Handling Qualities for Pilot Control of Apollo Lunar-Landing Spacecraft

Piloted simulations of the lunar-landing maneuver were conducted at the Manned Space-craft Center to determine control problems and required handling qualities of lunar-landing spacecraft. The studies examined control problems and handling qualities required to com-plete the final approach to landing starting from ranges of 2000 to 3000 ft from the desired landing site. Results of the simulation studies indicated that satisfactory handling qualities could be obtained with control powers of the order of 10 deg/sec2 for the rate command control using proportional firing thrusters, and that control powers of the order of 5 deg/sec2 pro-vided satisfactory handling qualities for the rate command control system employing on-off thruster firing logic. Within a satisfactory range of maximum rate command and control power available, the pilots tolerated equivalent time constants up to 1 sec in the proportional system and equivalent time constants of the order of 3 sec in the on-off thruster logic control system. In addition, the simulation studies showed that the direct on-off logic control sys-tem (no rate feed-back) would probably not provide satisfactory control handling qualities for the lunar landing