Space and Science BS Thread

I definitely got that feeling too. That was some of my rationale for coming down for this attempt. I really thought the would complete the countdown regardless of the issues based on the tone of the press conferences. So I’d either see an awesome successful liftoff or a specular failure.

 

Everyone down the line was saying “we agreed on thus and such” as if it was a committee with no one in charge. I expect on or more of them said wtf are we doing here? This isn’t a cross-your-fingers-and-hope-for-the-best situation. We need to do this right, period.
Problems with the QD and anything related to the Mobile launch structure need to be corrected before Bechtel repeats those errors on ML-2 for Block 1B and Block 2.

 

I really think NASA(ie Nelsen) needs to relax and let go of artificial priorities regarding Artemis 1 and Starship. Raptor II shows signs of being a great engine that isn’t quite finished and needs a bit more reliability before 33 of them can be relied on to any extent. The only way Starship beats A-1 to orbit is if A-1 royally screws the pooch. Dont rush. Don’t take your time, take THE time to get it right.

 

I think you're right about the Raptor 2s. Musk's drive to simplify means they changed the the way they ignite the engines. Maybe they should have left that for the Raptor 3s.

 

I don’t claim any knowledge of rocket engine design but when I see both Starship and Super Heavy have to swap out engines in the same week when they have more than a hundred to choose from and they’ve only just started multiple engine static fires it’s disconcerting. One out of three projects to 11 possible failures(more if you include Starship). They had their pick of all the engines in house aside from those exposed to the spin prime explosion (still more than a hundred). Either the individual test firing isn’t exposing a flaw or the engines aren’t holding up after that or it’s something else. Maybe they know of an issue and are using the static fires to acquire data?

 

Heh.. idk, I think 7/24 has a pretty good shot.

 

While Musk hasn't said that much about the new Raptor design besides "We made it simpler"; they are testing each and every engine at McGregor. I would imagine they are finding faults with the Booster internal systems and that is causing the faults. I don't think the explosion was any fault of Booster or it's systems.

 

What’s disconcerning? Raptor2 is a never before flown engine based on a White Whale design that’s being refined to withstand multiple launches. These engines can be swapped at the pad in hours.

I’ll stop making comparisons with the competition because it’s just embarrassing at this point.

 

Jupiter from Juno…

 

https://twitter.com/jennyhphoto/status/1566437275986284544?s=21&t=G8VNWFwZGs7cIPqFulHtaA

 

I’m not comparing them at all. But given that every single engine was tested before being installed so they had the pick of the litter for all 39 engines even if they swapped out all 33 after the spin prime boom. They did 2 single engine tests of the outer 20 then mounted the inner 13 and one out of 3 failed on the booster on the very first multi-engine static fire and one of 6 on Starship was also replaced around the same time. I’m not saying it’s a bad engine but it hasn’t demonstrated much in the way of reliability yet. What’s disconcerting is not knowing whether it’s a manufacturing defect, design flaw, or what. I have confidence that it will be resolved in a timely manner whatever the issue is though.

 

Just the number of Raptor2s developed is encouraging to me. The pace SpX interates is also an encouragement. I'm sure they're working on testing out groundbreaking alloys and eventually will meet their goals for reusability. I think for now they're willing to sacrifice reusibility for dependibility on this never seen before, cryogenic full-flow staged-combustion-cycle rocket engine. (Caveat - my knowledge of such things comes from Wiki and Tim Dodd so take it FWIW..) I'm also sure they're planning on not being the cause for missing a 2025 landing date though the lack of Lunar Starship in official NASA materials could be telling

 

What would constitute an acceptable level of reliability for you at this stage? 100% success of SF for every engine on every SF?

This is experimental tech on a rocket the size of which hasn't been seen since Atlas V! And they had their own fair share of engine/rocket failures in the beginning of the program and all the Mercury launches.

 

But we don't know why any engines were removed. They could have found a loose bolt, and not knowing whether someone forgot or the static fire loosened it hey decided to replace it with one of the 100 engine they got laying around and then tore down the loose bolt engine to inspect their new rocket engine design.

As for raptor 2's simplification. That was done for reliability. They removed a ton of prototyping sensors. Every hole in the engine block is a new potential failure point, especially with the pressures they're dealing with. Then there is removal of the flanges. Flanges are bad, they leak. And you can't just go out to the pad and tighten the flange bolts a little more while they're under cryo temps and pressures. Replacing them with a welded joint however means you can literally x-ray the weld for defects.

