[AR] Re: arocket Digest V9 #9
- From: Keith Henson <hkeithhenson@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Sat, 16 Jan 2021 10:52:17 -0800
On Sat, Jan 9, 2021 at 10:08 PM Dr Edward Jones <RocketPioneer@xxxxxxxxx> wrote:
Has anyone first-hand experience with vacuum degassing hot batches of
KN-Sorbitol precasting?
No, but I have degassed a lot of epoxy and the silicone rubber used
for epoxy molds.
Steel is degassed by pouring it through a vacuum. Which makes sense
because the pressure at the bottom of a ten foot deep crucible would
be well over an atmosphere. If the depth of the container for the
rocket fuel is shallow, static pressure at the bottom should not be
significant. If you can set it up, pump down the rocket body and hot
pour then break the vacuum before it cools off. This will keep from
entraining air bubbles. My experience might be applicable if the
viscosity of your rocket fuel is about the same viscosity as the sand
filled epoxy we used (somewhat similar to molasses or honey). We
didn't use a very high vacuum, as I recall, it wasn't better than
1/100th or 1/1000th of an atmosphere.
I've heard that's an advantageous process, but
have never found the need. Will degassing created a denser grain
You can make some samples up and measure the density. Unless the
current ones are really full of air, I don't think it will make a lot
of difference.
with
higher Isp? How much can effective degassing of KN-Sorbitol
formulations improve performance?
As to that, I can't say. I suspect it isn't going to affect the ISP
much, but it might burn smoother.
Keith
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