Doug:
Interesting idea. I can’t use it on smaller motors as I use BATES grains
that are cast separately but casting of the nine inch motor may be
monolithic; your suggestion could make a lot of sense for that.
I did notice the surface bubbles collapse when we repressurized suggesting
that to be a valid idea as well.
Bill
On Sun, Jul 7, 2019 at 11:52 AM Doug Jones <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
Perhaps you could put the mix in a funnel and extrude it through a small
nozzle into the motor case in a vacuum chamber? With a rubber ball
floating on the surface to block the funnel as it goes empty.
The slender stream of paste should outgas quite well, and rapidly
reconsolidate into a bubble-free mass in the motor. Let it sit in vacuum
for a little while to settle, then slowly ramp up pressure and any
remaining bubbles should collapse completely.
On 2019-07-07 10:39 AM, William Claybaugh wrote:
I ran some static tests recently using a modified version of the
standard RRS composite propellant (10% Al rather than 7%).?? Those
tests included applying vacuum to the fully processed mix ahead of
casting (5 minutes); the mix was still outgassing when we repressurized
This resulted in an about 5.6 % increase in density, of which 0.9% is
attributable to the increased Al loading.
Given that full mixing under vacuum is not viable given the processing
equipment available at the MTA, is there another vacuum schedule that
might provide still higher density?
Does degassing the liquid components before mixing help or does the
subsequent mixing just reintroduce air??? Any recommendations on
degassing time after mixing (recognizing that the catalyst is in the
mix at this point).
Two static tests, one at 390 psia average and the other at 760 psia
average showed a decreased burn rate and a slightly higher ISP as
compared to the original mix, as expected.
Bill
