Effects of Control Power and Inceptor Sensitivity on Lunar Lander Handling Qualities

Abstract

A piloted simulation studied the handling qualities for a precision lunar landing task from final approach to touchdown. A core model of NASA’s Altair Lunar Lander was used to explore the design space around the nominal vehicle configuration; details of the control and propulsion systems not available for that vehicle were derived from Apollo Lunar Module data. The experiment was conducted on a large motion base simulator. Eleven Space Shuttle and Apollo pilot astronauts and one test pilot served as evaluation pilots, providing Cooper-Harper ratings, Task Load Index ratings, Bedford workload ratings and qualitative comments. Following attitude guidance cues, the pilots evaluated control powers ranging from 1.1 to 4.3 deg/s 2 , maximum rate commands from 3 to 20 deg/s, which is equivalent to a range of inceptor sensitivities, and two magnitudes of disturbance moment arising from propellant slosh. The handling qualities were satisfactory for the highest control powers and low inceptor sensitivities, with reduced sensitivity both improving handling qualities and reducing propellant use for a given control power. Pilots used low attitude rates regardless of the maximum rate available or control power. Propellant slosh degraded handling qualities approximately one Cooper-Harper Rating.