More on dimethyl sulfoxide:
I punched it into RPA. The sulfur burns into a variety of chemicals,
as expected. Regarding the smells of the exhaust: SO2, sulfur dioxide
exit mass fraction 0.3095672, is "a toxic gas with a pungent,
irritating smell", but is used in food preservation. Carbonyl sulfide,
COS exit mass fraction 0.0000372, is "a colorless flammable gas with
an unpleasant odor", again present at trace quantities in food.
Everyone knows the smell of H2S, hydrogen sulfide exit mass fraction
0.0001823.
Running it with LOX the ideal O:F is around 1.4, giving a bulk density
of 1.124. At 1000psi with expanded nozzle in and at 1 atm, Isp is 268.
Ethanol in the same engine does 289 at 1.8 O:F, but the bulk density
is 1.015. DMSO has 92.7% of the Isp but ethanol has 90.3% of the bulk
density, so there is a marginal total impulse gain from switching a
given total volume of propellant from ethanol to DMSO. But that
implies the existence of a rocket of fixed total volume but a variable
tank volume ratio, which isn't particularly realistic.
So as a normal bipropellant it is fairly uninteresting, especially
considering the bad things likely to happen if you run it through
copper cooling channels.
Its likely peroxide miscibility and low autoignition temperature may
still make it better in a mixed monopropellant peroxide engine than
ethanol. With 50% peroxide at O:F of 4.5 (using 50% peroxide as the
'O' mass) Isp is 185, compared to 158 for 100% peroxide monoprop in
the same 'engine'.
$46 per gallon on Amazon: http://amzn.to/29jVJQI . Or if you want to
get on two government lists at the same time, you can get deuterated
DMSO from Sigma Aldrich, $100 for 5 grams.
RPA outputs are here:
https://docs.google.com/spreadsheets/d/1Dqs4zEio8SYyT9tJ_PXvQ2mFfPq4OnmINrUKTbyAJEI/edit?usp=sharing
Now I should probably finish what I sat down at the computer to do,
and then go tourist Copenhagen. I visited Peter Madsen and his new
rocket project yesterday, and plan to visit Copenhagen Suborbitals on
Saturday.
Ben
On Tue, Jul 5, 2016 at 6:19 AM, Ben Brockert <wikkit@xxxxxxxxx> wrote:
DMSO is basically ethanol with a sulphur added that will make the
exhaust grosser. C2H6OS vs. C2H6O for ethanol.
In pure form it is lower toxicity than ethanol, but it has the strange
characteristic of giving some people the taste of garlic when it's
spilled on skin. It has the ability to be absorbed through skin and
carry other molecules, so wearing gloves while handling mixtures would
be a good idea.
Clark doesn't mention it in "Ignition!".
There is a pending patent listing it with a dopant for hypergolic use
with HTP: https://www.google.com/patents/US20120273099
The reason I was looking at it is because it has an unusually low
autoginition temperature of 215C, vs. 365C for ethanol. The high
autoignition temperature of alcohols is one of the problems that make
mixed peroxide/fuel/water compositions difficult to make work
reliably; at high enough water concentrations to make the mixture not
detonable the catalytic temperature drops too low to ignite the fuel.
DMSO is miscible with water, so it's likely miscible with
peroxide/water mixes.
I'll likely never get to the point of card gapping it, but if someone
is into chemistry experiments it might possibly be a non-detonable
mixed monopropellant with a higher performance than pure HTP.
Unusually high density for a fuel too, at 1.1 g/cm^3.
Let me know if you're launching it and I'll stand upwind.
Ben