A Nuclear Thermionic-Ionic Propulsion System
- Paper ID
IAF-60-07
- author
- company
Lockheed Aircraft Corporation
- country
U.S.A.
- year
1960
- abstract
In case of a Keplerian motion between two fixed points, the initial velocity is shown to have the same magnitudes of radial and chordal (i.e. parallel to the chord of the trajectory between the fixed points) components as the corresponding final velocity. Further, the product of these component magnitudes is shown to depend on the positions of initial and final point, but not on the choice of trajectory between these points. Use of these simple terminal criteria is illustrated by examples. Among these is the difficult problem of optimal two-impuls transfer between given coplanar orbits, i.e. how to determine the transfer which requires the least sum of Velocity increments at the point of departure on the original orbit and point of arrival on the orbit to be entered. Such increments are easily expressed by chordal and radial components of terminal transfer velocity, the position vectors of the point of departure and point of arrival and the orbital velocities at the same points. Each local optimal transfer is determined by the solution of an equation of the eleventh degree in either the chordal or radial component of terminal transfer velocity. Provided the axes of the given orbits are not coinciding, a doubly cotangential transfer may be optimal only if the distances from the Gravitational Center to the point of departure and the point of arrival are the same. For the determination of the time of flight between fixed points, a convenient set of formulae is given in an appendix.