SURVEY OF ALTITUDE-MEASURING METHODS FOR THE VERTICAL SEPARATION OF AIRCRAFT

摘要

An evaluation has been made of a number of altitude-measuring methods based on the measurement of such quantities as gravity, acceleration, atmospheric pressure and density, cosmic-ray and magnetic-field intensities, capacitance, and radio and sound-wave propagation.nFrom this evaluation it has been concluded that, for high-speed, high-altitude cruise operation, only the most accurate' of the full-range pressure-measuring instruments, the static-pressure compensator-computer system, meets the ±250-foot system-accuracy requirement for JL,000-foot separations for the complete altitude range up to 70,000 feet. If selected units of this electromechanical computer are incorporated in a system utilizing the best of the service-type static-pressure installations, and if both of these components are calibrated by the most accurate of the presently available techniques, it appears possible to achieve a system accuracy of ±200 feet at an altitude of 70,000 feet. In the event of electrical power failure in the computer system, a full-range mechanical-type altimeter incorporating the precision-type mechanism can provide a satisfactory order of accuracy for standby operation, provided corrections are manually applied for the altimeter-scale and, static-pressure errors.nFrom the standpoint of providing minimum static-pressure errors at supersonic speeds, a minimum effect of angle of attack, and a high order of repeatability of the errors over a long period of time, it is believed that a static-pressure tube located ahead of the most forward part of the airplane will provide the optimum static-pressure installation.nTo achieve the highest order of accuracy with pressure altimetry, it will be advisable to standardize the .apparatus and techniques used for the calibration of the pressure-measuring instruments and the static-pressure installations.