Red Moon: The Soviet Moon Program

[PeZook]

Did you just totally miss that the shuttle never orbits higher then about 400km, while Saturn V boosted that payload to the freaking moon?

No, this is patently false: while the SIVB made it to the Moon (sometimes) it was always violently crashed into it and had almost no fuel left. What made it to Moon orbit out of the original 3000 tonnes were about 45 tonnes composing of the CSM and LM.

What was deposited on LEO was a CSM spaceship, the lunar lander and the final SIVB stage with enough fuel for trans-lunar injection, or around 120 tonnes.

Efficient the shuttle is not. Nothing that puts so much spacecraft mass into orbit, only to bring it all back after two weeks could be. In fact the payload to an equivalent orbit is only about 25% that of Saturn V.

Yes, the useful payload of the Shuttle is small (duh). I was talking about the launch vehicle (granted, a hazy concept with the Shuttle), not the entire system. And what ends up in orbit after launch masses 112 tonnes,however you look at it.

Counting the orbiter as all payload is total nonsense, since it holds you know, all the engines that burn the fuel from the external fuel tank.

So? Everything that flied to orbit ever took engines with it. The orbiter is simply the second and third stage plus the retropack all rolled into one.

[Sea Skimmer]

No, this is patently false: while the SIVB made it to the Moon (sometimes) it was always violently crashed into it and had almost no fuel left. What made it to Moon orbit out of the original 3000 tonnes were about 45 tonnes composing of the CSM and LM.

That's what I meant, sorry if that’s unclear, but the entire point is the Shuttle Can't get ANYTHING to the moon at all. It would at best be able to transport another rocket stage as its payload, to boost a much smaller load to the moon. It cannot be more efficient iuf it can’t even do the damn job.

What was deposited on LEO was a CSM spaceship, the lunar lander and the final SIVB stage with enough fuel for trans-lunar injection, or around 120 tonnes.

And the Shuttle can't even try to do this on its own, so how's this make the shuttle more efficient?

Yes, the useful payload of the Shuttle is small (duh). I was talking about the launch vehicle (granted, a hazy concept with the Shuttle), not the entire system. And what ends up in orbit after launch masses 112 tonnes,however you look at it.

Right, so orbital height and payload just don't matter in a comparison of efficiency, that’s a funny way of looking at things. Epically since you seem to reject the idea of the SIVB reaching the moon 'counting' because it can't enter an orbit and yet now orbiting dead weight engines to a low and soon to decay orbit does?

[PeZook]

That's what I meant, sorry if that’s unclear, but the entire point is the Shuttle Can't get ANYTHING to the moon at all. It would at best be able to transport another rocket stage as its payload, to boost a much smaller load to the moon. It cannot be more efficient iuf it can’t even do the damn job.

Huh? I'm talking about the launch vehicle being efficient. Yeah, it delivers a huge spaceship instead of two little spaceships+fuel and engines for a Moon trip. The huge spaceship still has similar mass to the little ones and their fuel.

And the Shuttle can't even try to do this on its own, so how's this make the shuttle more efficient?

Because it does 112 tonnes with 2000 tonnes of launch mass, while the Saturn V did 120 tonnes to a very similar orbit with 3000 tonnes of launch mass? The Shuttle can actually go higher than a Moon Apollo mission before TLI.

Right, so orbital height and payload just don't matter in a comparison of efficiency, that’s a funny way of looking at things. Epically since you seem to reject the idea of the SIVB reaching the moon 'counting' because it can't enter an orbit and yet now orbiting dead weight engines to a low and soon to decay orbit does?

I think we're talking about two different things here. I'm talking about efficiency of the engines themselves (the launch vehicle, which in the STS is composed of the SRBs and the SSMEs on the orbiter), while you're talking about the entire system. Of course the entire system is inefficient, but only because of what it puts up on orbit, which is simply an engineering choice.

As for orbital height, the shuttle can go as far up as 400 kilometers, so it can actually fly its heavy ass far higher than pre-TLI Apollo orbit.

[erik_t]

NASA's little white lies cost both superpowers big time. I remember reading the space shuttle boosters were built in segments because if they were built in one piece, they'd be too big for multiple companies to manufacture and then transport across multiple states to be assembled (according to this list, 19 different companies in 13 different states), and this diffusion was vital to get the program approved; we all know what this did to the Challenger. Then there's the fact that no escape pod or other emergency egress system was built because the cost overruns meant there was no money to design and test such a system; we all know what this did to the Challenger and Columbia's crews.

Point of fact: Modern solid rocket technology would not allow the casting of full-length RSRMs. It's a geometric impossibility - there is a whacking big steel core that sits inside while you cast, with big fins at the front and a larger diameter at the back. It won't come out in either direction.

Transportation across multiple states is kind of a fact of life when you consider that the only companies up to the task, (then) Thiokol and Hercules (now both part of ATK) both happened to be based in Utah. Not that it much matters, since you'd need to build the things literally within a few dozen miles of KSC to be able to transport the full-length motors. Oh, and that whole region is populated, unlike northern Utah. Hmm. May have to repopulate some folks with eminent domain spam. Oh yeah, we were originally going to launch out of Vandenberg. Two identical rocket factories then. Urh.

As for your freakout about joints, they would still have been necessary for the upper and lower caps, and would have been sealed in the same manner.

[MKSheppard]

Not that it much matters, since you'd need to build the things literally within a few dozen miles of KSC to be able to transport the full-length motors. Oh, and that whole region is populated, unlike northern Utah.

Link

What about the Aerojet plant that they built for the huge 260 inch monolithic motor; they actually fired one, and built a on-site mixing plant to pour the propellant into the casing. It was also right on a barge canal, allowing it to be barged to KSC easily...

[erik_t]

That's interesting, and I was unaware of it. That leaves the issue of transport to Vandenberg, of course, as well as the serious issue of possible case failures. In my considered and reasoned opinion, trying to get a flight-weight welded motor casing down to weight is a much bigger danger than the joint system (which in fact worked and performed as designed). At best, you've introduced a huge production bottleneck and cost akin to manufacturing submarine hulls, and you accept a substantial performance hit due to the welded case. At worst, you have to manufacture a new one each time, because the difficulty of inspecting those welds post-splashdown is prohibitive.

One of the many unsung virtues of the then-Thiokol (R)SRM design is the fact that it is literally 100% weld-free. This means that the metallic microstructure is much better controlled and understood, everything being forged in a single piece. This saves weight and inspection time/money.

I suppose it'd be possible to try to do this with a monolithic motor, but I don't want to imagine the cost of the forging.

The other issue with a monolithic cast is that defects can junk a whole motor instead of one segment. Air bubbles and voids of any appreciable size are a go/no-go level of choice. Assuming a constant void likelihood per volume, a monolithic motor will have several times the number of rejects. In practice, the void probability would be somewhat higher for a monolithic cast. Note that not only is this true for casting, but also the several layers of insulation application.

After all that, it's not obvious that monolithic motors are any safer. AIAA-2005-3793 is a useful source of information on solid motor failures. Of note, the Japanese have had 8 solid motor failures in 69 launches (about 11.5% failure rate); these are monolithic motors. The overall solid rocket motor failure rate is 16/574, about 2.8% (this is per-launch, not per-motor). The STS solid rocket subsystem has experienced one failure in 123 launches, a rate of 0.8%.


Monolithic motors sound like a no-brainer, but they present some very serious manufacturing challenges for dubious gain. Considering that the Thiokol joint never failed under design conditions, and that the RSRM joint with capture feature would not fail even at Challenger-like conditions, I think the decision has to go the other way.