[AR] Re: Spiral Burn Solid Propellants
- From: David Weinshenker <daze39@xxxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Mon, 4 Jul 2016 12:50:15 -0700
On 07/04/2016 12:47 PM, Ed LeBouthillier wrote:
David Summers said:
We've done that at UTS. It works pretty well, you can get some crazy
long burn times!
Yeah, I’ve been able to easily simulate burn times of 70-ish seconds for
spirals versus 5-ish seconds for
an equivalent weight/shape Bates grain. The thrust scales appropriately
too (5 lbf vs 71 lbf respectively).
This was an extreme example, but more modest trades are also possible.
It seems that you can
tailor the thrust profile to be exactly what you want (within the total
impulse limits).
But, as I said in the last post, I’m just getting to the analysis of the
inert mass fractions so that I
can compare them against other approaches. I’m pretty impressed with the
initial concept, though.
Seems like a spiral is basically going to be a compact way to package
something that's functionally similar to a long slender end-burner...
although I could see possible reduction in flow drag if the aft part
of the internal spiral-forming insulation structure were to ablate,
so the gas from the burning of the forward part of the propellant
didn't have to traverse the long spiral path... I could see also
reduced requirements of outer insulation in such a configuration
(compared to the insulation of the aft part of a thin end-burner
which is traversed at full speed by all the gas from the burning
of the propellant forward of it).
-dave w
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