How far the velocity tilts away from the local horizontal (Curtis section 2.4, pages 73-74, figure 2.12).
Definition
- Flight-path angle : the angle from the local horizontal to the velocity vector
- local horizontal = perpendicular to in the orbital plane, i.e. along the transverse velocity
- Ratio of radial to transverse velocity:
Flight-Path Angle
- and in terms of are derived in Velocity in Perifocal Coordinates
Behavior Around the Orbit
- Plot of vs true anomaly for :
- (circle): everywhere
- at perigee () and apogee () for every
- (climbing) from perigee to apogee, (descending) from apogee back to perigee
- Larger larger peak angle (about for ), reached closer to apogee