Gregory's ServerHere's a closeup of the gears and differentials that perform the computations. 4/12
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 The CADC receives pressures from the aircraft's pitot tube. One problem is that the airflow over the aircraft distorts the static pressure reading. The fix is to apply a Pressure Error Correction factor. This factor is determined by the Compensator, an external unit. 6/12 The Compensator uses a 3-D cam to generate the correction factor, sent to the CADC as a synchro signal. The CADC uses a servo loop to generate a rotation corresponding to this factor, then multiplies it with a differential. 7/12 An amplifier board uses transistors and magnetic amplifiers to drive the motor that turns the shaft. They didn't use a printed circuit board, but components soldered to metal pegs. Here's the schematic I reverse-engineered. 8/12 The CADC is a boring cylinder from the outside. You wouldn't expect that amazing mechanical complexity would be found inside. 9/12 For more information, see my blog post: https://www.righto.com/2024/02/reverse-engineering-analog-bendix-air.html 10/12 You can see the Bendix CADC in action in this thread: Credits: thanks to Joe for providing the CADC. I worked on it with https://twitter.com/curious_marc and https://twitter.com/TubeTimeUS; Marc made a video of the CADC:  @foma_econlodge The CADC computes airspeed, Mach number, temperature, air density, and other "air data".  @kenshirriff : Wow! You are a legend! π²π²π² Thank you, kind Sir, for this knowledge! |
The outputs from the CADC are transmitted electrically to other parts of the aircraft.
Cylindrical devices called synchros convert shaft rotations to 3-wire electrical signals. This diagram shows the synchros and other components inside the CADC. 5/12