That's why when I joined Deep Space Industries, I steered them away from
Peroxide/alcohol to Peroxide/Propane, which can self-pressurize the fuel,
and supply vapor to the RCS via a relief valve and heat exchanger.
There was No Damn Way I was going to work with peroxide-alcohol. Propane
has higher Isp, anyway.
On Sat, Jul 2, 2022 at 5:21 PM John Schilling <john.schilling@xxxxxxxxxxxxxx>
wrote:
LOX/LH2 is rated at 15% TNT equivalence above 200,000 lbm, and "only" 60%
for low quantities IIRC. A "slurpee", as you put it, can only react at the
interface surface between the two components, and while it will give you
the full energy release *eventually*, it doesn't all contribute to the
initial shock. For realistic levels of mixing in plausible
launcher-accident scenarios, experimental testing gives you the 60->15% EEW
curve.
LOX and LCH4 are fully miscible, with an overlapping liquid range. And
when they mix, they are known to be an extremely brisant detonable high
explosive, once considered for hard-rock mining before everybody who played
with the idea realized that it was way too sensitive to be handled even
remotely. That's not something we've seen in any other common propellant
combination - either the components don't have a common liquid range and
can't mix before igniting, or they're hypergols and they can't mix before
igniting, or they're chemically immiscible in the same way as oil and
water. If someone were daft enough to use hydrogen peroxide and alcohol,
that would have the same problem. And now I'm wondering if anybody has
studied the miscibility of things like chlorine pentafluoride with common
fuels...
John Schilling
On 7/2/2022 1:25 PM, roxanna Mason wrote:
No one's mentioned a slurpee of liquid hydrogen and fine powder solid
oxygen. Is a pad failure of a Delta 4 any worse than a Falcon heavy?
Brisance is what shatters things like concrete non necessarily total
calories/joules released.
Ken
On Sat, Jul 2, 2022 at 8:46 AM Henry Vanderbilt <
hvanderbilt@xxxxxxxxxxxxxx> wrote:
On 7/1/2022 9:52 PM, Henry Spencer wrote:
On Fri, 1 Jul 2022, willsrw@xxxxxxxxx wrote:I seem to recall that the canonical worst-case for a LOX/CH4 (quite
I’m surprised the conversion is assumed to be one to one. A one to
one conversion (propellant to TNT equ) means 100% mixing to a perfect
mixture ratio throughout the entire volume of propellant.
No, not nearly -- methane's heat of combustion (complete combustion,
oxygen included in mass, but assuming water vapor produced remains
vapor) is 10.0 MJ/kg, while nominal TNT energy output is about 4.6
MJ/kg. Even considering that a typical propellant mix doesn't contain
enough oxygen for complete combustion, LOX/CH4 is quite a bit more
powerful than an equivalent mass of TNT. Perfect mixing would yield
close to 200%.
Difficult to do.
But much less difficult than for LOX/LH2 or LOX/kerosene, where the
large temperature difference gets in the way. That's why people are
wary of LOX/methane, in the absence of large-scale tests -- good
mixing is much more plausible when the two liquids are at about the
same temperature and are fully miscible.
mutually soluble) launcher explosion is launch from a pad with a large
flame pit or trench, propulsion failure shortly after liftoff causing
booster to fall back onto the pad, either directly into the flame pit or
the propellant then drains into the flame pit, then considerable mixing
takes place in the big tub of propellant before any ignition. Big
Badda-BOOM! Roughly 50% of the total propellant-load potential
explosive yield seems a reasonable first approximation for such an event.
The scenario came up in discussion here, in fact (could we have thought
of it first? Seems unlikely, but you never know.) In any case, planned
launch pads for LOX/CH4 boosters do now tend to lack large flame
trenches or pits.
Mind, a common-bulkhead failure between LOX and CH4 tanks could produce
something similar in flight. Nobody seems to be pushing for
common-bulkhead LOX/CH4 storage either, oddly enough.
Henry
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