Monday, October 22, 2007

Static Test

This past Saturday I participated in a sugar propellant class at the Friends of Amateur Rocketry (FAR) facility. Brent Dougherty did a nice job presenting a general overview of how to safely work with and cast sugar based propellants. Thanks to the FAR guys Kevin, Mark, Ted and the others for letting us use the site. They have done an amazing amount of work on the site, including a massive vertical test stand (I don't remember what it's rated for).

As part of the class I fired an L-class KNO3/Sorbitol demonstration motor. The firing went well and good data was collected. This is a simplified set-up from what I've used in the past and it worked well. I'm planning on making some adjustable steel brackets that mount with bolts rather than the cargo straps. Here is the set-up:

In the picture taken just after the firing you can see the nozzle glowing red hot, once I got the motor torn apart and cleaned, everything appeared to have survived the firing just fine. The gauge measuring thrust began to register data about a tenth of a second or so before chamber pressure began to be recorded. I suspect that the pressure port was briefly clogged by the igniter initially. After tearing the motor apart I found a glob of melted plastic that used to be the soda straw that held the BP.

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