Then there is the fact that raptor 1 is a true prototype engine. This means almost every component on it is designed to be tested, removed, inspected, revised, and tested again. Raptor 2 is a flight engine. The ability to remove individual components creates more risk than benefits.

 

Hmm, I get the feeling I’m coming off as alarmist when that’s not the case. I expect problems but the noise I hear(not here but elsewhere) is mostly how Starship is going to fly sooner rather than later and the ramp up in static fires will lead to that without any hiccups and that’s not realistic to me. With the success of F9 and multiple secure contracts Spacex is far better situated than most of the industry but in spite of each example of how their innovations work out eventually there ARE problems. As the amount of infrastructure increases the risk associated increases exponentially. Blowing up something on takeoff or landing now isn’t the same as when it was just a concrete pad in a mostly barren beachfront property. It’s not the fact that one engine misfired but that two had problems in a matter of a few days so early in the program and Elon himself walking back the timeline that has me dialing back my expectations. Given how much work has been done to the OLM it’s conceivable the problem lies there but that doesn’t explain the Starship vacuum raptor. Eventually they will figure it out, I’m confident of that but while the tests leading up to SN 15 were spectacular and enormously helpful that kind of learning experience has much greater consequences than previously. Has there even been a hop test or suborbital test using raptor II’s? Didn’t SN15 use raptor I’s? We’re up to SN 24 now and with the HLS contract I’d think some further testing of the takeoff/landing capabilities using the new engine are in order. Maybe that’s why they’re building some without tiles or fins since the current plan is for a skeleton version most similar to this. That testing would seem to me a more natural progression leading up to a full up 33 engine test and orbital launch since it can be done a safe distance from the Mechazilla, OLM, and tank farm.

 

I kinda wonder if they’re taking engines off to dissect them and make sure they’re not seeing new internal failures/damage as they add to the number of engines firing. If I were hardware rich, I’d love to gradually crank up the number in each firing, pulling a few each time to check for any hidden damage.

 

It depends on what the next step is. My concern with reliability isn’t about today, tomorrow, or next week but how many engines they’d fire simultaneously or whether they’d attempt an orbital launch if this proves to be an issue. They’re not risk averse but they can’t afford to be or even appear to be foolhardy when it comes to launching SH.

 

Yes that makes good sense but one did abort. Hopefully they’ll learn something from that one or it may take a succession of SF’s with that particular problem to identify it. It’s still early and knowing something went wrong doesn’t guarantee you nail the problem first try. All of these engines have been tested on a stand so what has changed? The pace and changes to the OLM as well as the spin prime system for the inner 13 leave the question pretty wide open. It might not be an engine issue at all. The abort may have stemmed from inadequate turbo pump pressure caused by the onboard tanks.

 

Ok, I think I begin to see your point. And, to be honest, I don't consume news about SpaceX from the mainstream media. Most of what I glean and piece together is from Tim Dodd, Scott Manley and the team at NASA Space Flight. So, I don't hear the "click bait" news pieces about "SpaceX may get to the Moon before SLS!!1!" and I already know that to be false.

I do think we tend to forget how many RUDs F9 went through before they got their programming ironed out. And even once they were able to get to orbit consistently, they still lost many rockets to improper landings.

We're going to see this with B7 and S24. They're not going to be reused. B7 will put S24 into orbit and we may see an attempt to hover B7 over the surface of the Gulf. S24 will release 5-10 Starlink V2s for proof of concept and they may try a RTLS with S24 to try to catch it. That's probably not going to go well.

All that being said, I do think that Stage 0 has been built well enough to handle small RUDs, and SpaceX and Musk won't take us to being an interplanetary species without a few "hiccups" along the way.

 

I want them to persevere despite the odds but the ships and boosters look so flimsy you can see the dents and out of spec shapes. What will happen to B7 at max Q when the tanks are no longer full but still have to support the full weight of SN24 as well as the aerodynamic pressure? I can’t answer that but I’ll breathe a big sigh of relief at that point. My questions regarding the engines pale in comparison to those of the booster and are more on par with the ships which stack that while still new have at least flown so any growing pains there are just that. The stuff I’m saying is obviously my gut feeling and not any detailed analysis so it doesn’t bother me to be disagreed with. It’s more due to my own impatience and having to wait on results that I even do this. Much of my work involves solving problems and making disparate issues come to a resolution so anticipating problems is nothing new, nor is seeing it through and solving them but like any fan of a sport it’s hard to be powerless on the sidelines. This is just a speculative outlet for that.