I'm interested in the economic and operational aspects of launching big payloads with multiple Skylon missions. Surely cost/ kg maintains in units of 15,000 kg? How feasible would it be to construct, say a 10 tonne comsat in two or more parts and mate them in LEO, and propel said comsat to its desired orbit? Would the Skylon launch missions have to be close to each other?
Quote from: Turbomotive on 12/13/2012 07:18 amI'm interested in the economic and operational aspects of launching big payloads with multiple Skylon missions. Surely cost/ kg maintains in units of 15,000 kg? How feasible would it be to construct, say a 10 tonne comsat in two or more parts and mate them in LEO, and propel said comsat to its desired orbit? Would the Skylon launch missions have to be close to each other?Would dual almost-simultaneous launches be more feasible with two Skylons than with two conventional launchers?While two planes would need to duplicate all the ground support equipment, could the second use the runway once the first is clear and no abort is required (ie minutes apart)?It also seems to me that the airplane-mode phase of the launch might offer a more "relaxed" environment for two Skylons to align themselves in preparation for LEO rendezvous.cheers, Martin
The total mass at departure from Earth is 1357 tonnes. Of this, 1083 tonnes is propellant. The ship is assembled in Earth orbit, and a total mass of 1541 tonnes must be placed in orbit for the first mission, including construction platforms which can be re-used for subsequent missions. A total of 25 main assembly launches planned for each Mars mission. Two or three more are required to deliver the crew and top up the propellant tanks. At a rate of one launch every two months, the construction phase is expected to take 4.6 years.
Off-hand I'd say this is pretty much the way Skylon would have to work within an overall "system" of transportation. If the required payload won't fit into a single Skylon launch then the "idea" is that satellite makers would find it more 'economical' to change the way satellites are made to fit into the available payload margins. This is based on the assumption that Skylon will be cheaper and more reliable to operate than any other LV and therefor will pretty much dominate the market.
Thanks - it's my understanding of comsat trends that while coverage will extend to most sparseley populated areas (where a satellite is more cost effective than cables), there will be certain in-demand footprints for which satellites will probably continue to become ever bigger. From all your replies, I read that Skylon will be continue to be economic for large payloads split into pieces.
IMHO, the majority of the "major" aerospace companies seem to be focused more on tech-development rather than actual capability. This is probably makes a "sense" given the general lack of interest, (and money) in high speed and hypersonic aircraft in general. I consider practical scramjet applications, (note I said "practical" that's an important point ) a "future" technology due to the difficulty in USING a scramjet for any "practical" purpose beyond weapons technology at this point.
Yeah, that's the real point. The aerospace majors aren't going to spend money to develop combined-cycle engines (like SABRE) unless a government give them money to do so. Until or unless a major government wants a hypersonic airplane, they won't bother.REL was founded precisely to avoid all this. They are personally accepting the technical risk and are developing the engine themselves. If it fails, no government or corporation gets burned. If they succeed, then the barrier to entry for hypersonics and SSTOs is drastically lower than now.
Let's see - Thatcher funded them in 1985, only to stop without a warning in 1988- the government (more exactly, the British military) classified RB-545, forcing REL to start again from zero - when battling for ESA funding, they faced the French (Hermes, Ariane 5) and German (Sanger) governments. It was certainly not pretty nor a happy experience. I think all three historical elements explain why REL doesn't wanted / want government funding for Skylon research and development. They took the whole issue by the other end: build something interesting and groundbreakring (see, the heat exchanger tests) then (and only then) have a government interested enough that it may fund it further.
Everything gone quiet - problem finding money?
Christmas-New Year holiday!
REL should use a biplane design for LAPCAT, would eliminate the sonic boom.http://news.discovery.com/tech/biplane-could-go-supersonic-120320.htm
Quote from: guckyfan on 01/14/2013 04:47 pmREL should use a biplane design for LAPCAT, would eliminate the sonic boom.http://news.discovery.com/tech/biplane-could-go-supersonic-120320.htmGreat idea. Add another level of complexity to an already enormously complex project.QuoteWithout sonic boom a mach 5+ airliner has huge potential which alone could easily legitimize 10bn+ dev. cost.
Without sonic boom a mach 5+ airliner has huge potential which alone could easily legitimize 10bn+ dev. cost.
Also it seems JAXA has a precooled engine program and an experimental vehicle is in development.http://arc.aiaa.org/doi/abs/10.2514/6.2012-5839If JAXA is serious about this we can expect ESA to be interested to fund further research in that field.