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 Flight Computer

The Flight Computer is a modified version of the Flight Computer Jay Marsh developed for his Saturn-IB, and also used by Tom Campbell in his Saturn-IB. Two "Basic Stamp" microcontrollers are used for the computer.

One Basic Stamp essentially looks at the status of sensors, such as Ejection charge continuity, Liftoff detect, Thrust detect, and Orbiter sep. The other carries out most of the flight program depending on the sequence of the flight and sensor status.

It is powered by 9 volts, in this case a 9.6 volt 50 mah nicad pack. It beeps out a number sequence on the ground to indicate if things are OK, and if not then it beeps an error code (such as no ejection continuity, or liftoff detect before thrust detect). A constant beep of "1" means things are good for launch.

Preflight, it commands a servo continuously to hold a position that keeps the SRB's attached. On a good flight, when burnout is detected, the computer commands the servo to move 1/2 second later to sep the SRB's. The computer waits to detect orbiter sep, when it does, the ejection for the ET is fired 1 second later. A back-up charge is fired 1/2 second after that, normally on a good ejection the back-up charge does not fire since it becomes unplugged as the ejection piston is fired out.

For more info on the Flight Computer's use in the shuttle, go to George's Shuttle Model web page on this CD