Catapult really paints the wrong picture... but if you say ballista and actually mean a maglev rail accelerator then I'm down

If these are passenger aircraft, that probably wouldn't fly

> If these are passenger aircraft, that probably wouldn't fly

Well, it doesn't need to have the same rate of acceleration as a carrier's, but honestly it just doesn't make sense in general.

Right -- you could use the full length of an existing runway to have a gentle acceleration , bt I'd argue this makes a lot more sense than some sort of drone delivered jettisoned/retrieved battery if your goal is to reduce on-board energy expended for takeoff. Much less complex and the wear parts would be fixed at the airport rather than on every single airplane.

> I'd argue this makes a lot more sense than some sort of drone delivered jettisoned/retrieved battery..

Oh absolutely, it compares favourably to one of the most asinine first-pass approaches to this problem I've ever seen, heheh.

The real solution is to find a way to produce good liquid fuel from a cheap and abundant source of overprovisioned baseline power (maybe make hydrogen† from your nuclear power in off-peak hours).

Batteries are mostly composed of matrix, so even if you could extract energy as efficiently from the non-matrix materials in the battery as you can from hydrocarbon combustion, you would still be lugging around all that matrix.

† Yes, I get that it's 3 times less energy dense than good hydrocarbons, but it's a start when compared to batteries.

Might make more sense that you suspect. An airport designed to land uphill and takeoff downhill actually makes huge a difference in operating costs for heavy aircraft. Takeoff and initial climb are huge fuel burners.