Analog Computer Solution of the Orbital Flight Equations

Abstract

A modified flight-path axis system is introduced to simplify computer mechanization of the orbital flight equations. Complete six degree-of-freedom equa tions are presented, including aerodynamic, power- plant, and control forces. Electronic differential analyzer mechanization of these equations in both real and fast time is described, including a novel technique for division which preserves favorable multiplier scaling. Specific machine results are presented which demonstrate accurate solution of close-satellite tra jectories, including re-entry from satellite altitudes to sea level. With no change in circuit or scaling the same computer mechanization yields zero-drag orbits which close within several hundred feet of altitude.