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CEV / CLV construction

Posted by: Andy Hill - Sat May 06, 2006 10:48 pm
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CEV / CLV construction 
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Post    Posted on: Wed May 31, 2006 3:26 pm
What is wrong with building on past experience (i.e. the J2)? The J2 has been advanced in the past. It was modified into the Linear Aerospike engine for X-33.

I agree we should have another engine that could do the same job cheaper by now, but we haven't got that. There is one windfall, in that the CaLV will at least now be using RS-68's, which will be a major improvement in cost (and thrust) from the SSME's.

I'll put it this way: the Polynesians managed to settle a huge amount of territory with canoes called proas. Proas were invented by stone age people who didn't have access to metal, writing, or wind tunnels, but they were still, until the early 20th century, the fastest sailing vessles ever built. At some point they met the needs of the islanders and development probably levelled off.

So if J2 derivatives are our proas for the time being, fine. The more we build, the more we will understand them and the cheaper they will be. It would be nice to go to the moon with a nuclear-thermal stage or get slingshot there by elevator, but that isn't going to happen yet. CaLV will give us heavy lift so we can at least start to imaging the possibility of actually getting some of the things that will generate a need for better development later.

I like Rutan. I like that he's an alternative voice, but for political reasons he's not going to get us to the moon, and he's not going to get us heavy lift.


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Post    Posted on: Thu Jun 01, 2006 7:59 am
Rutan's Scaled Composites is part of t/Space - who are selcted as one of the six COTS-finalists.

So govermental reasons may result in Rutan together with others developing an orbital vehicle. It will not be that a problem to develop next a lunar vehicle - which can be financed by the revenues got for the COTS if t/Space wins the COTS-finals.

This also may mean that HLLV isn't required - the Lunar Siyuz-thread together with at least one other thread in the Financial Barriers section is posinting to that direction abit.

Also there is a NASA-document which includes lunar COTS - I will look for that document.

At this point an explicit remark I feel to be required - the HLLV-discussion looks a bit one-dimensional and single-directed to me since all alternatives are ignored and no thoughts are invested into alternatives, no development ideas. As if something off-topic is behind it - I agree that these words include expression of dissatisfaction about what's going on and about neglecting chances to reduce costs and keep costs as low as possible.



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Post    Posted on: Fri Jun 09, 2006 7:40 pm
Actually all alternatives except HLLV have been explored. We have seen all sorts of Rube Goldberg contraptions offered with people all but falling all over each other in trying to find a reason to keep from building big rockets--when we know how to build that now--with SE and beamed energy a long way off.

HLLV saves assembly, number of engines expended, upper stages--and gives us greater reliability in engine-out performance. You can't beat it.


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Post    Posted on: Sun Jul 23, 2006 6:16 pm
NASA is now reducing the size and weight of the CEV service module.

http://www.nasaspaceflight.com/content/?cid=4659

It would seem to me the 50% reduction in size quoted either means that it was ridiculously over specified or they have removed the steroids from Apollo. Perhaps it failed a dope test, wonder who the dope was?

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Post    Posted on: Thu Jul 27, 2006 6:26 pm
It appears that NASA is considering more changes to the CLV now, instead of the bg stick they are thinking about using twin 3 segment SRBs with a liquid core using 2 J-2X engines.

http://www.nasaspaceflight.com/content/?cid=4670

The plan has a number of things going for it but I just wish they would make up their mind about what they are doing, its been over 2 years since Bush started the ball rolling and they are still discussing options. I am beginning to believe that this will be yet another fiasco but this time the US wont have the shuttle to fall back on. :(

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Post    Posted on: Fri Aug 04, 2006 5:35 pm
I don't know how serious the rumblings are. At least it keeps Michold busy and it is a way of getting engine-equiped tank production accelerated.


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Post    Posted on: Sun Aug 13, 2006 9:24 am
There seems to be a lot of anti-stick feeling around, an example of which is this article from Jeff Bell (although it must be said that I wonder sometimes whether he over does it a bit on the NASA bashing front).

http://www.spacedaily.com/reports/Scrap ... k_Now.html

I'm not quite sure what to think about using a Delta IV or Atlas V to launch CEV, I have a feeling that Boeing or Lockheed would screw the same money out of NASA for converting either for CEV use that a new CLV would cost so it is probably better to stick with a shuttle derived option.

