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Aviation History
1963
1963 - 1816.PDF
FLIGHT International, 10 October 1963 for example: tank insulation, specialised field testing installations, hydrogen vent gas disposal systems, and tank pressurization systems. These problems are being solved today. Use of future propulsion systems will involve the solution of similar problems. SATELLITE ATTITUDE CONTROL Design of a Gas Jet Attitude Control Sytem for use in Satellites, by A. P. MacLaren (Royal Aircraft Establishment) A design study was carried out to determine the feasibility of a satellite attitude control system in which control torques are obtained from propane gas stored as a liquid. Originally the study was directed towards the design of an attitude control system for an astronomical satellite, which was required to be stabilized to an accuracy of one minute of arc using angular error information from star sensors. The type of control system discussed can, however, be used equally well to fulfil other requirements. For the astronomical satellite the basic design philosophy was to keep the system as simple, reliable and light in weight as possible. To this end it was considered desirable to use a gas jet system of the "on-off" or "bang-bang dead space" type and to avoid using coarse and fine systems, i.e., high and low thrust jets or a combined reaction wheel gas jet system. It was also considered desirable to avoid if possible the continuous use of rate gyroscopes on account of their power consumption and potential unreliability. The paper describes the astronomical satellite and goes on to compare two systems, one of which is stabilized by a phase advance network operating on the star sensor error signal and the other by means of an on-off negative feedback signal, synchronized with dsmanded thrust, which is passed through a passive lag network. In the absence of external disturbing torque this is approximately equivalent to angular rate feedback. The latter sytem is found to be much the better of the two from the point of view of gas con sumption as it can provide very-short-thrust pulses and hence a long period limit cycle, and avoids amplification of sensor noise. EXTENDING BOOMS The Use of Extendable Booms for Space Aerials and for Satellite Attitude Control, by H. R. Warren Hawker Siddeley Aviation) This paper describes a family of extendable aerials and bpoms which are becoming widely used in a variety of space applications in the United States and Canada. With these devices, an extremely long tubular element can be stored in the compact envelope of a satellite for launch and then, once in orbit, can be extended to any desired length to serve as a dipole antenna. The ability to adjust length in orbit enables the aerial to be "tuned" to various frequencies or, as in the case of a design for the Gemini capsule, to be retracted entirely for re-entry. A second application for the device is to form long booms which provide gravity-gradient attitude control of a satellite. After a review of the theory of gravity gradient stabilization, the first practical demonstration of this method of control is described with the unit carried in the Applied Physics Laboratory Traac satellite. Configurations for use in the Transit 5 and Arents satellites are also shown. Another application is a boom to extend an instrument to a location remote from the main body of a spacecraft, such as the magnetometer boom designed for the JPL Mariner craft. Possible future applications of these devices include grappling booms for orbiting manned space stations and retractable legs for vehicles landing on the Moon. PORTABLE CONDITIONING SET The Design of a Personal Portable Conditioning Set for Moon-based Operations, by P- W. Fitt and B. Corrigan (Normalair Ltd) The authors review the essential requirements of a portable conditioning set capable ot supporting a worker on the Moon, and discuss the alternative Principles on which such an item of equipment could operate. Selecting the more promising of these approaches they then describe alternative designs and analyse the merits of each. The following are described in detail:— (a) A set using liquid oxygen as the coolant and source of energy f or the circulation of the ventilating air. (o) A set utilizing the latent heat of water for coolant purposes ^vith an electrically powered air circulating system and a separate °xygen supply for breathing. (c) A set which is designed specifically for use with the new water- cooled suit concept utilizing oxygen for breathing and minimum ventilation requirements. 625 kfcl ASTRONOMICAL^ TELESCOPE STAR LOCK TELESCOPES SOLAR CELL PADDLES GUIDANCE AND CONTROL COMPARTMENT Above, simplified sketch of the astronomical satellite mentioned in the paper by Mr A. P. MacLaren of RAE // DETACHABLE //^-COWLINGS FOLDED SOLAR PADDLE X RAY SENSOR SHADED AREA REPRESENTS PART OF SATELLITE WITH FIXED ATTITUDE IN SPACE TELEMETRY AERIALS EXTENDED SOLAR PADDLE SUN'S DIRECTION WHEN IN ORBIT Above and below, further details of the RAE astronomical satellite project designed for stellar spectroscopy in the ultra-violet region 4ft3in INSIDE DIA ASTRONOMICAL- TELESCOPE , / \PROPANE \\ TANK SPECTROSCOPE FINE GUIDING MIRROR -BEARINGS BEARINGS -STABLE k. COMMAND LINK AERIALS ^ tj|| TABLE ^ r^U STAR LOCK TELESCOPES TELEMETRY AERIALS TELEMETRY AND CHEMICAL BATTERIES DOWN RANGE DIRECTION AT LAUNCH
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