It's been twelve years since I bought my last batch of Exxsol D40, so I
can't remember the specific vendor. At the time, I looked around the
net for industrial chemicals and solvents vendors, then checked prices
till I found the best deal and ordered a few 55 gallon drums. I have no
reason to doubt Doug's recollection that it also could be had in 1 and 5
gallon containers, but at the time we were feeding intensive X-Racer ops
so drums it was. The price was fairly strongly linked to current oil
market prices, thus likely on a low swing right now. I dimly recall
price may have been on the very rough order of 2-3X the current $/gallon
price of regular gasoline? It's been 12 years.
Hmm. And, searching for US Exxsol vendors, I came across Brenntag's US
branch https://www.brenntag.com/en-us/products/aliphatic-hydrocarbons/
which rings loud, loud bells. I'm moderately sure that's where I
ordered it from, back in the day.
Henry
On 10/14/2020 12:44 PM, Tyler Adkison wrote:
Interesting. I've done some tests with kerosene in an ablative chamber where we used K1 lamp grade, which was perfectly satisfactory for our application and easy to source from a local hardware store.
I've never heard of Exxsol D40 before. Do you order it directly from the manufacturer? What sort of price does it go for and what are the minimum order quantities?
On Wed, Oct 14, 2020 at 10:29 AM Doug Jones <rocketplumber@xxxxxxxxx <mailto:rocketplumber@xxxxxxxxx>> wrote:
I also agree that IPA is an excellent fuel for all the reasons
listed above. We used it in four engine designs, and since I used
it to clean the kerosene combustion sludge from the Rotary Rocket
high pressure LOX-cooled kerosene engines I suggested it in 2000
because I was damn tired of cleaning up sludge. (The LOX cooling
condensed partial pyrolysis products out of the 2.6:1 O:F main
combustion remarkably well, resulting in several millimeters of
undoubtedly carcinogenic black slimy crud. In later
kerosene-cooled engines the crud didn't occur, but IPA is simply
MUCH easier to work with.)
If you must use kerosene, use Exxsol.
On Wed, Oct 14, 2020 at 5:49 AM Ben Brockert <wikkit@xxxxxxxxx
<mailto:wikkit@xxxxxxxxx>> wrote:
Thirding the arguments to use Shellsol/Exssol D40 or isopropyl
alcohol. I’ve used both and had good results. I’ve also used
liquid methane, denatured ethanol, and RP-1 and don’t think
they are as suitable.
If you add a small percentage (~1%) of PDMS to isopropyl you
get a similar/better thermal effect to the char layer of
kerosenes; about 50% reduction in heat flux across the wall.
Sold as 50cst silicone oil. It’s not soluble in ethanol though.
In general alcohol rockets are easier (fuel spills are
forgiving, it purges easier, there’s more volume of fuel for
coolant, you need it on hand for LOX cleaning anyway) but
kerosenes are more relevant to future industry work.
Both work fine in spark torch igniters running off tank
pressure, which is the most effective way to make a reusable
rocket engine. And even if the rocket is expendable it’s best
practice to build the engine to be reusable because you want
to test it easily. Pyro igniters are a pain in the ass and
TEA-TEB is a big hurdle for a student or amateur group.
Both competitors that won prizes in the NASA-funded Lunar
Lander Challenge a decade ago were running spark torch ignited
lox/alcohol rockets.
Ben
On Wednesday, October 14, 2020, Robert Watzlavick
<rocket@xxxxxxxxxxxxxx <mailto:rocket@xxxxxxxxxxxxxx>> wrote:
One thing I will mention is that for a regen engine using
kerosene-type fuels (kerosene, Jet A, RP-1), you get a
benefit from the carbon deposits in the combustion
chamber. There are some plots in NASA SP-125 as it acts
as an insulator and reduces the heat transfer to the
walls. Obviously people have made LOX/alcohol work but
just thought I'd point it out as it could potentially help
your cooling problem converge, especially at smaller
thrust levels. It does make it harder to clean up
afterwards as you have to use an abrasive (scotchbrite) to
clean it off. Other than the potential for coking in the
cooling passages on long runs, Jet A, RP-1, and kerosene
should be equivalent. I've never seen any coking in the
cooling passages for runs < 30 seconds. However, if I was
doing a new engine, I would try to make LOX/alcohol work
before I went with kerosene, just from the cleanup
factor. I will say one thing though, you know when you've
cleaned all the kerosene out as it has a strong smell so
maybe it's less likely that you'll leave some fuel in a
place where it shouldn't be.
-Bob
On 10/14/20 3:03 AM, roxanna Mason wrote:
Everything combustible ignites easily in a pure oxygen
atmosphere and Jet A evaporates surprisingly fast
compared to standard kerosene or RP-1.
