RyanCrierie said:
mz said:
What Ares I? It is not even flying. How can they predict its safety so accurately? MSFC has not designed rockets in decades.
It's a significant boost in reliability and safety over the current stacked side by side configuration found on Shuttle -- and all the other alternatives, such as Delta IV Heavy -- have side by side configuration -- which means a single failure in a strapon booster (whether liquid or solid) sets off the bomb next to it.
Unfounded assumption again. A liquid rocket engine can often be shut down in case there is a problem. And also, it often fails much more gracefully than a solid anyway.
And who says one has to use heavy versions for crew anyway?
Secondly, it's a TSTO rocket; there's no third stage. This makes the rocket more weight critical, but since a third staging operation is eliminated, reliability goes up.
Oh, by the way Delta IV heavy versions without an upper stage were studied too. Soyuz has lots of stages and engines and seems to operate very well. It's bordering on NASA FUD.
There are questions like the high q because the solid rocket accelerates fast, meaning a huge launch escape tower and high gees.
Left unsaid is that because of high acceleration, the rocket can launch in higher winds more safely, because it clears the tower faster, rather than slowly nosing about for the proper attitude like the Saturn V did for the first couple seconds.
And five to six gees isn't brutal when you're sitting in a couch, and only have to endure it for a couple minutes before the first stage burns out.
I meant the gees mainly in case of an abort. Also, other stuff plays into the high wind launchability. How tall is Ares I? How large is the huge hydrogen tank at the top, because of the lousy impulse of the first stage? How does the STS heritage thrust vectoring work off the pad?
And the solid rocket can not be shut down.
We do it all the time with ICBMs; which require extraordinarily precise stage shutdowns to meet their accuracy goals.
How you shut down a solid rocket is pretty easy -- you have blowout vents on the top of the solid rocket motor; when you want to shut down the motor, you open the vents; and the pressure inside the rocket motor drops to a level too low to sustain combustion, and the engine falls silent.
I don't think it was planned for Ares I, IIRC since it's very dangerous on a crewed rocket, same as why it was not planned for STS.
What about the thrust oscillations?
You mean the oscillations which failed to be a major issue with Ares I-X; which was a properly mass distributed boilerplate?
Ares I-X was pretty much a shuttle SRB though that has flown for a long time and doesn't have that much in common with the proposed Ares I solid stage. It also didn't have flight weight structures meaning the structural resonance frequency was probably different. Even the flight software was not related to Ares I.
Being able to put up 160 tonne modules in LEO is faster and more efficient than slowly assembling 20 tonne modules -- look at the comparative sizes of Skylab versus ISS.
Nah, one can't deduce that from that. Saturn V isn't around anymore for some pretty good reasons - it cost a huge amount of money and it would have been used only rarely with the available money.
Just building a new heavy lifter and wishing it won't happen again is not a good plan. Instead one has to plan for the available money and enable improvements in the architecture.
And when would Ares V have flown?
In about 2014-2015.
The plan was to do it sequential -- develop the Orion Spacecraft and Ares I for immediate LEO needs; and then once those two have gone into production and are deployed; the money shifts to the Ares V project office. NASA can't develop everything at once anymore. The money isn't there anymore, unlike Apollo.
And it doesn't even have money to develop stuff sequentially. Once it starts operating something like a NASA dedicated space launcher, that sucks most of the money. All the plans were very overoptimistic. One can spew out dates and capabilities but it doesn't mean anything.
And with what synergies with STS or Ares I? Everything was different. SRB segment number
The SRBs on Ares V would have been 5 segment, like Ares I.
Nope, 5.5 segments on Ares V.
For example, if you choose rockets that are already flying, you can actually do something and keep operating the ISS, perhaps even go to asteroids etc because you need to spend less money on development.
Actually no. You need to man-rate them first. And that's very $$$$$$$$.
Man-rating is a vague concept that NASA can use to claim anything it wants.
For example EELV:s were considered OK for OSP (Orbital Space Plane that preceded ESAS).
