I looked closer at my 250 lbf aluminum chamber in preparation for the
next series of tests and there may be some coking deposits in the
cooling passages. When I shine a light at one end and look through the
other end, a few of the holes seem slightly darker than others so I can
only assume that is due to coking from the fuel (kerosene). Does anyone
have suggestions on how to clean up the holes? I was thinking of
chucking up a wire brush in a drill and running it down in the holes but
a solvent would be preferable. Or I could just use the original sized
drill bit and run it through by hand to try and scrape some of it off.
I did come across a patent where you can heat up the engine and run
ozone through it to remove the deposits but that doesn't sound like an
"at home" project. At Space Access, I recall someone mentioning that
Naval Jelly (phosphoric acid?) will work.
The total run time of this engine to date is around 80 seconds.
-Bob
