SpaceX Rocket Engine Explodes During Test

Sooner Boomer

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from space.com

A SpaceX rocket engine exploded Sunday (Nov. 5) at the company's test facility in McGregor, Texas, according to The Washington Post.
The explosion occurred during a "qualification test" of a Merlin engine, the type that powers SpaceX's workhorse Falcon 9 rocket, the Post reported. (The two-stage Falcon 9 has nine Merlins in its first stage and one in its upper stage.)
SpaceX has suspended engine testing while it investigates what caused the incident, which didn't injure anyone, the Post added. In a statement provided to the Post, SpaceX representatives said they didn't expect the explosion to affect the company's launch schedule.
That schedule has been pretty packed this year. SpaceX has already launched 16 missions, all of them successful, in 2017 — twice as many as its previous high in a calendar year. And all but three of these missions also involved landings of the Falcon 9 first stage, for eventual refurbishment and reuse. (During the other three launches, no landing was attempted.)
The reuse of rockets and spacecraft will slash the cost of spaceflight, leading to greater exploration opportunities, SpaceX founder and CEO Elon Musk has said.

SpaceX has experience investigating accidents. In September 2016, a Falcon 9 exploded on the launch pad during a routine preflight test, destroying the rocket and its payload, the Amos-6 communications satellite. The company traced the problem to a design flaw in one of the helium canisters inside the rocket's second-stage liquid-oxygen tank.
In June 2015, a Falcon 9 broke apart less than 3 minutes after liftoff, scuttling an uncrewed cargo run to the International Space Station by SpaceX's Dragon capsule. That accident was caused by the failure of a single steel strut inside the second stage, the company determined.
Nobody was hurt in either of these incidents.
SpaceX has several more Falcon 9 missions on tap for 2017, and the company also aims to launch its huge new Falcon Heavy booster for the first time before the end of the year.
 

Nytrunner

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I was reading that the explosion occurred during the pre-ignition LOx flow. Weird

Not like this is the first time they've had an explosion/fire/rapid-unexpected-disassembly on a stand before. They'll live
 

georgegassaway

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FWIW:

"The incident, according to the source, took place not during an actual engine firing but during a troubleshooting activity called a “LOX drop” where liquid oxygen is flowed through the engine to look for leaks. It wasn’t clear how this test led to the anomaly that damaged the engine and its test bay."

Also, this was a Merlin 1D engine modified for the "Block 5" version of Falcon-9, which is supposed to start flying sometime in 2018 (last winter, or before, they were saying late 2017). The Block 5's Merlin engine is supposed to have a little more thrust, but the biggest feature of Block 5 is that it is supposed to be able to fly 10 times without refurbishment (inspect each time, yes, refurbish, no). And supposedly after 10 flights then get refurbished to be able to fly more times. The engine MAY have been using a new component design intended to allow the engines to be reused so many times without overhaul.

Many possibilities - flaw in new design, flaw in part fabrication, flaw in assembly, unrealized risks of this "oxygen drop" test process, flaw in sequence for this oxygen drop test. Or something as basic as human error with handling/installing the hardware on the test stand or the test process (opening a valve at the wrong time, NOT opening a valve at the intended time, some sort of organic contaminant the oxygen reacted with, etc.).

At any rate, being a Block 5's engine is why the explosion, for whatever reason, does not seem to affect upcoming Falcon launches in the near-term. As those are all either Block 4's, or re-used Block 3's.

If there was some sort of design/fabrication issue requiring a lot of time to solve, I guess (?) worst-case they could fly with the currently used Merlin engine design used for Block 4, on the Block 5's for a few flights to be able to re-use the cores and start getting data on how well they are doing regarding no reburbishment, other than the engines. Then perhaps swap those engines out after the fix and perhaps modify those removed engines to Block-5 specs if it is something as "simple" a say a new turbopump component like a turbine. But that may be over-speculative, especially if this ends up being human error or a flawed testing process.
 
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cvanc

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This was an issue in, if I recall, the X-1 program. Some of the gaskets used in the LOX path - I think it was the actual pumps, but perhaps elsewhere too? - were made of leather.


That was my immediate thought when I heard what happened. Oxygen is very sensitive to that sort of thing, and I suspect LOX even more so.

Something will be learned, which is a good thing.
 

georgegassaway

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A really great article in Smithsonian's Air & Space Magazine, about building the Saturn-V:

https://www.airspacemag.com/space/we-built-saturn-v-180964759/

Mostly great stories, but there was this sad one, about how a worker at a Test Stand was lost due to a Lox and organic interaction while the worker was walking around.

We lost a man on the test stand because we had a liquid oxygen leak and the liquid dripped on the flooring of the test stand. The guy came along and saw it. It had built up into like a little icicle and he kicked it and it blew his leg off. He had on rubber shoes, which had some oil or something on them, and oil in contact with cryogenic is just disastrous.

The other ways there could have been an organic material ,that was NOT contamination, could be a real leak, that allowed Lox to get into places it's not supposed to be. Or if there was some RP-1 residue inside the engine's spray head or combustion chamber. Which would "sort of" be organic contamination in the sense that for any test that might allow the Lox to make it that far, they'd never want any traces of RP-1 left. But I think of contamination more in the sense of some organic substance elsewhere, that should be cleaned off or somehow got into a location it was never supposed to be.

Rumors the last few hours lean a bit more towards some sort of testing process error (I take that as not necessarily human error, could be badly designed test procedure or procedure with more risks than they realized). But no idea if that's rooted in some real knowledge, or just rumor.
 
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Nytrunner

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This was an issue in, if I recall, the X-1 program. Some of the gaskets used in the LOX path - I think it was the actual pumps, but perhaps elsewhere too? - were made of leather.

That was my immediate thought when I heard what happened. Oxygen is very sensitive to that sort of thing, and I suspect LOX even more so.

Something will be learned, which is a good thing.

I don't buy the contamination. They have a pretty strict GOx/LOx cleaning/QA process, and specific hardware for systems with oxidizers involved.

Unless someone slipped up or forgot the Krytox.

Everyone (even X-space) is susceptible to human error. Like I said, it's not they're first rodeo blowing an engine lol
 

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