Here is a challenge: Design a concept (BOTE) for an SSTO RLV. It must be capable of high flight rates (several times per day). Market is space tourism. An NTR is allowed, but air-launch is not.
Easy, just do it on the Moon. 4 RL-10 motors, single tanks for LO2 and H2, horzontal landing capability, with a total dry mass of about 10 tons.
I suspect that ELV can be done using an ACES variant (it has a high enough mass ratio). The question is then: Can it be made an RLV?
Quote from: tnphysics on 05/09/2010 12:20 amI suspect that ELV can be done using an ACES variant (it has a high enough mass ratio). The question is then: Can it be made an RLV?The billions spent on RLV studies and development over the last 50 years says: Not for a price anyone is willing to pay. There is a vast body of serious work on this subject, which a BOTE forum post is unlikely to improve on in any way. Hint, google "ssto" or "single stage to orbit".NTR isn't likely to help you, it's a lousy first stage even if you ignore environmental problems. Orion can do it no problem, but the EIR is going to be a doozy and the neighbors are going to complain.SSTO ELVs aren't a problem, if you are willing to accept very low payload fractions, the required mass rations have been within reach since the sixties. The question is whether it is worthwhile, and the answer to date appears to be a resounding no.
Are thrust-augmented nozzles allowed?
What about the GCNR proposal?
Superstrong, light and heat resistant graphene tanks and an SSME or a few, use a skirt for stability or tumbling to avoid re-entering engine first, fall into the ocean, recover by ship and wash the engines.Very expensive to design, build and use and tedious, workforce intensive, incapable of high flight rates, unreliable and dangerous as well.Average ISP perhaps 4200 m/s so a generous 11 km/s delta vee needs a mass ratio of 13. Low acceleration off the pad and very high acceleration in later parts of the flight.1 ton = 1000 kg:300 tons gross, 2xSSME, 23 tons dry, which is 6 tons engines, 1 ton other stuff, 15 tons tanks + skirt + intertank + thrust structure + fairing + payload mount, 1 ton payload. Liftoff T/W 1.2. End T/W 16 so that's an acceleration of 16 gees.
Quote from: tnphysics on 05/09/2010 03:07 amWhat about the GCNR proposal?Which GCNR proposal ? If you have a specific one in mind you think is credible for ground launch, why not post your own sketch ?If all you are saying is that some paper GCNR has a paper ISP of 3000, so what ? I have it on good authority that fairy dust has an theoretical ISP of eleventy gajillion.