Ian wrote: I can't see the point in jets, really... Small jet
sustainers might be fun, though.

Fun is the key word. Since we are wishing into the future, my thought
is that the small jet engine should be more reliable due to fewer
moving parts (likely just one). The weight should be less, the size
smaller, and operation should be smooth with little to no vibration.
Extension and retraction is quicker. Their drag profile is much
smaller; thus creating less of a problem if it extends but fails to
start. For repairs, it can be removed easily and put into a shoe box
to be mailed. All of these characteristics make for a great jet
sustainer, and hopefully an even better self-launcher.

I'm not an engineer, just a dreamer. But designers should be able to
come up with something small, powerful, reliable, simple, and of
course, inexpensive (sort of).

Raul Boerner