Colonel_Korg wrote:The task as I see it is how to get 1.5MV DC electric power to provide lift in a flight envelope that goes from 0 fps at sea level, to 25,000 fps in a vacuum and everything in between.
What has been kicked around here for a while is VTOL-capable electric fans to ~M1, electric turbines to M2-3 with indefinite cruise, and QED-ARC (relativistic electron beam) from there to orbit (propellant injected for this mode). This avoids the REB's ozone production at low altitude. A vehicle mass issue (beyond radiation shielding) is the HVDC down-converter mass (needed if you want to use some evolution of modern, high-power-density, low-voltage, brushless motors, probably involving magnetic bearings and superconductors). MV-level "electrostatic" motors would avoid the down-conversion mass, but are also an entirely new R&D project (the REB likes high voltage).
Colonel_Korg wrote:Since we don't know how to make an inertia-less drive (i.e. no reaction mass) then we are going to need some kind of reaction mass to propel our craft.
Plan A is Mach Effect. Plan B above is a backup, until MLT research yields sufficient thrust.
Colonel_Korg wrote:So you have to switch to a method that can heat the air in a supersonic air stream, i.e. a scram-arc-jet. Once you are out of the atmosphere, (i.e. above 100,000 ft) then you have to use reaction mass you have carried along with you.
QED-ARC using a REB above ~100K ft, maybe lower.
Colonel_Korg wrote:How are you going to keep the skin of the craft cool?
Cruise slower than an SR-71. Use REB(s) as an "aerospike" ahead of the vehicle. Possibly more options, like aspirated metallic TPS or magnetocaloric cooling. Use air-only as propellant for this mode, to avoid expending cryogenics or onboard propellant, allowing indefinite cruise pre/post-orbit (only small amounts of H, B11 consumed).
Colonel_Korg wrote:These are all the problems we are facing trying to build a SSTO craft. Yes Polywell may give of lots of power, but having adequate power is only an answer to a small part of the problem of getting to orbit.
Agreed. It's a fun problem though.
GIThruster wrote:Now that Constellation is cancelled, I'd like to know where NASA intends to spend its money.
On improving relations with the Muslim world:
Former NASA Director Says Muslim Outreach Push 'Deeply Flawed'
KitemanSA wrote:On the other hand, the SSTO accelerates as rapidly thru the atmosphere as possible.
If it's chemically fueled, it has to. It will run out of fuel quickly. There are definite operational (economic) advantages to a Polywell SSTO capable of long-duration atmospheric cruise both before boost and after reentry.