rocket motor static test

[doverdx]

Why am I not surprised that you burned your wood test fixture? Shouldn't you account for hard starts? That is what look like happened.

[swankaerospace]

Thanks for your comment. The test fixture is steel and concrete. the shed doors are wood and they got a bit scorched. the failure was due to a chamber wall burn through at the nozzle throat due to inadequate cooling due to poor design. the start was not "hard". Chamber pressure never rose above 75 psi.

[doverdx]

oh. sorry about that.

what was your chamber made of? what was your injector pattern like?

in addition to regen, have you tried altering your injector pattern to create a gas film on the walls of your chamber? this may save you from burn-throughs...

[swankaerospace]

Chamber was made of copper. Turns out was too weak especially at elevated temperatures. The kersosene injector was a full cone BETE spray nozzle located in the center of a ring of n2o 'showerhead' injector holes. I was counting on an extremely rich mixture to keep chamber temps down. On next version I am planning for film cooling, a higher cooling jacket flow velocity and construction of 304 SS. I am on hold now for lack of funds.

[doverdx]

sounds like some good modifications.

if you are looking into the 3xx series SS take a look at 309 SS. it is a tad more expensive but has better high temperature performance. good luck!