On 3/3/2018 3:05 PM, Henry Vanderbilt wrote:
On 3/3/2018 3:42 PM, Henry Vanderbilt wrote:Nitrous should work, but I'm looking at an old DTIC report <http://www.dtic.mil/dtic/tr/fulltext/u2/268731.pdf> that got decent results from Freon. Looks like their application was for the old Subroc system, whic as the name implies was meant to be used aboard submarines and so wanted the safest possible liquids.
On 3/3/2018 3:20 PM, John Schilling wrote:
If I were doing it today - and the cost and complexity of gimballed solids is such that I'd seriously consider it - I'd use an aqueous HAN solution as the fluid. Only about half the free oxygen of NTO, but at least an order of magnitude less hassle on the pad. And yes, run the fluid at constant rate calibrated to run out right after the motor burns out, with steering done by a proportional four-way diverter. There's no excuse for that causing leakage on the pad; the diverter valve almost by definition can't be leak-tight but it does mean you only need one leak-tight valve upstream of the diverter.
Well, OK, one series-redundant valve train. And I'll even consider a pyrovalve for this application, since we're going solid anyway.
And, circling right back to where we started (the question of what sort of high-performance solids might be doable by a serious university team) simplified liquid-injection TVC actually sounds like something that might be a worthwhile and achievable enhancement to the current non-professional state of the art.
I'd be tempted to gain experience and work out the bugs on a medium-performance first pass, mind - an off-the-shelf solid, plus a relatively benign albeit low-performance TVC fluid, to develop an initial flight demonstrator. Save aqueous HAN (or maybe peroxide?) TV-fluid and shooting for 100 km for a subsequent iteration.
Duh! For a KISS liquid TVC demo, what do you think of nitrous for the TVC fluid?
Henry
