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Smaller, Cheaper and Simpler Spacecraft

Posted by: Andy Hill - Thu Mar 17, 2005 9:59 am
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Smaller, Cheaper and Simpler Spacecraft 
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Post    Posted on: Mon Mar 21, 2005 8:02 am
NASA must have learnt a lot since Apollo so I suspect that the Apollo CM was over engineered. Add to that the improvements in materials and manufacturing techniques and it should be possible to reduce the weight of a craft by quite a margin.

With the cost to orbit of every Kg so expensive it seems stupid to make such a heavy craft. Besides a lighter craft allows the use of a bigger range of launch vehicles.

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Post    Posted on: Mon Mar 21, 2005 1:23 pm
For one thing, you have to keep in mind that NASA didn't have the first clue what they were getting themselves into at that point (people were still debating as to whether the astronauts would be able to walk on the Moon, or if they'd sink up to their armpits in Lunar dust), so they generally built flying tanks -- it's the old principle of "I don't really know what I'm going to need, so I'm just going to take everything I can possibly think of". Orbital rocketry was also fairly new, along with re-entry, so the structures were definitely overbuilt. Also remember that metallurgy and composites were not nearly as advanced as they are now, so we could probably build a similar structure with a third of the weight.

Can we find schematics for the Mercury, Gemini, and Apollo orbiters? That would help tremendously.

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Post    Posted on: Mon Mar 21, 2005 2:36 pm
spacecowboy wrote:
Can we find schematics for the Mercury, Gemini, and Apollo orbiters?

I googled up this with "gemini spacecraft schematic".
http://www.hq.nasa.gov/office/pao/Histo ... emini.html


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Post    Posted on: Tue Mar 22, 2005 3:59 am
Spacecowboy Wrote:
… and (I think) don't tend to be as cost-efficient as a SSTO orbiter.

Theory aside, we have a sample of 1 for a 1.5 stage STS orbiter which carries almost 35,000 pounds of payload (and 125,000 pounds of dead weight) into orbit for a bit less than a Billion Dollars (1/2 Billion with creative accounting). This set a new high in cost per pound payload (not a record for efficiency). Attempted clones of the STS proved equally uninviting and were abandoned. By a miracle of vaguely specified technology – to be demonstrated in the X33 – a theoretical SSTO was to have delivered the efficiencies promised for the STS. The actual SSTO, if work ever progressed beyond the “radio controlled model” named X33, in theory would finally achieve what the STS Shuttle was supposed to do, with far more demanding “advanced technology”. However a convincing test of those theories lies abandoned in an Edwards hanger, never to rise above the desert floor. Note that, contrary to a skillfully nurtured public misunderstanding, the X33 WAS NEVER PLANNED TO CLIMB HIGHER THEN RUTAN’S SSO DID IN PRACTICE. And it would never carry a human.

I welcome advances in orbital cost per pound, but that is only one of the factors producing my ticket cost. I can’t afford to pay to move the 125,000 pound empty STS even at Fed Ex cost per pound rates! Yet even today’s orbital payload prices look interesting, when multiplied by the weight of an MMU and a reentry shield. (A few hundred pounds).


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Post    Posted on: Tue Mar 22, 2005 1:35 pm
Here is the official NASA chronology of the Gemini project, with plenty of accompanying diagrams.

And here is a list of and links to a set of NASA documents, including the all-important Familiarization Manuals for all three projects.

And here is a whole slew of NASA documents.

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Post    Posted on: Tue Mar 22, 2005 3:37 pm
It is pretty clear from looking at the Gemini manual why it is so heavy. There is a separate pressure vessel inside the capsule. The outer frame is riddled with access covers, each of which would need stiffening frames and attachment hardware. The two hatches have a complex latching system that looks pretty heavy. The window assemblies look heavy. (For the LM, making the windows smaller was a major weight savings.) And it all had to be strong enough to withstand launch and reentry stresses.
In contrast, we are assuming a light weight vessel with a single wall being the outer skin and pressure vessel, one (smaller) hatch and maybe one small window. And there are lots of systems we have not considered at all, like a cabin pressure relief valve, cooling system, ejector seats, radar, and telemetry.
Since Gemini was originally supposed to land on land under a steerable parafoil, there was also landing gear and doors, although that may have been deleted on later versions.


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Post    Posted on: Tue Mar 22, 2005 4:06 pm
So it would seem there is no real reason why a craft should be as heavy as the CEV requirements and a craft half the weight could be launched. So the obvious question is why havent NASA reduced the weight to allow the CEV to be launched on a smaller booster?

I think that NASA should see how much it would cost to get T/Space to build a light weight basic CEV to operate using a Falcon V class launcher. They didn't want to make a bid on the full CEV because of paperwork but they might be interested in a much smaller project that doesn't have all the paper attached. With an average EELV launch costing maybe a couple of $100m then it would be worth spending this with T/Space to see what they come up with.

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Post    Posted on: Tue Mar 22, 2005 4:30 pm
Keep in mind the Apollo CM had an overengineered heatshield (For good reason, considering where it came from). I'd have to look at the information again, but ESA's ARD capsule was quite a bit lighter while keeping the same shape as the Apollo CM (Which has very well understood reentry properties).

IMHO, ESA made a huge mistake not following up on ARD. It was one of their more interesting programs, and the closest Europe has come to having their own manned space program. Malignant lack of will and all that, I guess.


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Post    Posted on: Wed Mar 23, 2005 11:48 pm
Got anymore information on ARD all I found on astronautix was one paragraph saying it was a 80% scale model of an Apollo Command Module that was launched on an Ariane EPS in 1998. Do you have anymore links I could look up.

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Post    Posted on: Thu Mar 24, 2005 1:33 pm
All about ARD.....

Page #1
Page #2
Page #3
Page #4
Page #5
And of course the Google Search Results of which I've skimmed the first page.

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Post    Posted on: Fri Mar 25, 2005 6:49 pm
The attached article suggests using the shuttles under remote control to assemble the ISS and use a safer more cost effective craft to ferry astronauts, havent heard this suggested before. It also suggests resurrecting the X-34 which I am not sure is such a good idea.

http://www.bloomberg.com/apps/news?pid= ... Q&refer=us

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Post    Posted on: Fri Mar 25, 2005 10:50 pm
What could X-34 prove that SS1 hasn't?


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Post    Posted on: Fri Mar 25, 2005 10:53 pm
Reading through that story I find no mention of X-34. Where is your source for this?


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Post    Posted on: Fri Mar 25, 2005 10:57 pm
The last thing I recall about X-34, period, was Sapce Dev's interest in modifying it into a 5 person vehicle, assuming it would have it's Fastrac replaced with a SpaceDev hybrid.


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Post    Posted on: Sat Mar 26, 2005 2:46 am
bad_astra wrote:
Reading through that story I find no mention of X-34. Where is your source for this?
X-34 must be a typo. Here is a quote from the linked report
http://www.bloomberg.com/apps/news?pid= ... Q&refer=us
"The report also calls on NASA to immediately restart the X- 38 program to build a vehicle that could rescue station astronauts in case of an emergency or to get Congressional approval to order new Soyuz spacecraft from Russia for rescue missions."


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