Very rare and highly important Apollo Lunar Module Flight Director Attitude Indicator (FDAI). Unit measures approximately 5.75 x 5.75 x 11, with the top of the metal cased unit bearing a Lear Siegler manufacturer’s label, identifying the part as an “Indicator Attitude,” part number P 144200-07, serial number “13,” and model number “4068C.” Unit also has an electrical connector protruding from the back. Two of these would have been installed on board each lunar module. Unit is not flown.
The red, black, and white ‘8 ball’ was used to define the relative position of the spacecraft in three-dimensional space. The pitch attitude is represented by the large semi-circles (horizontal relative to the numbers on the ball). The yaw attitude is represented by the small circles (vertical relative to the numbers on the ball). The semicircle immediately under the ‘wing’ is the current pitch angle. The two red circles centered at yaw 0 and 180 degree poles indicate where the inertial guidance gimbals are in danger of locking (gimbals from two axes aligning with each other) causing loss of attitude reference. Indicator has its original glass interface with three yellow bars over the top, which showed the error in each axis, from the desired value, by the displacement of the right and bottom of the ‘8 Ball,’ and also has its three rate needles on the sides of the display. Originally designed to be three different panel instruments, the astronauts, many of which were pilots, lobbied for an all-in-one device similar to the artificial horizon indicator in airplanes. Two of these units would be installed on each Lunar Module. While FDAI’s from the Command Module have previously been offered, our research has not found an example of another Lunar Module FDAI coming up for sale. An outstanding, intact example of one of the most important instruments necessary for space travel. RR Auction COA.