Image Number 4 for United States Patent #5079711.
A variable bandwidth factor KALT is applied in a total energy control system to obtain a reduction in throttle activity while maintaining system stability. The system has a total energy control loop and an energy distribution control loop. In the former, a net thrust command signal T.sub.c is generated to reduce the total energy error to zero. In the latter, an elevator position command signal .delta.e.sub.c is generated to reduce the energy rate distribution error, i.e. correct the distribution of energy between kinetic energy (speed) and potential energy (altitude). The error signal input into each loop has a flight path component and a speed component. The factor KALT is applied to both components of the total energy error to reduce the bandwidth of the total energy control loop with increasing altitude and thereby reduce throttle activity. The factor KALT is also applied to one of the components of the energy distribution error to prioritize reduction of that component to zero by control of elevator position. Preferably, speed control is prioritized, and energy errors are channeled into short term deviations in altitude.