Lunar Landing Research Vehicle - Control System

Control System

The electronic control system for the Lunar Landing Training Vehicle was developed for NASA by Bell Aerosystems, Inc. which had engineering facilities located in Niagara Falls, New York. The LLTV was a second generation vehicle, after the Lunar Landing Research Vehicle, used by NASA Apollo Program astronauts to develop piloting skills. The LLTV provided Apollo program commanders the opportunity to experience the flight characteristics associated with the 1/6 gravity conditions on the moon. The first LLTV vehicle was assembled at Ellington Airforce Base in Houston, Texas in 1967. A total of 3 LLTV vehicles were eventually delivered to Ellington AFB. The last remaining of the three LLTV vehicles is on display at the Johnson Spacecraft Center in Houston, Texas.

The electronic control system was designed with redundant channels that used 2 of 2 logic. The outputs of each primary channel were compared on a continuous basis. If a fault was detected in the primary control system, then control was automatically switched to an identical backup channel and the pilot immediately took measures to bring the vehicle to the ground. All the controls were analog circuits utilizing Burr-Brown transistor amplifier modules and other analog components. Unlike modern digital control circuits, in 1967 the technology available was limited to discrete transistors.