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Comment by CommieBobDole | Hacker News Reader

I hope it goes well, but I'm concerned that they've never done a test flight or a full-duration 33 engine static fire on the first stage booster. SpaceX has always been about real-world testing and rapid iteration based on the (often catastrophic) results of that testing. I worry that the lack of testing is due to a business desire to avoid the (stunning) cost of building and losing 33 Raptor engines on each failed test article, rather than an engineering judgement that such tests are not needed.

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>I worry that the lack of testing is due to a business desire to avoid the (stunning) cost of building and losing 33 Raptor engines on each failed test article

Uh, what? They are going to lose them, and it's fine because it's not a stunning cost at all. If everything goes absolutely perfectly here, the engines are all going straight to the bottom of the ocean. There is no effort to save anything, they're being cautious with the part that actually matters (the ground infrastructure). Minimum goal for that same reason is getting a thousand feet above the tower or whatever it was before it explodes, again so that ground infra is ok. Like Starship overall, Raptors are designed to be cheap and mass produced. Long term it's definitely very important to economic viability to recover SH, recovered SH and expended SS (if it took awhile to nail down reentry say) would be a fine MVP, expended both would not, but a few tens of millions of dollars out of a multibillion R&D effort is fine at this stage. My understanding is that the booster they're launching is indeed already obsolete, because it doesn't have the new full electric+torch ignition system. They've been building up to this steady and deliberately, and there is no sign of a rush or that they've made this decision for any reason but that they're ready to give it a go again. Their plans of course have all been thoroughly reviewed by government as well.

So this is kind of an odd take? They've already been dealing with 27 engines in F9H, this is hardly their first rodeo. F9 is already arguably the most reliable rocket ever. These aren't amateurs.

> I'm concerned that they've never done a test flight or a full-duration 33 engine static fire on the first stage booster

This _is_ the test flight

Every engine has been through a full cycle test at their engine facility before being installed. This is the case for all of SpaceX engines from Falcon to Starship. The first trip to space is not the first full duration fire

To be fair, firing 33 engines at the same time when they're a meter or two apart is a pretty different environment. But as others said and I agree, this is that test.

> firing 33 engines at the same time

They've gotten up to 31 at an unspecified less than full throttle

https://www.cnn.com/2023/02/09/business/spacex-static-fire-s...

Well, let's hope it goes better than the N1.

I'd assume it would go better than a rocket that was entirely designed on physical paper.

>I worry that the lack of testing is due to a business desire to avoid the (stunning) cost of building and losing 33 Raptor engines on each failed test article, rather than an engineering judgement that such tests are not needed.

Determining whether it is worth risking 33 Raptor engines in a static fire is an engineering decision.

There is no such thing as multi-objective optimization hence engineering decisions = engineering decisions = decisions

They did a short duration static fire, they seemed to do a lot to keep it held down at ~50% throttle, full LOX tank, just enough methane for combustion.

It is probably impossible to have a full thrust or duration static fire on the existing launch mount, or any?

Well, they'll get their test data if they fail and they'll get it if they don't :-)

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