Ethanol also has a volumetric O/F of unity and easily
adjusted by biasing the mass O/F and/or water
concentration, also the least toxic of the common alcohols,
there are denaturing formulas that are lower
toxicity than others just shop around. You can get a
federal permit to make your own ethanol too w/o the
$28/gallon excise tax. Also has a somewhat pleasant
sweetish odor especially compared to the doctor's office
smell of rubbing isopropyl alcohol, but that is
subjective. And there's tons of data on LOx/Ethanol
systems being by far the most used alcohol in history as
rocket fuel including the V-2 and Redstone ballistic
rockets, the X-1 LR-11 manned rocket planes etc. See pic
of a single chamber LR-11 captive test of one metric ton
thrust, LOx/75% ethanol.
Again it all depends on your requirements and cooling
method. Performance wise you can't beat hydrocarbon fuels
compared to the alcohols.
K
On Tue, Oct 13, 2020 at 11:41 PM Wyatt Rehder
<wyatt.rehder@xxxxxxxxx <mailto:wyatt.rehder@xxxxxxxxx>>
wrote:
I've long maintained that Isopropyl Alcohol is the
ideal propellant for the amateur liquid rocketeer.
- Has a close to 1:1 volumetric O:F ratio with LOX
which simplifies your feed system some (can use
similar tank design for both)
- Is easy to obtain at 99% without additives for a
low cost (~$500 for 55 gal last I checked) and no
regulation issues
- Has a high vapor pressure and does not leave a
film. So spills take care of themselves, doesn't
leave residues in your chamber after you purge it
- You can perform your LOX service cleaning with it
- Has a short bio-persistance, as it readily
biodegrades in soil and water. So regular spills at
your test stand, or a splattered rocket isn't going
to contaminate the ground soil unlike how kerosene
can. Granted this isn't a huge issue at amateur scales.
- Wyatt
On Tue, Oct 13, 2020 at 10:01 PM Henry Vanderbilt
<hvanderbilt@xxxxxxxxxxxxxx
<mailto:hvanderbilt@xxxxxxxxxxxxxx>> wrote:
Alcohol is easier to source and to work with,
yes. Generally easier to get to ignite reliably
and combust stably/efficiently than kerosene,
also considerably easier to purge completely from
small engine passages between firings too. If
you do go with alcohol, you might consider
isopropyl rather than ethanol - it also can be
watered down for extra cooling at need, it's
generally cheaper, and there are no concerns over
what they may have "denatured" it with since it's
not drinkable in the first place.
One factor to keep in mind in deciding, by the
way, is how close to the limits of your team's
available time, talent, and resources will your
project push? (Keep in mind the first rule of
projects: EVERYTHING takes longer and costs more
than planned.) One way to improve the odds your
team won't hit a wall short of useful results is
to simplify wherever possible at the start.
If you do prefer to work with kerosene for the
better post-graduation industry applicability,
one possible lower-cost easier-availability
substitute for RP-1 is a refined-kerosene
industrial solvent called Exxsol D40. It does
not have RP-1's density, thus is somewhat lower
performance, but it is non-coking, fully
evaporable with no residue, is reliably
consistent chemically, and you can buy it by the
drum for a few bucks a gallon. And it's more or
less as difficult to get to ignite, combust, and
purge cleanly as any other kerosene, so you will
get plenty of relevant experience.
FWIW XCOR used LOX/isopropyl for the EZ-Rocket
(before my time there) and LOX/Exxsol D40
kerosene for the X-Racer. Never saw a trace of
coking with it in many, many firings of the
copper-chamber regen-cooled X-Racer engine, and I
was the guy who photo-documented the state of the
engine components every time Mike Laughlin
disassembled it to inspect condition and service
the seals.
good luck!
Henry
On 10/13/2020 9:42 PM, Yucca Works wrote:
Hello all, my team is considering RP-1 and
ethanol right now (to be paired with LOX) for
our main propellant and I was wondering if
anyone has any input on which fuel to use given
some constraints and thoughts to follow. For
one, we don't have an infinite budget at our
disposal so Ethanol becomes immediately
appealing because it is easy to source, this is
on top of the fact that Ethanol is not ITAR
protected and can be mixed with water for
"inherent" cooling. What made RP-1 appealing was
the fact that it is used in the industry so
gaining experience with it seems extremely
appealing and, I think, would make our work more
"useful/notable" but sourcing RP-1 is difficult
and it is expensive. A slightly tangential
consideration is using lower grade kerosene
which I have seen other college students do but
I am concerned with using low-grade kerosene in
regen cooling channels and it obviously has poor
performance.