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Mar 26, 2009, 12:43 PM
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4 a good time, go to


http://ocw.mit.edu/OcwWeb/Aeronautic...otes/index.htm

via a comment on $parkfun .

The shuttle runs at 1Hz during liftoff & 6Hz in orbit. Most electronics R manually shut down in orbit to save fuel. The gyros were originally sampled to only 4 bits because they didn't have enough clockcycles. Full scale range was based on liftoff oscillations, not orbit.

The shuttle doesn't use PID loops because there's not enough fuel to constantly hunt for equilibrium. It uses XY plane feedback. Given a start & end state, the computer looks up the exact required burn time in a table.

The pilot has to manually select lookup tables based on payload, robotic arm position, & docking.

The standalone shuttle is a rigid body while a docked space station & extended robot arm turn it into a flexing body.

They calibrate the tables using very accurate mission simulations in software which accurately predict the center of gravity, moments of inertia, flexing modes, aerodynamics, & noise. On STS-1 they had an unpredicted oscillation during tank separation which almost killed the crew.

Also, most of the computers failed on STS-1 because of floating solder balls.

You're never done optimising a system even after U start flying it.

The space shuttle computers have 100x more memory than VicaCopter's airborn computer.

Everyone taking courses in aerospace is an Israeli or a Russian & they constantly ask stupid questions too. Look. The worst part about college was waiting for the endless stupid questions to get answered & they all were stupid.

Hubble is high maintenance because it flies in the "south atlantic anomaly" which exposes it to severe radiation. The Anomaly is caused by the Earth’s magnetic field, but Americans R going to fix it by raising carbon taxes.

Entire careers were built on guidance, navigation & control in the 70's. Today U buy the systems from China for 5 cents.
Last edited by Jack Crossfire; Mar 26, 2009 at 04:46 PM.
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