Explosion @ Scaled Composites rocket stand; 2 dead

[Dr Mordrid]

It's all over Fox News and it was an SS2 engine. It's a real mess.

2 dead, 4 critical

Sounds like a ruptured NOx tank;

http://www.tehachapinews.com/home/ViewPost/26187

Breaking News: Two dead in explosion at Mojave Airport

By: Carin Enovijas, Tehachapi News Editor

Two are confirmed dead following a nitrous oxide "flash explosion" that occurred at Mojave Airport at approximately 2:30 p.m., according to airport security officials. Four others have been flown to Kern Medical Center and treated for chemical exposure and other unspecified injuries. Their condition is unknown and no identities have been released at this time.

The explosion occurred at a sublet testing facility on the airport property.
More information will be posted as it becomes available

[Technoid]

[Evildead666]

I checked about an hour ago and it was 3 dead and 3 injured, of which two were critical.

I hope this won't have any effect on their work...they're doing a good job, and I wouldn't like them to be put on 'Pause' for any length of time...

Lets hope the remaining injured recover fully.

[Evildead666]

http://www.latimes.com/news/local/la-me-explode27jul27,0,3190584.story?coll=la-home-local

[Nowhere]

So...back to NASA with "serious" stuff? :|

[Dr Mordrid]

Not really.

Explosions/fires while tanking gases and flammables aren't that ubusual, unfortunately. Earlier this week a hole was blown in central Dallas, Texas when acetelene tanks were being filled; a valve failed. Almost every week thee are incidents with fuel tankers, LP tanks etc. etc.

A hot day, low humidity, a bad valve or hose plus a little static and boom. Sometimes you don't even need the static.

This can also happen with nitroux oxide if the tanks/hoses were improperly cleaned and a hydrocarbon (grease, oil etc.) left wihin them. It mixes with the liquid nitrous oxide when filled, making a shock-sensitive combination that's an accident looking for a time/place to happen.

Another thing you have to be careful about with nitrous oxide is the presence of warm/hot catalysts, the presence of which can turn nitrous oxide into a monopropellant; no 'fuel' necessary...it just decomposes into N and O.

When we handle it the rocket tank, hoses & fittings get a bath inside & out and are well dried before the nitrous oxide supply tank is allowed anywhere near them.

Even so it's hell and gone easier to deal with than liquid oxygen, concentrated hydrogen peroxide or hypergolics

[Nowhere]

Yep, things happen...but is it far fetched thinking that somebody at "proper position" will say things like "we must regulate those amateurs more/regulate playing with this stuff/leave this to professionals"

PS. And...isn't there perhaps something to it? (asking here more than stating) For example: one of the reasons why US went to the moon and Soviet Union didn't was succes of Saturn V (small number of powerfull engines (and this route is much harder for independent teams for example simply due to...size?)) and failure of N-1 (large number of small engines/undesired interactions between them/inadqute testing (again harder...extensive testing costs much)). And here we have some teams pursuing large clusters of small engines... (the team in which Carmack was/is involved and larger Falcons AFAIK?)

[Dr Mordrid]

Thrust chamber clusters can be highly reliable. Just look at the Souyz launcher; 32 thrust chambers vs. Saturn I's 8 or Saturn V's 5. Soyuz has 1,700 flights under its belt and counting.

A huge advantage to clustering is that it provides redundancy; if 1 or 2 thrust chambers fail non-catastrophically, as is typically the case, the remaining chambers can be throttled up and the mission continues. More than one Saturn V had this happen. Saturn I had 0 failures.

With a low thrust chamber count the remaining ones cannot continue the mission, thus forcing an abort. Aborts are performed by the range safety officer triggering linear shaped charges, splitting the tanks so the booster wouldn't fall into a populated area intact. That is the "boom".

Also; unlike the public perception thrust chamber bursts aren't that energetic, typically chamber fragments can only penetrate ~2mm of aluminum. In fact the adjoining chambers typically continue to function. The explosions that are not ordered by the range safety officer are caused by the blast rupturing the thin fuel tank immediately above it.

To prevent these problems Falcon 9 has blast shielding between the cluster and the tankage and Kevlar between the chambers.. It also has computer controlled valves high in the structure that can cut fuel flow to a failed chamber.

The Futron Design Reliability report looked at booster failures from 1984-2004 and found 6 that were due to engine failures. Of these 6 only one was caused by a ruptured chamber. The other five were plumbing (clogged) or a failure to achieve or maintain full thrust.

The SS2 engine that was being tested is a single chamber hybrid.

Carmacks current platforms have a single chamber as well, though later versions will be multi-chambered platforms whose engines are modular. Their physical arrangement will be such that you can cluster as many generic units as required. In some of his talks hes proposed 48 or even 64 thrust chambers.

Saturn I:


Soyuz: