Combining the second stage and the capsule? A Reuseable spacecraft concept? (Updated)

[Kryten]

Have you seen any other governments buying flights from private operators?

Yes, Russia. RKK Energiya is a private company (albeit 38% owned by the government), at least for now.

[Nibb31]

Yeah, well... they don't seem to be doing away with a LES any time soon either.

The point is, a LES is going to be a requirement for the foreseeable future, so you can't just wave it away. You are going to need some way to abort safely, and a separable capsule seems to be the best way to do it.

A Dragon V2 with an extended fuel tank and reworked engines as I described above might just be able to pull it off.

Edited November 17, 2014 by Nibb31

[Beowolf]

If the rocket engines can be made/proved to be reliable enough...

Yeah, but that's kinda like starting a sentence with "If we had warp drive...". We don't have rocket engines that reliable, and barring miracle breakthroughs in nanotech, won't have them in the near future. Reliable enough to carry passengers without an escape system is four or five orders of magnitude beyond the most reliable engines ever built. That'll take tech like building an engine atom-by-atom out of synthetic diamond.

We've been building ocean-going ships for thousands of years and those still aren't reliable enough that we skip the escape system.

[Bill Phil]

Yeah, but that's kinda like starting a sentence with "If we had warp drive...". We don't have rocket engines that reliable, and barring miracle breakthroughs in nanotech, won't have them in the near future. Reliable enough to carry passengers without an escape system is four or five orders of magnitude beyond the most reliable engines ever built. That'll take tech like building an engine atom-by-atom out of synthetic diamond.

We've been building ocean-going ships for thousands of years and those still aren't reliable enough that we skip the escape system.

The shuttle didn't have a LES system. It only had a fatal launch failure ONCE, out of 135 flights. That's reliable, and that was 70s tech. Sure it was improved, but what if we built it with modern tech? It would be EVEN more reliable.

[Kryten]

The shuttle didn't have a LES system. It only had a fatal launch failure ONCE, out of 135 flights. That's reliable, and that was 70s tech. Sure it was improved, but what if we built it with modern tech? It would be EVEN more reliable.

Just because something might be old doesn't mean it's been bettered. 70s or not, the SSME is the US state-of-the-art.

[Bill Phil]

Just because something might be old doesn't mean it's been bettered. 70s or not, the SSME is the US state-of-the-art.

Well, that's primarily due to the fact that the US hasn't had much of a budget for spaceflight, and so engine development had to be sacrificed.

There's always room for improvement.

[NERVAfan]

Have you seen any other governments buying flights from private operators?

I was thinking in terms of selling flights to governments with significant space agencies but without an in-country manned spaceflight capability - India, Japan, etc. I don't think there is currently anyone for them to buy manned flights from.

[NERVAfan]

Yeah, but that's kinda like starting a sentence with "If we had warp drive...". We don't have rocket engines that reliable, and barring miracle breakthroughs in nanotech, won't have them in the near future. Reliable enough to carry passengers without an escape system is four or five orders of magnitude beyond the most reliable engines ever built.

That's an incredibly high standard for acceptable safety - assuming roughly 1% chance of fatal accident per Space Shuttle launch, four or five orders of magnitude better would be about 1 in 1 to 10 million launches.

The Space Shuttle's level of safety was IMO unacceptable because it was seen as 'routine'. For a nation just starting manned spaceflight, or for doing something genuinely new like going to Moon/Mars, 1 in 100 chance of death is not that unreasonable (Antarctic exploration in the early 20th century was quite a bit worse than that

EDIT: Anyway, you wouldn't have to sacrifice all launch-escape capability. You could still escape from a first-stage failure like the recent Antares one, and some 2nd stage failures would allow a return, too.

Edited November 17, 2014 by NERVAfan

[Kryten]

I was thinking in terms of selling flights to governments with significant space agencies but without an in-country manned spaceflight capability - India, Japan, etc. I don't think there is currently anyone for them to buy manned flights from.

Only Japan have anywhere they'd want astronauts to actually go to (their ISS module), and they currently receive flights from the US government for contributions to the ISS.

[NERVAfan]

Only Japan have anywhere they'd want astronauts to actually go to (their ISS module), and they currently receive flights from the US government for contributions to the ISS.

I imagine there is a price point at which they would be interested in buying flights (same for Brazil, South Korea, Israel, etc.) Depends how cheap flights on the reusable vehicle were.