The "Black zones" of EELV:s were also a myth.
It's all been documented except by the trade press, hence most people here don't know about it.
Ask professionals who have worked with EELV:s.
Better to leave cargo lifting to cheap expendable rockets that you don't care about if they explode and leave people hauling to rockets that are designed from the start to maximize crew safety and reliability.
Soyuz is pretty reliable by track record, it has quite many engines next to each other etc..
I think nowadays few rockets are designed as not caring about mission failure - they are extremely expensive to businesses and often bad to national security.
The EELV:s were developed with moderate budgets and to a moderate schedule and have flown with a good safety track record. One early engine shutdown inflight so far?
And do what meanwhile? Stop all advanced programs since Ares I sucks so much more money? Stop putting humans to space? Deorbit ISS?
This isn't the Gap between Apollo/Skylab and Shuttle; since we can hire the Russians to send cargo and crew up to the ISS, so mothballing it for a couple years makes sense; until we can deploy a large re-entry capsule which can hold six people -- that's the limiting factor on how much we can use ISS -- the rescue vehicles.
Crews were limited to just three people because of the limitations of docked Soyuz; and it costs roughly the same amount of money to run three-man ISS as it does six-man ISS.
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Or if you have both a Soyuz and say an american small capsule Z there, that both can hold 3 people, you could keep 6 people on ISS.
The rockets have been there since 2002 and more are coming. But since 2004 or so, it's been anathema inside NASA to say a small perhaps commercial capsule could fly to the ISS on an EELV.
Since everything else takes billions upon billions to develop AND to operate and is bordering on fantasy and is certainly very counterproductive.
The ESAS study which chose the 1.5 launch Ares I / V configuration was a sham on EELV:s, getting so much of data wrong that the analysis is worthless in that regard.
Point out to me any rocket family present or planned which can offer 160 tonne to orbit capability without endless strapons or clustering. That's right, you can't.
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That was not my point, as anyone can read above. What is clear is that you're not arguing against ESAS' huge flaws. And it is also a false assumption anyway to say you have to launch everything at once. Most of the mass is liquid oxygen.
ESAS again assumed that only one launch pad could be used (uncovering unfounded assumptions happens often if examining space policy with any semblance of rationality, this case was noted by Jon Goff) and hence launch delays would kill any multi-launch scenario. One would tend to think that with so many billions at stake, someone in the team could perhaps have had some imagination?
Really, the most realistic explanation I've seen is that Ares I and V are Mike Griffin's babies from the earlier Planetary Society study. Maybe he thought keeping all those STS 2people in the same jobs would be the most important thing.
AFAIK, Ares I was not very far because of problems like underperformance and thrust oscillation, but I'm not an expert on this. I also don't know how many billions was spent there.
You mean like how thrust oscillation was a complete non-issue in the Ares I-X flight?
Anyway, it really does not matter if Ares I underperforms; because all we need it to do is reliably and safely deliver the CSM stack into orbit. The heavy stuff can go on the non-man-rated Ares V.
Why then go even as heavy as Ares I?
25 tonnes for putting four people in LEO is total overkill. Soyuz is perhaps 8 tonnes.
It doesn't make any sense any way you look at it, except from jobs protection point of view.
I also love the claims about how unsafe segmented solids are -- someone claimed this on NASA Watch:
"Crane operations for stacking are tedious, hazardous, and expensive. If a segment is dropped in the VAB the entire structure is likely to burn down before anyone can escape."
Because you know, we've never invented insensitive solid rocket propellant at all? If you dropped a SRB segment, it would probably dent the casing, and make a ungodly mess on the floor from all the propellant bits, but it wouldn't catch fire spontaneously.
Ares-IX had very little to do with Ares-I except perhaps the shape. I guess it validated some TVC and Aero issues.
For solids, the facilities required are extensive. One Shuttle SRB weighs more than the whole unfueled Saturn V stack. I'm not sure about how it ignites. There was a fireworks display at the propellant factory during the Challenger stand down.