[ERPS] Flight Unsuccessful

[John Carmack]

Everything was going well, operating at the Oklahoma Spaceport was working out great, the water test and engine warmups were fine, the liftoff was fine, ...

Then the rocket started pitching over, did a complete flip, and crashed into the ground from a couple hundred feet up.

Telemetry had ceased from the rocket after the first second at full throttle, and apparently an attitude engine had stuck on. The telemetry did show a precipitous drop in the battery voltage from 12.1v to 8v in the last half second before failing. At first, I was worried that something might have shorted, and drained the battery rapidly. When we got the electronics box out of the rocket, one of the battery connectors was not on. It might have happened during the crash, as there was quite a bit of general destruction, but the battery still had 12v on it, so we have strong evidence that the connector wiggled off during flight.

I have always been a little worried about the fast-on connectors on the batteries we use, and this clinches it. If I can't find batteries in the size we need with ring terminals, we are going to solder the fast-ons directly to the batteries. We are also going to make a redundant battery power supply.

Starting on a new frame tomorrow, and hoping that the inertial unit is undamaged. Sigh. A few other good lessons learned, more in the update this weekend.

John Carmack

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