https://www.atf.gov/explosives/555218-table-distances-storage-explosive-materials-high
300k lbs is 2,275 ft to occupied buildings. And more than a bit liberal. That
will at least blow windows in that far away...
George William Herbert
Sent from my iPhone
On May 23, 2016, at 8:41 PM, Wyatt Rehder <wyatt.rehder@xxxxxxxxx> wrote:
Well explosive quantity safety distance for up to around 1 million
pounds of 1.3 is around 500 feet if I recall correctly, liquids are
typically treated as 1.3. Usually bipropellant liquids rate much lower
on the danger scale than conventional explosives. Main reason being
most liquid anomalies are almost exclusively deflagrations. Mostly
because physical events of a crash prevent much mixing taking place
irregardless of the miscibility of the two liquids. Usually everything
is on fire before it has enough time to mix much.
It would be a rare event that would see significant mixing. Perhaps if
both tanks burst on the pad without igniting you could get some
mixing, but then it doesn't really matter since the standard standoff
distance is 2 miles for any kind of orbital rocket. If the rocket got
any altitude off the pad it is nearly guaranteed to ignite on
crashing.
The explosive safety quantity distance for 225,000 lbs of 1.1
explosives is either 1500 or 2000 ft I cant remember off the top of my
head.
On Mon, May 23, 2016 at 7:16 PM, George Herbert
<george.herbert@xxxxxxxxx> wrote:
I see a need for some testing.
Cough.
George William Herbert
Sent from my iPhone
On May 23, 2016, at 7:24 PM, John Schilling <John.Schilling@xxxxxxxxxxxxxx>
wrote:
Question for the group mind: Has anyone out there come across
a formal methodology and/or experimental data for determining
the TNT equivalence of a LOX-Methane propellant explosion?
Not, I hasten to add, a deliberately premixed one - I think I
classified that potential blend as an "insanely dangerous" mixed
monopropellant in my Space Access talk. But we've now got
multiple launch providers talking about flying LOX-Methane
bipropellant out of the major ranges, and people are starting
to ask for specifics about how big an explosion you might get
in a worst-case accident.
Which presumably would be a low-velocity crash right next to
(or back onto!) the pad after an early engine cutoff, tank
rupture and no immediate ignition so the potential for
extensive mixing followed by detonation. LOX and methane
are fully miscible as liquids at typical storage temperatures,
and not hypergolic, so the usual explanations of why we can't
get 100% mixing and full theoretical energy release don't hold.
With LOX-Kerosene, for example, the "maximum credible event"
is assessed at about 10% of theoretical yield partly on the
grounds that the kerosene will freeze as it mixes.
I would expect that LOX-Methane would be somewhere between 10%
and 100% of theoretical yield in a worst-case crash, but that
covers a fairly broad range - and at 100% theoretical yield,
it probably covers an impractical amount of the Cape in the
blast zone. So, looking for the least troublesome way to
narrow that estimate, and if that comes down to "Yeah, the
experiments are a bitch but the guys at White Sands did that
in 1963...", this might be a place to ask.
John Schilling
john.schilling@xxxxxxxxxxxxxx
(661) 718-0955