Sunday, February 24, 2008

Redlines and Blown Gaskets

I performed two tests today and while I basically failed my objectives, there was some good news. I moved the oxidizer valve closer to the injector hoping to get better throttle response. I also modified the ignition sequencing. The net result was less than desirable - I had a hard start on the second test of the day.

As you can see in the picture, there is fire coming out of the flange that holds the injector plate onto the chamber - the gasket failed when the combustion chamber pressure hit ~1000 psi momentarily. The good news is that there is no other damage to the motor and gaskets are easy to make.

The other bit of good news is that my redline software performed exactly as it was intended to do. I created a module in the DAQ software that triggers when any of the 4 analog channels I'm monitoring (thrust, chamber pressure, injector pressure, tank pressure) exceed predetermined values. When the redline module triggers, it sends a logic signal to the engine controller module and the engine shuts down. In both tests today, the redline was triggered and the oxidizer valve closed. The second test, pictured above, had a duration of about 0.5 s before the valve closed.

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