5 ms·
Depends on what kind of test that was supposed to be. If they pumped it until it explodes it would be a kind of test (also called experiment) where it makes se
by lmilcin 7y ago
Depends on what kind of test that was supposed to be.
If they pumped it until it explodes it would be a kind of test (also called experiment) where it makes sense.
If you design something with a margin of safety, then pump it to working pressure and it blows, then it means you made a mistake. If you made a mistake it shows you don't know what is necessary to design a rocket (yet).
Seriously, they don't build skyscrapers or bridges and leave for 5 days to see if they topple to prove the design was correct.
- DennisP 7y agoI think SpaceX has proven they know how to design rockets. But they are newcomers to building rockets from welded steel.
- walrus01 7y agoIt is my understanding that the pressure vessels are carbon fiber composites. The skin is steel.
- gpm 7y agoThe skin is the pressure vessel, double walls are a waste of valuable mass. They gave up on carbon fiber awhile ago. *I think they still use small composite overwrapped pressure vessels for fluids they need less of than CH4 and O2, just referring to giving up on carbon for the main tanks.
- nwallin 7y agoDo you have a source? My understanding is that the skin is the pressure vessel. The reason for going with stainless steel at all is because it maintains integrity at high temperature. Carbon fiber does not. So a stainless steel combined heatsink and structure can maintain integrity at 1000C or whatever, while carbon fiber+ceramic heatshield will need to hold temperatures below 400C or whatever. And even though the fiber structure is much, much lighter, the amount of heat protection required is massive. And the stainless steel "cheats" by performing double duty. And you get a second free lunch because the heat protection requirements are slimmer. It wouldn't be the first time I've been wrong today though. Nor the second.
- walrus01 7y agoApparently I have not been following this as closely as I thought I was. This 12 meter diameter tank is from 2016. Not part of current design. https://everydayastronaut.com/stainless-steel-starship/ https://everydayastronaut.com/stainless-steel-starship/
- baking 7y agohttps://everydayastronaut.com/stainless-steel-starship/ https://everydayastronaut.com/stainless-steel-starship/ Edit: "So in summary. SpaceX chose stainless steel over carbon composites because it’s about as light, it can handle higher temperatures which means less heat shield is need, which then makes it lighter, it reflects heat which means even less heat shield which again makes it even lighter, it’ll be cheaper and quicker to build AND it’ll look FREAKING AWESOME."
- gaius_baltar 7y ago> But they are newcomers to building rockets from welded steel. AFAIK everybody is.
- Gravityloss 7y agoAtlas was steel. The first US ICBM and an early space launch vehicle. To this day, the Centaur hydrogen upper stage with RL10 engine is steel. Balloon tanks. They inspired SpaceX heavily.
- Retric 7y agoRockets are designed to have a vastly lower margin of safety. If they never fail in testing that’s a sign you’re over engineering it and sacrificing cargo capacity, which is a bad thing. That said, these failures should be uncommon.
- CydeWeys 7y agoStarship needs to be reusable dozens of times, with no refit between launches (only refueling). Fuel is cheap; the vehicle needs to survive. It also needs to be reliable enough to carry people. They're not using razor-thin safety margins on it.
- brmgb 7y agoFuel is not cheap. Fuel is heavy and payload reduction is money lost.
- inetknght 7y agoFuel is cheap. Spaceships are not.
- JshWright 7y agoFuel is very cheap. SpaceX has built their whole business around the idea that it's worth trading payload for re-usability.
- outworlder 7y agoFuel is cheap on a monetary basis. _Lifting_ that fuel is NOT CHEAP. See also, the rocket equation.
- ethbro 7y agoBut the primary cost of lifting fuel (if you have a reusable rocket) is fuel. Leaving us back at cheap. But we're essentially arguing whether max payload per launch or payload efficiency to orbit is more important.
- outworlder 7y ago> If you made a mistake it shows you don't know what is necessary to design a rocket (yet). Yeah, sure SpaceX doesn't know what's necessary to design a rocket.
- larnmar 7y agoSeems like the difference between unit tests and integration tests.
- AYBABTME 7y agoSkyscrapers have been built again and again, and they have much different constraints. Starship Mk1 is the first of its kind.
- playa1 7y agoI expect this was more likely a manufacturing mistake. It was assembled night and day under a very tight deadline.
- tus88 7y agoBoeing intentionally snaps of the wings of prototype aircraft to find the breaking point/prove the margin of stress.
- yread 7y agoNo, they don't. They load it to 150% of max design load. Sometimes they keep bending it until it snaps (777) and sometimes they don't (787 - no one wants to clean carbon fibre mess). Sometimes it snaps before it's reached and it's ok (airbus a380).
- iamgopal 7y agoAt least the pump is working and generating pressure.
- azernik 7y agoThis and the Mk2 prototype in Florida are mostly experiments with manufacturing processes; I would not be surprised if there were a reliability problem with their methods that weakened the product.
- elihu 7y ago> Seriously, they don't build skyscrapers or bridges and leave for 5 days to see if they topple to prove the design was correct. Perhaps a better analogy is carving a violin top. Skyscrapers and bridges can be overbuilt without destroying their utility, but a violin has to be as thin as possible without breaking if you want it to function well as a violin.