Reply To: General thought on old coal mines.

[belbear]

The conventional approach for fusion-powered flight is to use a fusion-manufactured fuel like liquid H2, But apart from the CO2 issue and fuel cost, little would change.
So I like more the idea of a direct-fusion powered aircraft. That would revolutionize commercial flight as much as the transition from props to jets did.

Direct fusion powered flight may indeed need some radical fuselage design, totally departing from the classic tube-with-wings model.

Among the possibilities are:
A triple-hull design, with two side hulls for passengers and the center one for the power plant. Or the other way around. Or a double-hull.
A thick-wing design (a.k.a. “flying-wing”) a huge wing that houses all fusion technology inside, the reactors furthest from the passenger section.
A tandem-hull tandem-wing design (actually two planes in line, the rear one for the fusion plant)
A vertical double-hull (two separate hulls above each other)…

Some of these have been built before, but apart from some military experiments, never used commercially.

Biggest problem is the cost of development. Most current aircraft technology was developed for the military with extensive funding during the cold war and its aerospace race: Jet engines, lightweight alloys, radar, inertial and satellite navigation….

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.
A more lightweight and efficient material than tons of water may also be used.

The water can even be used for more than just shielding: Injecting some of it in a hot jet exhaust increases power the way an after-burner does. Handy for take-off, punching the sound barrier or emergency situations.
When freed from the burden of fuel consumption, supersonic commercial flight will again become a possibility. Cheap, this time.
Now a 747 does only one quarter-globe flight per day, often necessitating two crews on board. A Mach-3 plane could do 2 or 3 of those with one crew, multiplying revenue. And fly a half-globe in one convenient 5-hour trip. And why stop at Mach 3?

With direct fusion power, adding extra weight for shielding is not really a problem, since you can add more engine power, multiple engine configurations and lifting surface without needing to add more tons of fuel. As long as the current airports and runways can take it, it’s okay.

Scientifically this may all be safe and sane, but alas, we’re still living in the post-Chernobyl era. If the media blurt out that flying in nuclear planes will make your dick fall off, few passengers will board them. Even if you have a 1st class seating space for an economy ticket.