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Comment by globalnode | Hacker News Reader

Even if it landed perfectly how is it going to be rapidly reusable with all those tiles breaking and needing repair? Then if that problem was magically engineered-away through some sort of materials science breakthrough, it still makes more sense to me to keep your big ships in a space staging area and your smaller ones as atmospheric gophers.

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All what tiles breaking and needing repair? There was remarkably little visible damage this time around compared with previous flights.

There's no materials science breakthrough needed -- the shuttle used ceramic tiles successfully its entire service life. What's needed is engineering work, and that's what SpaceX has been doing.

You know a whole the size of a quarter can wreck the entire spacecraft and make it effectively throw away? Also, you'd want to use this many times. Making a system robust while not requiring months of refurbishment is really really hard.

The Space Shuttle had that problem because it was aluminum with a much lower melting point. It’s one of the reasons they’re using steel.

We’ve seen much larger holes than that in previous tests. Some of the control fins burned completely through.

For some of the tests, they removed a few tiles before launch, presumably to test that. Starship did fine.

coming back in one piece, and being good enough to use for 5 more missions are two very different things. For example, all existing reentry vehicles come back "fine" but they need to be completely remade to go up again.

I remember this being the same argument used against the Falcon 9 when it first stuck its landings.

"Oh, they'll need to do it 10x to be profitable!"

Now they do, as a matter of course.

Just because you defeat popular consensus of what is possible in one place doesn't mean you can continue to do it again and again. This stuff is hard.

Yes reusing falcon 9 was hard too.

Being a cynical naysay isn’t hard.

uncritically believing this design will succeed, despite having all the signs of Elon interfering and massively shifting requirements, isn't "hard" either

I doubt that. It's made of stainless steel. If it gets home safely they can patch it.

Deliberately testing its survivability with that failure mode over different parts of the vehicle has been one of the major foci throughout the entire test campaign, and it has proven remarkably resilient. That generalisation pretty much does not hold for starship.

They already demonstrated that entire tiles can be removed without wrecking the spacecraft.

The quarter thing may have been true for the space shuttle, that doesn't make it true in general.

Weren't the tiles one of the worst obstacles to quick turnaround times for the shuttle? It was something like 18 months before one could be launched again, and that's if they were in a hurry.

By the end they could turn a shuttle around in ten weeks.

SpaceX has been specifically engineering both the tiles themselves (e.g. manufacturing) and the way that are used on the ship to be much more rapidly repairable than the Shuttle.

Small ships are less efficient, especially leaving the gravity well. Thats the whole point

Could you tell me more? I suppose a heavy two-stage rocket is not optimized from the point of view of the rocket equation, but I know nothing about this field.

In short, the more stages the better to discard mass once it isnt necessary, and the larger to the better to improve the ratio of (ship+payload) to fuel.

Here is a decent summary.

https://gemini.google.com/share/121466b300c1

This is only true to an extent. Yes, a larger rocket means a better mass:payload ratio, but a larger rocket also means more mass in absolute terms, and more mass means more fuel, and more fuel means more mass, and more mass means more fuel, and more fuel means more mass, and so on. This is "the tyranny of the rocket equation", and it places an upper bound on the size of rockets that need to carry their own fuel for a given gravity well. And because the larger absolute mass of a larger rocket means more fuel, which means more cost, it relies on actually being able to find enough paying customers to fill out that payload capacity every single time. This is why, for example, despite the existence of jumbo jets (which have a better mass:payload ration than smaller planes), most passenger flights are not on jumbo jets, because there's just not enough demand on most routes.

> This is why, for example, despite the existence of jumbo jets (which have a better mass:payload ration than smaller planes), most passenger flights are not on jumbo jets, because there's just not enough demand on most routes.

Airlines used to use a hub and spoke model where it would make sense to have larger planes between hubs and smaller ones to get to and from the hubs, but consumers strongly preferred direct routing, so it didn't work out. For orbital payloads, most payloads probably do not mind too much if it takes a month or more to boost/deboost themselves to their intended orbits.

No it doesn’t matter if the payload is full or not. If they succeed in full reuse, flying on a mostly empty Starship will be ten times cheaper than flying on an F9 and that means everything will switch eventually.

If a jumbo jet was ten times more efficient than a smaller plane, they would go everywhere. If a giant pickup truck got a 100MPG, why would you take a 30MPG economy sedan anywhere?

You fundamentally misunderstand the implications of the rocket equation. It does not put and upper limit on rocket size for a given gravity. Smaller rockets would not be successful where larger fail.

Due to strucrually efficiency, larger ones suceede where smaller fail due to higher m0/mf ratio

They’ve already demonstrated they can replace all the tiles in a couple of days - even if they continue to have some fall off it won’t be an issue.

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