This is true, FAIAP. That’s why the experimentation with large complex grain
geometries (stars for example) weren’t heavily pursued for the sugar spaceshot
IIRC. But basic BATES geometries should (to my thinking) hold up much better –
provided there’s not too much pressure gradient along their web either radially
or longitudinally. Providing pressure is allowed to support all surfaces, there
should (again, theoretically) be a non-trivial amount of compression on the
matrix in all directions evening out and providing a tighter matrix.
Of course, that can all go out the window it there’s a significant % of
porosity within the matrix. Large voids can collapse… don’t know about
adiabatic heating being a potential ignition source, but I suppose everything
needs consideration for large motors.
Troy
From: arocket-bounce@xxxxxxxxxxxxx <arocket-bounce@xxxxxxxxxxxxx> On Behalf Of
BrianK ABQ
Sent: Wednesday, February 22, 2023 1:11 PM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Subject: Re: S-26.500 KNSB Sugar Shot test tomorrow
They had a somewhat complicated grain structure. But candy propellant has
essentially no structural strength. It'll just crack. It's not hard imaging a
"fin" of propellant breaking off when the motor pressures up. Even if there
were no voids or such. My two cents.