Accession Number : AD0770288

Title :   Some Necessary Conditions for Time-Optimal, Fixed-Fuel Transfers Between Coplanar Orbits.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING

Personal Author(s) : Tubbs,Ronald C.

Report Date : MAR 1971

Pagination or Media Count : 71

Abstract : Some necessary conditions in terms of the state and costate variables are derived for time-optimal, thrust-coast-thrust (TCT) trajectories between coplanar, cofocal orbits in an inverse-square gravitational field. Assuming impulsive thrusting, the transfer trajectories are determined by solving a quartic polynomial in the square root of the semi-latus rectum of the transfer orbit. The IBM 7094 digital computer was programmed to solve the polynomial and isolate the root leading to the optimal trajectory. Final mass to initial mass ratios are specified, and initial mass is taken as unity. The necessary conditions are derived using plots of constant mass contours in the transfer angle vs. transfer time plane. The conditions are intended to indicate when the TCT trajectory is not optimal and should be replaced by another type of trajectory, such as coast-thrust-coast-thrust (CTCT) or thrust-coast-thrust-coast (TCTC). (Modified author abstract)

Descriptors :   *Transfer trajectories, *Controllable thrust rocket engines, Computer programs, Circular orbits, Elliptical orbit trajectories, Partial differential equations, Numerical integration, Gravity, Theses

Subject Categories : Spacecraft Trajectories and Reentry

Distribution Statement : APPROVED FOR PUBLIC RELEASE