Citing for explosives for rocket operations is a bit more complicated
than just for storage. There are several different exclusion radii for
different things. Like distance to affiliated personal, non-affiliated
personal, non-affiliated structures, etc. The radius of the circles
are larger for the same quantity of explosives for 1.1 than 1.3. This
is only for handling operations however, so it is mainly applicable to
solids. Launch clear areas are much different. The radius for these to
any personal is 2 miles, and this is for both 1.1 and 1.3 rockets, I
think some heavy lift vehicles have larger circles. These distances
will be specified in launch licenses for the different ranges, as well
as in the launch provider license for the rocket. It also can vary
depending on who is sponsoring the launch (NASA, FAA, DoD). As they
each have different requirements.
TNT is 1.1 it is possible that LOX/Methane might be treated as a
higher class of explosive, I haven't actually looked. I am fairly
certain it is treated the same, I have a tough time imagining it would
be worse than LH2/LOX. The class of explosive is primarily related to
it's sensitivity and its propensity for sympathetic detonation. Though
energy content and detonation velocity might have some part. They
don't really look at the energy content as much since 100,000 lbs of
TNT would have relatively similar effects to 100,000 lbs of HMX,
despite one being a more powerful explosive. Distances are not
determined in a sensitive enough way that it would make a difference,
All you care about is "A big ass explosion happened" which is
determined by how much of the fuel is likely to detonate
simultaneously.
I don't think you would make an assumption of 100% mixing, unless you
are actually premixing it. I am fairly certain you would assume
partial mixing. Since it would be partial mixing (even to a high
degree) you wouldn't get simultaneous ignition of the entire quantity
of fuel. Which is what would probably make it a 1.3.
It has been several years since I was last involved in this kind of
stuff, so your mileage may vary.
On Tue, May 24, 2016 at 1:21 AM, George Herbert
<george.herbert@xxxxxxxxx> wrote:
Yes. The worst worst case would be complete, effective mixing of the
propellants to a single mass of liquid, slush, or gel which is
catastrophically detonatable in bulk. Ignition could rapidly cause
detonation in bulk.
That would be HE 1.3 equivalent. Plus some as it's more energetic than TNT
per kilo.
George William Herbert
Sent from my iPhone
On May 24, 2016, at 2:09 AM, "John Dom" <johndom@xxxxxxxxx> wrote:
The ATF website relates to high explosives, rather than rocket fuels, right?
jd
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of George Herbert
Sent: dinsdag 24 mei 2016 7:49
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: LOX-Methane Kabooms
https://www.atf.gov/explosives/555218-table-distances-storage-explosive-mate
rials-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:<John.Schilling@xxxxxxxxxxxxxx> 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
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