The more I think of it the twin booster CLV concept looks a better bet, its closer to the STS configuration so the flight issues should be a lot less complicated to work out than a new single booster design. Also using 3 segment SRBs should mean that it might be possible to increase the payload by adding an additional segment, it is unlikely that this could be done with the already stretched 5 segment CLV.

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Post    Posted on: Sun Aug 13, 2006 3:32 pm
Hello, Andy Hill,

regardless of what I think about what Bell says his finishing thoughts are reiminding me to one of gaetanomarano's thoughts. ...



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Post    Posted on: Sun Nov 12, 2006 10:25 am
Yet more problems for the CLV, according to this article in SpaceRef it is underpowered:

http://www.spaceref.com/news/viewnews.html?id=1171

The article says:

Quote:
the current design is underpowered to the tune of a metric ton or more. As currently designed, Ares 1 would not be able to put the present Orion spacecraft design (Crew Exploration Vehicle) into the orbit NASA desires.


It is not clear whether Ares requires an additional ton of thrust or the payload is a ton to much for it (I would guess the payload is to heavy).

The suggestion of using a couple of side mount solid rocket motors IMO is stupid, NASA should be designing a launch vehicle with as big a payload margin as possible so that it can accommodate any increase in capsule weight. Reducing Orion's weight will result in a less capable and inflexible craft.

Using the stumpy 3 segment design from a few weeks back would be a much better solution IMO.

http://www.nasaspaceflight.com/content/?cid=4670

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Post    Posted on: Sun Nov 12, 2006 11:38 pm
All new vehicles encounter problems during their initial design fase. That's why there is an initial design fase in the first place. If the engineers designing new launch vehicles did not expect any complications with the new designs, then the shuttle would have been replaced by a better craft ten years ago. I doubt an alternative craft to the Ares I will ever be built, mainly because it would be far easier to fix the current design problems with Ares I than to start building a completely new and more expensive design. While I don't expect NASA to complete the Ares I on time, they have the best minds in the nation working on it and I would be very surprised if the Ares I did not fly.


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Post    Posted on: Mon Nov 13, 2006 7:09 am
The (expletive-deleted) Shuttle should have been scrapped in the design stage. Pushing a poor design too far is the cause of the massive time & cost overruns of the STS program, and ridiculous cost per mission. Not to mention the 14 deaths. Accidents have to be expected in such a difficult endeavour, but those 2 accidents were survivable with proper design.

Less than 1% of the Constellation budget has been spent on the CLV so far. Dropping the air start SSME for a J2-X has made the design impractical without excessive compromise. Now is the time to stop and start again. Anything else risks falling into the Shuttle trap:

"When failure is not an option, success gets very expensive"

Stumpy sounds like a good idea at first glance, although DIRECT may be less expensive, but would require more changes to the lunar architecture.


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Post    Posted on: Mon Nov 13, 2006 9:48 am
Fighting Falcon wrote:
All new vehicles encounter problems during their initial design fase. That's why there is an initial design fase in the first place.


True, which is why NASA should have started with a bigger payload margin in the first place. Historically nearly every vehicle has weight problems during construction, why make it more difficult by not allowing for some extra payload capability?

Having an initial design phase should also root out the designs that are impractical and bare in mind that the first concept is not always the one to go with. As NASA thinks more about the design it should be willing to recognise if there is a better alternative that would give more flexibilty.

To keep downsizing the capsule to accomodate a less powerful launcher results in the question why not just use an EELV insead on a smaller capsule still?

Having a more powerful launcher results in solving a lot of the technical problems associated with reducing weight and allows a certain amount of payload flexibilty, for instance Orion will be able to fly less stressful flight paths without reducing its capability (the shuttle does this but it reduces the cargo it can carry).

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Post    Posted on: Mon Nov 13, 2006 4:16 pm
As the engineers say, "it always takes longer and costs more". Longer that what? Longer than planned, desired, forecast, what you think it should. Costs more than what? More than you want, have, expect, plan for. So just longer and more. NASA does that a lot.


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Post    Posted on: Tue Nov 14, 2006 1:57 am
Yep and that's with the 'best minds in the country' apparently :lol:

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Post    Posted on: Fri Dec 22, 2006 10:29 pm
www.directlauncher.com to the rescue.


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