vansig wrote: or place the reactors in the tail section, then have just a single shield for the bunch
Misses the point. About half of the energy from FF derives from capture of the X-rays using the onion-skin. So the space issue is real, as each FF must have its own onion-skin. Twenty of those would easily fill a 747, leaving no room for payload.
Much easier to use FF as an energy source from which to create hydrocarbon fuel.
