Troy:
I concur.
Switching from aluminum tube (1600 psia burst; 640 psia operating pressure)
to carbon fiber (order 2000 psia burst; thinking about 1200 psia operating
pressure) produces significantly more performance benefit than higher
propellant density.
My underlying question here is whether vibration and vacuum can do away w/
conventional mixing altogether *and* whether that is lower cost and no more
dangerous.
Bill
On Wed, Jan 29, 2020 at 3:57 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx>
wrote:
Bill, the economics of achieving a closer measured to theoretical density
is by far a secondary virtue. The primary is the added reliability from
increased propellant integrity especially if there’s structural scope to
operate at higher chamber pressures, which itself is more of an economic
decision.
Troy
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
*On Behalf Of *William Claybaugh
*Sent:* Thursday, 30 January 2020 4:51 AM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: Vibratory compaction
Shane:
Is this done after or during mixing?
If the latter, I—and I suspect others—would be very interested in your
process: for example, how long do you apply vacuum / vibration before
casting the grain(s)? Have you documented the difference in final
propellant density?
I found that 10 minutes under vacuum after mixing resulted in density
going from 0.055 to 0.058 lbsm. / cu. in., for a specific propellant
formulation, for example. Do you have a guess as to what additional
density might be achieved from vibration? Note that theoretical is 0.065
for this propellant.
I’m trying to make an economic calculation here: for my next generation
(composite) 6” motors, getting to 0.060 lbsm. / cu. in. Increases
propellant fraction from 70% to 72%; given my estimate of the cost of a
vibratory table, I’m looking to understand if that investment produces
greater performance gain than alternative weight saving investments.
Bill
On Wed, Jan 29, 2020 at 10:34 AM <spcdestiny01@xxxxxxxxx> wrote:
At my school we use the vacuum while it’s on the vibration table to remove
all air bubbles and increase the density.
Hope that helps,
Shane Cullen
Sent from my iPhone
On Jan 29, 2020, at 10:27 AM, William Claybaugh <wclaybaugh2@xxxxxxxxx>wrote:
propellant, with or without vacuum?
Anyone have experience w/ vibratory compaction if solid rocket
Initial search did not turn up anything specific....
Bill