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9:20 am
December 5, 2009
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Luke Maurits
| | Adelaide, Australia | |
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I found an excellent broad article on spacecraft structure at answers.com today, of all places. Well worth reading.
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Main CLLARE workgroups: Mission Planning, Navigation and Guidance. I do maths, physics, C, Python and Java.
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1:24 am
April 23, 2010
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KellyJ
| | Australia | |
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Luke,
Had a browse of the CLLARE overview document, and read with interest that the current proposal for the command module is to have a discardable outer shell and heat shield with the structure to be made out of titanium! I find it slightly difficult to understand why a low cost project has chosen an expensive, hard to work material and then chosen to make the external structure disposable while keeping the aluminium internal structure. Is there any reason for this compared to a standard aircraft type aluminium structure?
Titanium is a great material, but like carbon fibre there are significant downsides to it. It has applications for some specific high strength parts, especially for military applications but for a project like this I would question its use. I posted another thread on the DH-1 from the book "The Rocket Company" which has some basic calculations for things like heat shields and shows that it is entirely feasible to make a reusable vehicle using standard aluminium structures and reusable heat shields. I will dig up the numbers to post here to show how they did their calculations.
There is a lot of information on designing aerospace structures using the standard alloys, but not much that I know of for making structures from titanium.
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6:37 am
April 23, 2010
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Luke Maurits
| | Adelaide, Australia | |
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| posts 1229 |
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Hi KellyJ,
Thanks for your comments. I would be extremely interetsed to see the details and numbers for the aluminium structure and reusable heat shield proposal that you read about. To be honest, everything in the Overview Document from a structures material is based entirely on hand waving because we haven't really had anybody with a decent materials background come along to advise us otherwise. It is probably a quite sub-optimal solution and I have no objections to reveiwing it if needed.
It should certainly be our ideal to stick to cheap, readily available and easy-to-work with materials wherever possible. Mass concerns are probably going to prevent us from using steel too much, but it certainly strikes me as feasible that we could get away with doing most things using aluminium.
Do you have much background in materials and structural engineering? This sort of skillset could be a real help to us. I'd partiularly like to talk to somebody about the relative ease of fabricating different shapes (spheres, cones, Soyuz "headlamp" shapes) out of various materials.
By the way, the proposal in the CLLARE Overview Document is no longer "alone". We've decided that to help increase our chances of an optimal design we're going to spend some time fleshing out multiple "competing" proposals for CLLARE before going into too much detail. I personally no longer favour the proposal in the Overview Document (with the separate CM and lander), and instead am very keen on a single-vehicle proposal outlined in this thread, which I'd love to hear your thoughts on.
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Main CLLARE workgroups: Mission Planning, Navigation and Guidance. I do maths, physics, C, Python and Java.
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1:16 am
May 6, 2010
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KellyJ
| | Australia | |
| Member | posts 13 |
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Luke,
I have put a very good AIAA research paper titled "Structural Configuration Analysis of Crew Exploration Vehicle Concepts" [AIAA 2008-2082] onto the recommended reading page. This has some very good information about stress analysis and structural details for a CM type of module. Well worth a read to see how to make a light, strong CM structure from aerospace aluminium alloys.
Kelly
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1:28 am
May 6, 2010
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Luke Maurits
| | Adelaide, Australia | |
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| posts 1229 |
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Excellent! Thanks very much for this, I will read it with interest.
I am currently working on a very thorough report on how much mass we can land on the moon given a Falcon 9 launch vehicle and LOX/LH2 propulsion for TLI/LOI/TEI. Once I am done with this, finding a good ball park estimate of the structural mass of our CM will be vital to assessing the feasibility of the various possible flight architectures.
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Main CLLARE workgroups: Mission Planning, Navigation and Guidance. I do maths, physics, C, Python and Java.
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