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Aviation History
1958
1958 - 0226.PDF
236 FLIGHT, 21 February 1958 TOWARDS ASTRONAUTICS Problems of a Significant Transition Period A model of the proposed high-altitude aerodynamic research vehicle described in this article, in position for air-launching from a Vulcan. ROM Aviation to Astronautics" was the title of a lecture given by Mr. J. E. Allen, B.Sc.(Eng.), A.F.R.Ae.S., A.M.I.Mech.E., F.B.I.S., before the Manchester branch of the Royal Aeronautical Society on January 22. Mr. Allen is head of the aerodynamics, projects and assessment department of the A. V. Roe weapons research division at Woodford. The first part of the paper contained a review of current high-altitude aircraft, guided weapons, high-altitude rockets and satellites; the second section was devoted to future design trends and some immediate targets in space-flight. Referring in his historical introduction to the significance of theRussian sputniks, Mr. Allen said that, from its inception, the satellite, unlike the aeroplane, had drawn extensively from thepractical and theoretical knowledge established in other fields. These included electronics, guided missiles, automatic systemsand aeronautics. It was this latter fact which made the present transition period so significant to the science of aeronautics. If noone had prophesied interplanetary flight, it appeared that aero- nautics, for its own reasons, would have had to develop the sametechnologies. In the course of time, however, interplanetary flight would produce its own devices and principles, such as ionic andnuclear powerplants, which might not have any application on this planet. Extracts from the second portion of Mr. Allen'spaper are given below. It is a common observation [the lecturer stated] that no newdevice or invention can nourish in the world before its time. The many branches of technology associated with aeronautics havegradually developed in the last 15 years and the advent of space flight may be regarded as a logical outcome of this work. Rocket propulsion is the only means yet available for escapingthe gravity of the earth. Many billions of pounds have been spent in research and development of the large liquid-rocket motors inconnection with the V.2 and later ICBM ballistic rockets. The performance of the latter is of the same order as that needed forsatellite flights of smaller payloads. A two-stage hypersonic rocket being prepared for air-launched flight test from a B-57A in the propulsion-research programme of the N.A.C.A.'s Lewis Laboratory. Guidance for aircraft and missiles has, in automatic inertial andcelestial navigation, deserted purely earth-bound aids to seek the references of inertial space and the stars. The precision of naviga-tion needed for aircraft, missile and elementary space-flight can be attained by comparable instrumental techniques. Associatedwith these guidance developments are those of complex electronic control and computing equipment. The need to cram quarts ofelectronic brains into pint pots of small intercepter missiles has given a remarkable impetus to miniaturization techniques suchas transistors, digital systems and printed circuits. Recent work indicates that there are still many advances to be made along thisroad. In the early days of space-flight, when performance margins are small, miniaturized equipment will pay dividends in extendingphysical experiments to greater distances. In the piston-engined aeroplane, "performance" was dennedquite adequately by level-speed and rate-of-climb values, chang- ing with the introduction of jet aircraft to include zooming effects.Missile trajectories take this a stage further, depending almost completely on complex digital computers for their evaluation. Foradvanced missiles one can no longer consider the earth as flat— a liberty which aeronautics has been able to take for the sake ofmathematical simplicity for over 50 years. For ballistic missiles, satellites and interplanetary flights the flight paths are now calledorbits and will be solved by means of celestial mechanics, estab- lished by astronomers many centuries ago. Already maximumaltitude is called "apogee" and minimum altitude "perigee." There has been a major revolution in aerodynamics since 1940.Until then virtually all aeronautical applications were subsonic and it was obvious that much research was necessary for a betterunderstanding of the theory of lift, drag, propulsion and inter- ference for application with greater certainty in design. Sincethen, aerodynamics has progressed through the transonic and supersonic regions to hypersonics. Mach numbers of 23 havebeen measured in free flight and 50 and 200 (nominal) in the laboratory. We can now truly say that a vast area of aerodynamicshas been tentatively explored, for there is no virtue in hurtling through the atmosphere at speeds exceeding satellite velocity.There is a tremendous amount of research still to be done, but the broad physical characteristics of the different regimes have beenmapped. Consider the stagnation temperature associated with flight atvarious Mach numbers through the atmosphere. Temperatures up to 8,000 deg K will exist behind the strong normal shock wavescreated by a blunt body. As the internal energy of the air in- creases, the higher energy levels (such as vibration, disassociation,electronics and ionization) are excited, resulting in much lower temperatures than those obtained from ideal gas theory. In addition to changes associated with the physics of the air athigh temperatures, certain chemical transformations take place. At room temperature, air consists of approximately 78 per centN2 and 21 per cent O2 (by volume), with traces of other substances such as water vapour and argon. At higher temperatures the aircontains oxygen and nitrogen in both molecular and atomic forms; and nitric oxide, free electrons and ions may also be present. At very high temperatures free electrons are produced andthese, moving in the boundary layer and wake, induce luminous discharges and electro-magnetic effects. Aerodynamics and astro-physics are brought closely together by the science of magneto- hydrodynamics, which deals inter alia with the formation ofsunspots and solar prominences and the creation of radio noise in outer galaxies, and also with the influence of conducting fluids on
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