto achievement of maximum range. Air-breathing engines have an upper limit of speed at which theycan be used. A Mach number of approximately 3 is the ultimate limit for turbojets, and a Mach number of about 5 for ramjets. Itis, therefore, clear that trajectories for missiles with air-breathing engines must be of the boost-cruise type. The cruise is flown atthe maximum L/D, and, because of the variation of thrust with altitude, engine size and wing area must be matched to the requiredperformance. In the case of the ramjet it is desirable to fit larger engines and to cruise with reduced thrust. The effect of the extraengine weight is more than compensated by the reduction in specific fuel-consumption so obtained. The optimum cruise is,therefore, flown at maximum L/D -r s.f.c. Ground-launched turbojet and ramjet missiles must be boostedtransonically to a speed at which their own engines can take over. They then accelerate in a gentle climb until the cruising altitude isreached. For air-launched turbojet and ramjet missiles all-up weight isvery important, because of the limitations of the carrying aircraft. In order to retain as much missile fuel as possible for the cruise,it is desirable to reduce the size of the rocket boost to a minimum, particularly if the booster is not jettisoned. A turbojet missile canbe flown without a rocket, but in the ramjet missile a rocket boost is essential, since the ramjet will not give thrust until the missileis flying supersonically. Normally, after a period of initial accelera- tion, the missile powered by an air-breathing engine acceleratesin a gentle climb until its cruise altitude is reached. Speed and altitude must be matched during this climb to keep the engineinternal pressure to a minimum, thus permitting the use of a lightweight engine. For a turbojet missile the initial period ofacceleration can take place in nearly horizontal flight, but for a ramjet missile it is desirable to accelerate in a dive; potential energyis changed into kinetic energy and the speed at which the ramjet can take over is thus achieved as soon as possible. The ramjet fuelused in climbing to regain altitude is small compared with the rocket fuel saved by this manoeuvre. Climbs for turbojet andramjet missiles are compared in Fig. 5. It is clear from the foregoing that the choice of powerplant fora flying bomb depends upon the range and speed that is required. The general shape of trajectory can then be determined, butdetailed optimization is very important. ROCKETS FOR RESEARCH (continued from page 888) (4) To determine the undisturbed ambient pressure at variousaltitudes: three Pirani pressure gauges carried in the rocket cone, one measuring ram pressures at the tip, and the other two measuring conewall pressures. (An R.A.E. investigation.) France and Japan. French work on sounding rockets hasincluded the massive Veronique, a development of the German V-2 with a payload of 130 lb. This rocket has attained an altitudeof 84 miles, and incorporates 20-channel telemetry. Work on Veronique, which has recently been displayed with modified finsurfaces, is taking place at the Colomb Bechar research centre. In Japan, the I.G.Y. programme includes two sounding-rocketprojects designated Kappa and Sigma. The former involves a multi- stage, solid-propellant rocket designed to carry a 15 lb payload to80 miles; and the latter is a rockoon system with a small rocket (total weight about 25 lb) having a peak altitude of 55-65 miles.Twenty Kappa rockets are being fired from the Akita test centre of Tokyo University in northern Japan, and will measure airpressure, solar radiation, ion density, cosmic rays, temperatures and winds. The Soviet Union. Russian efforts in the field of high-altituderesearch have already produced the world's first two artificial satellites. This tremendous achievement, and the new knowledgeit provides, must be at once the most important and the most interesting facet of Russian research; it is supported, nevertheless,by a large-scale programme of sounding-rocket measurements. Referring to Soviet I.GY. participation, a Moscow scientist saidrecently that over 100 research rockets were to be launched to , 50-125 miles from three sites. The first sputnik launched on October 4, is a 23-inch sphereweighing 184 lb. It carries two radio transmitters (20.005 and 40.002 Mc/s) which continued to operate for three weeks, andwhich were stated by Pravda to have transmitted (by variations in frequency and timing) measurements such as temperatures. Concerning the experimental data which artificial satellites in general would provide, Pravda noted these points:"As regards cosmic rays, the programme provides for the study of the relative content of various nuclei in primary cosmic radiation. In par-ticular, scientists are to determine the relative content of the nuclei of lithium, beryllium and boron, and also high-charge nuclei. . . ."The Sun's short-wave radiation has not so far been studied because of its absorption by the atmosphere. The satellite, revolving at a greatheight, will make it possible to study the ultra-violet and X-ray sectors of the solar spectrum and to determine the variations in the intensity ofsolar radiation. This will be most important, for it is now believed that it is the Sun's short-wave radiation that causes the ionisation of theupper Layers of the atmosphere. Since the Sun's short-wave radiation is caused by the corona, the data received will provide new informationabout the structure of the corona. "In addition to the Sun's short-wave radiation, the processes in theupper layers of the atmosphere are greatly influenced by the Sun's corpuscular radiation. Because of this, it is most important to establishthe nature of the corpuscular radiation, its intensity and the power spectrum of the particles shot out by the Sun and to establish the roleof the Sun's corpuscular radiation in the auroral displays. . . . "Of considerable interest will be the study of electrostatic fields atgreat heights (in the region of 600 miles). The satellite will also help to establish whether the Earth with its atmosphere forms a charged or aneutral system. . . ." The second sputnik, launched on November 3, was stated to becarrying a payload (including dog) of 1,120 lb and to have an initial apogee (furthest distance from the Earth during orbit) of about1,055 miles. Its radio and telemetry equipment ceased to function after one week. A published diagram showed this satellite not tobe spherical, but to consist of the last stage of a rocket. The dia- gram, together with additional technical details of the satellite,was printed in Flight of November 22. Certainly the most generally interesting, and possibly the mostsignificant, aspect of the second satellite, was the fact that it carried a living animal inside it. In the dog's hermetically sealed chamberwas measuring equipment to record the animal's physiological functions and also equipment for air regeneration and feeding.The pulse-beat and breathing of the dog, together with its arterial blood-pressure and cardial biopotentials and the temperature andpressure in the chamber, were recorded and telemetered to the ground stations. In order to regenerate the air inside the chamber and maintainthe required gas composition, highly active chemical compounds were employed, giving off the necessary amount of oxygen forinhalation, and absorbing carbon dioxide and the surplus vapour. Owing to the absence of air convection in conditions of zero gravity,an arrangement for forced ventilation was installed. Although short-duration flights up to 120 miles had previouslybeen made by animals in upper-air rockets launched from the U.S.A., the dog Laika's journey in Sputnik IT was the first inwhich it was possible to study the protracted effects of zero gravity on a living organism. An intriguing postscript to the Sputnik II reports was givenin Moscow on November 21 by Professor Vitaly Ginzburg, who said that observation of satellite orbits might provide verificationfor certain parts of Einstein's general theory of relativity. Par- ticular effects in this theory which could be checked included thelag in cosmic time behind Earth time. This is the effect which is claimed to produce the anomalousbehaviour often referred to in science-fiction stories and described by Ginzburg as follows: "The difference in the time readings on the Earth and on thesatellite will be very small, amounting to no more than sorrte hundredths of a second per year. Considering the universe witnits cosmic speeds as a whole, however, the effect will add up 'J> many months and even years. The passengers of some futuephoton rocket leaving the Earth on a space trip of several years — according to their scale of things—will return to Earth in a mat;, rof dozens of terrestial years. Such a trip is largely in the realm 't fantasy, but is perfectly feasible in principle." , It is in these directions—-tomorrow's directions—that today srockets for research are pointing. K.. T. O.
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