Complete Apollo Block II Pulsed Integrating Pendulous Accelerometer Assembly complete with accelerometer and the suspension electronics, manufactured by the Sperry Gyroscope Company, comprising one unit marked "Apollo Matched Pendulum & Module Assembly, Part No. 108077-2, Pendulum Part No. 108000-2, Module Part No. 105735-4," wired to the pendulum, labeled "Apollo Pulsed Integrating Pendulum, 16, Mod. D, Part No. 108000-2, Serial No. 2AP297." With wires taut, the complete assembly measures approximately 9″ x 2.5″ x 2.5″. In fine condition. Three of these are used in the Apollo Inertial Measurement Unit (IMU) and provided the acceleration information to the Apollo computer for navigation and guidance. The Apollo Pulsed Integrating Pendulous Accelerometer (PIPA) was based on the Polaris missile accelerometer used in that missile’s guidance system. MIT Instrumentation (Draper) Lab designed the Polaris PIPA and chose to use that design for the Apollo PIPA because of the tested and established accuracy and reliability of the Polaris design.
