re: You post made me remember something I thought about a few months ago
The US Navy is researching electromagnetic catapults for aircraft carriers. It's a old idea - a prototype system was built and tested in the 1940s. I've heard they're researching electromagnetic arrestor gear. One idea is to take the energy captured during a carrier landing by one plane could be used to help accelerate a plane being launched by the catapaults.
I've heard Burt Rutan speak of similar technology for ordinary aircraft.
