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Comment by mabbo | Hacker News Reader

For those who don't obsessively follow SpaceX:

SpaceX is working on three projects right now. #1- Falcon Heavy, strapping three Falcon 9s together to make a super awesome rocket. #2- The BFR. All over the news lately, going to be a humongous rocket that does New York to Sydney in under an hour, or take humans to the Moon or Mars.

And #3, they are working on what's being called "Block 5", the supposedly final upgrade to the Falcon 9 rocket, including upgraded Merlin engines. These would make the rockets just that much more powerful, increasing payload sizes on both Falcon 9 and Falcon Heavy launches.

So, this is probably one of those new Merlin engines. And it exploded. Which is going to delay Block 5. Damn.

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As the article reports it was a Block 5 Merlin (aka the last Merlin upgrade). I don't believe qualification has started yet on Raptor but that would seem to be the logical next engine to qualify after the Block 5s.

That it exploded is oddly a good thing according to friends at JPL. They say that when ever there is a catastrophic failure like this it forces a deep review and root cause analysis which invariably adds additional understanding and depth to the design. Knowing what can cause an engine to blow up, and knowing you have designed around it, is a good thing.

That's how I think when relatively complex programs I've written blow up (blow up = user term for job failing). I expect them to blow up during testing. The errors are then corrected and the code is also reviewed to determine how the error slipped by to begin with. If the programs work without any noticeable errors, the code review does not happen and there's a much greater likelihood of subtle errors slipping into production.

I don't think you can be certain it's a newer Merlin engine OR that it will delay Block 5.

They do acceptance testing of all their engines, even the current iterations. They've launched literally hundreds of these engines, with multiple tests per engine (and, as an aside, a design for Falcon 9 that is able to survive an engine failure).

They test multiple engines per week, and have the capacity for multiple times that, so losing a test cell for a few weeks need have no impact on the schedule for Block 5.

My take is that this will have essentially no impact on SpaceX's schedule.

Engine failed during qualification testing, not acceptance testing - so it's a new design.

If you don't occasionally blow an engine up on the stand you are either not testing hard enough or not pushing the limits hard enough.

What's interesting is that updated info indicates it happened before the engine (which was a block 5 engine, as you say) was ignited, when they do a "LOx drop" test, basically running liquid oxygen through it to test for any leaks: https://arstechnica.com/science/2017/11/an-experimental-spac...

It may mean they had a simple FOD (foreign object debris) or contamination issue, not a design problem. Powerful oxidizers like liquid oxygen can make contact explosives out of all kinds of organic materials.

Stuff that you normally don't think of as flammable -- like hunks of structural metal -- burn quite nicely in the presence of liquid oxygen. So stuff that burns well, burns REALLY WELL in the presence of LOX.

Oh of course. Test to failure, why didn't that occur to me with respect rocket engines? Thanks for the insight.

Move fast and blow shit up (literally)?

The article has been updated. It was a Block 5 engine, and SpaceX will suspend testing of Block 5 engines until the accident investigation is complete.

>#2- The BFR. All over the news lately, going to be a humongous rocket that does New York to Sydney in under an hour, or take humans to the Moon or Mars.

Does BFR happen to stand for "big fucking rocket"?

Yes. This is from the same CEO who wanted to name his first 3 models of car "S, E, and X" (the 3 was going to be the model E, but renamed due to ford's trademark).

And the one after that will be Y.

I always tell people that BFR stands for "Big Rocket." It's more fun to let them fill in the blank.

Well, I never! How crude! I mean just poo-poo on this sort of thing and anybody amused by it!

Don't forget the Model Y. (Basically a crossover version of the Model 3. )

Ref: https://electrek.co/guides/tesla-model-y/

Also the barges "Read the Instructions" and "Of Course I Still Love You"

I wish people would take notice... Too often, I see creative/meaningful/evocative product and company names criticised with this sort of I'm-not-complaining-but-other-will-thinking.

Yes. In polite company, it's "Big Falcon Rocket," but Elon has been perfectly clear about what it actually stands for.

I think publicly they say things like "Big Falcon Rocket".

It comes from the "BFG" from the original Doom games.

Edit: fixed... was Doom not Quake :P

Ahem, the BFG 9000 was from Doom.

Quake II and Q3A did have a BFG10K, though.

Is #4 test firing a full size Raptor a possibility?

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