Nydoc wrote: Would this be feasible to do with just the electric turbines and without the VTOL electric lift fans so as to decrease the weight of the vehicle and increase payload mass?
It would, but far
more power is required to get to orbit from the M2.5 regime, so why not include VTOL in my "dream" vehicle (remember, it has to land and take off from my back yard). The fuel mass penalty for a Polywell (small
amounts of hydrogen and Boron 11) is negligible, unlike chemical propulsion (e.g., Shuttle fuel/oxidizer tank). No big mass penalty for letting the reactor run all day (as when cruising in the atmosphere before/after orbit).
Assuming efficient, hubless, rim-drive electric motors such as NASA studied, lightweight composite and/or metallic glass fan blades and maybe room-temp superconductors, the VTOL penalty may be more severe in volume than in mass.
All-electric propulsion allows for some interesting possibilities, such as multiple motor-fan modules in rotatable, spherical housings (similar to a ball valve) which can be either aligned along a propulsion duct or turned orthogonal to the duct for VTOL. CFD experts are needed to find blade designs useful from VTOL to M2.5 (REB initiation speed per Bussard). Nice thing about the "ball valve" arrangement is that the VTOL inlets/outlets are sealed for higher speeds simply by rotating the motor-fan modules into alignment with the main duct.
The big question with regard to using Polywell as a subsonic
flight power source is how do you convert >1MV to a lower voltage without a huge mass penalty. Low-voltage motors have advanced far, and are probably the best choice for slower speeds IF the low voltage is available. The REB is happy with high voltage.
Also, would it be possible to power the REB using SAFE-400
SAFE-400 produces about 0.1 MW or 0.0001 GW. Reaching orbit with a REB requires power in the multi-GW range. 93143 once posted a model that assumed ~6 GW Polywell output. He assumed a high mass penalty due to radiation shielding (gammas being the worst). Things improve with lower gamma emission. We need some real Polywell data to know what the gamma situation will actually be.