I agree that we need to continually look outside the box provided lots of
homework is done beforehand and not too many resources are allocated to that
research.
Compounds or mixtures containing lots of energy are generally pretty
universally unstable whether the energy is in chemical bonds or a
fuel+oxidiser combination just waiting to get intimate with other. This
example had both (particularly in the case of acetylene) so it sure was
going to be a challenge.
Troy.
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Henry Vanderbilt
Sent: Wednesday, 2 December 2015 9:13 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: ALASA cancelled because...
"High performance". None of those, if I'm not mistaken, would provide Isp
competitive with the better biprops, which is the monoprop holy grail people
keep seeking and never finding.
Put another way, just because we need it doesn't mean it's possible.
On 12/1/2015 2:48 PM, George Herbert wrote:
While I generally agree with Henry on monoprops, there are materials likeOTTO fuel, TATB, Fox-7, and Class 1.3 propellants where accidental mass
wrote:
We need stabler monoprops.
George William Herbert
Sent from my iPhone
On Dec 1, 2015, at 1:29 PM, Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx>
have high performance is vanishingly unlikely to be reliably stable under
I'm tempted to propose a rule: Any liquid monoprop energetic enough to
moving the test apparatus.
On 12/1/2015 11:21 AM, Ken Doyle wrote:
That was me on Facebook mentioning that some success with
Nitrous/Fuel mix was had in the gaseous phase.
I worked at Firestar in Mojave for 3 years, leaving in very early 2012.
I'm pretty sure my NDA obligations have expired, and that Firestar
is defunct now.
The fundamental problem with use of a pre-mixed oxidizer/fuel in a
rocket motor is of course the issue of flashback, or a detonation
wave traveling upstream from the burning rocket motor to the tank
holding the mix. We did have success in developing Flashback
Arrestors for the gaseous phase. Those detonations usually didn't
explode the SS tubing on the way to the Arrestor, and diverting the
detonation wave and bursting relief parts kept away the big kabooms.
I setup and ran the tests of the arrestors, and the rocket motor tests.
For actual practical use in a flight motor, the higher density and
smaller plumbing sizes that come with liquid-phase operation were
going to be necessary. The ever-optomistic CEO/Chief
Scientist/Pitchman believed that the liquid phase of the mixes would
be more stable and easier to arrest flashback than the gaseous
phase. That hope proved to not be the case at all.
Although they may have made some progress after I left the company;
while I was there, we were never able to arrest flashback in the
liquid phase.
We did most of the work with Nitrous Oxide mixed with Ethylene or
Acetylene. We did a series of 14 meter Drop Tests of the mixes,
with the Nitrous/Ethylene being much less prone to kerbleweys than
the Nitrous/Acetylene mixes. Although some attempt at subterfuge
was made to make it appear that we had a secret ingredient to help
with stability, no ingredients other than Nitrous Oxide and the Fuel
were actually used.
With the Nitrous/Acetylene stoichiometric ratio mix tested, the
first Drop Test passed, but the second failed violently. The evil
mix had a tendency to explode at unexpected times; that is, in
conditions less severe than it had previously passed through. For
instance, I did a couple of slow heating tests which failed to
explode at up to about 80C. Then, a test where it exploded at only
50C. The difference in the tests was that the 50C explosion
happened on a windy day, with some slight agitation due to the wind
Although the Nitrous/Ethylene mixes could pass some of the basic
handling safety tests, the arresting of flashback detonation waves
in the liquid phase was never solved while I was there.
In spite of highly negative handling safety experience with the
Nitrous/Acetylene mixes, a push persisted to make the stuff work,
due to the higher Isp number possible.
I was also chided about appearing to be afraid of the stuff, that my
cautious handling demeanor went against the company PR that it was
safe to handle...
To sum up my opinion after working with Nitrous / Fuel
monopropellant blends for 3 years; 1. They are too dangerous to be
anywhere near humans or valuable hardware.
2. The single tube/tank plumbing potential benefit is overcome by
the impracticality and weight of feasible flashback arresting notions.
Use of Nitrous and a reasonable fuel such as Ethylene, as a bi-prop,
is worth exploring.
It is conceivable that progress was made after I left Firestar, but
none of my sources ever indicated such.
It is also conceivable that the ALASA / Boeing work with Nitrous /
Acetylene had no influence from the Firestar work, but I doubt that.
Ken Doyle