belbear wrote: Direct fusion powered flight may indeed need some radical fuselage design, totally departing from the classic tube-with-wings model.
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With sufficient clearance between reactor and occupants, less neutron shielding is necessary.
Shielding may only be required toward the passenger and crew, not away from them since a lot of free air is also an excellent shielding.
seems to me, that these constraints lend themselves to longer tubes, with reactor and engines in the rear, except possibly in lenticular aircraft, where the pilot might be separated from everything else by a hemispherical shell of shielding.
