STUDY OF A GUIDANCE SCHEME USING APPROXIMATE SOLUTIONS OF TRAJECTORY EQUATIONS TO CONTROL THE AERODYNAMIC SKIP FLIGHT OF A REENTRY VEHICLE

摘要

Approximate closed-form solutions to the reentry equations are developed by-assuming that the difference between the centrifugal and gravitational accelerations is negligible. The approximate solutions are valid in the exit-velocity range between approximately 23,000 and 26,000 feet per second. A numerical com¬parison is made between the approximate and exact solutions for six typical tra¬jectories. The results indicate good agreement with complete convergence occur¬ring at the skipout condition within a reasonable flight corridor. Approximate explicit equations governing coasting flight after a skip maneuver are also devel-oped and compared with the exact solutions. A guidance scheme employing these equations is described and results are presented from a two-dimensional digital-computer simulation of this scheme. Emphasis is placed on simplicity and speed of computation. The results indicate satisfactory control to exit from the atmos¬phere over ranges from approximately 70° to 200° about the center of the earth.