[Kryten]

Why would they? There's no national prestige to be gained from buying services, and there's very little science suitable to be done in a crewed capsule.

[Aghanim]

For people thinking about reentering nose down:

How about G force load? Having upside down G force isn't good for the crew, humans are less tolerant of negative G compared to positive G

[Sky_walker]

If the rocket engines can be made/proved to be reliable enough, maybe it wouldn't have a launch escape system. Depends who is building it and what risk they are willing to accept.

No. There's no 'engines are reliable enough to ignore escape system'. Also: Engines are not the only thing that might fail during the launch.

I imagine there is a price point at which they would be interested in buying flights (same for Brazil, South Korea, Israel, etc.) Depends how cheap flights on the reusable vehicle were.

No, it does not depend on how cheap the flights are. It depends if there's any destination for astronauts to go to, if there are any objectives for such mission, and if there are some alternatives.

Note that space agencies potentially most interested in taking astronauts to the ISS make it through exchange programs (like ESA who got several astronauts taken to the ISS and Mir in exchange for their contribution to the station and/or by giving hardware to NASA) and aren't really interesting in picking up random flights just because they can.

Why would they? There's no national prestige to be gained from buying services, and there's very little science suitable to be done in a crewed capsule.

In theory there's a prestige to by gained by sending a first astronaut from your country - see Malaysian Angkasawan program. But it was widely criticised and a list of countries potentially having money and political will to repeat the same stunt is most likely empty.

Edited November 17, 2014 by Sky_walker

[Nibb31]

I was thinking in terms of selling flights to governments with significant space agencies but without an in-country manned spaceflight capability - India, Japan, etc. I don't think there is currently anyone for them to buy manned flights from.

But why would they want to do that? The whole point of a national space agency is to subsidize a domestic space industry and to gain access to domestic space technology.

This is why international cooperation works with barter agreements and not upfront payments: ESA or JAXA get rides to the ISS in exchange for providing hardware that was paid to European or Japanese contractors. Everybody wins.

Buying tickets from a foreign provider misses the whole point. There is little prestige to be gained by it. Just look at NASA.

[DerpenWolf]

Added some more stuff to bottom of the original post to consider.

If you look at the spaceX animations, the second stage reenters headfirst to protect the engine

Haven't seen anything on their plans for recovering the second stage, mind sharing some links?

Edited November 18, 2014 by DerpenWolf

[NERVAfan]

No. There's no 'engines are reliable enough to ignore escape system'.

I'm not sure I agree. Let's say you have simple, pressure-fed engines, and a one engine rocket, and it's reusable, so you test fire it 10,000 times.

And it depends on the risk you are willing to accept, anyway. Not all organizations will be as risk averse as NASA currently is.

[Albert VDS]

You could still make the capsule detachable from the 2nd stage, which should be a requirement if something like this would be made.

The down side is that it would add to the weight of the whole rocket.

Spacex' approach is much better, a classic 3 part rocket with reusability added to it.

[Nibb31]

Haven't seen anything on their plans for recovering the second stage, mind sharing some links?

It's in their old SpaceX-Muse video from 3 years ago:

Of course, that's all pretty outdated now. Falcon 9 and Dragon have changed a lot since this video was published, and reusing the second stage is still only a long-term goal. It's orders of magnitude harder than reusing the first stage.

[Starman4308]

I'm not sure I agree. Let's say you have simple, pressure-fed engines, and a one engine rocket, and it's reusable, so you test fire it 10,000 times.

Not a valid test: that cannot account for probability of manufacturing defects. You would need to test a large number of engines to be sure of that reliability, and that would be hideously expensive.

[NERVAfan]

Not a valid test: that cannot account for probability of manufacturing defects. You would need to test a large number of engines to be sure of that reliability, and that would be hideously expensive.

I am talking about a reused vehicle, not a classic expendable rocket. Each vehicle would fly hundreds of times and the number of vehicles would be small. So you could test fire each vehicle's engine a couple of hundred times too.

[NovaSilisko]

SpaceX already has a plan to reuse the second stage. Its just like your plan except it doesn't keep the capsule attached.

They've more or less decided not to pursue second stage recovery with Falcon 9, because most flights go to geostationary transfer orbit, which makes recovery exceedingly difficult (enough so that they'd have very little payload, which defeats the purpose of sending the rocket there in the first place)

The video spacex presented is very outdated, and the second stage recovery presented there was just a rough concept.