John:
I think I know the report you are referencing.
I agree that nitrous is far more dangerous than commonly understood, but
not for less than about 6 inch (15 cm) diameter rockets, or LITVC tanks.
If one wants low cost, then multiple development efforts are a mistake
(this was SpaceX s error on Merlin, albeit forced by funding constraints);
proving a system w/ Freon—which is largely banned from release into the
environment—and then going to N2O and then to HAN is likely a mistake
compared to starting w/ the solution w/ which you want to arrive.
Bill
On Sat, Mar 3, 2018 at 4:58 PM John Schilling <john.schilling@xxxxxxxxxxxxxx>
wrote:
On 3/3/2018 3:05 PM, Henry Vanderbilt wrote:
On 3/3/2018 3:42 PM, Henry Vanderbilt wrote:
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
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.
So, Mark I amateur system uses Freon, and if/when you need the extra
performance you start testing a Mark II using N2O. Carefully, because it
is an energetic oxidizer even if nominally benign at STP. If you get that
working safely and reliably, you can think about things like HAN.
John Schilling
john.schilling@xxxxxxxxxxxxxx
(661) 718-0955
