Scarce Apollo Block I simulator-used Command Module Flight Director Attitude Indicator (FDAI). Unit is contained in its original housing and measures approximately 8 x 8 x 10. A Honeywell parts label is affixed to the bottom of the housing and reads, in part: “Indicator, Attitude Flight…Mfr. Ser. No. 10028EAN1024…Mfr. Date 4 Dec 1965.” There is a light red inspector’s stamp next to the label, and “D4C-1024,” scratched into the casing. In fine condition. Manufactured by Honeywell, this square version was the first type of this piece of equipment. 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 white 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 whom were pilots, lobbied for an all-in-one device similar to the artificial horizon indicator in airplanes.
Terms and abbreviations used in our descriptions.