🚀 go-pugleaf

In article <Added.sYBzIGy00UkT8Q409X@andrew.cmu.edu> SCOTT@GACVAX1.BITNET (Scott Hess) writes:
>... One device I've read about in Jerry Pournelle's
>"High Justice" used lasers. It seems that a powerful ground-based laser
>is fired into a cavity at the bottom of the spacecraft. It is pulsed on
>and off, at a high speed. The cavity is vented in such a way that it draws
>in air. The laser heats the air very quickly, so the air pushes out the
>bottom, propelling the craft. Then more air is brought in ... Basically
>a ramjet with half the engine ground-based...
>My basic question is this: Does this work? ...

In principle it ought to, although arranging for the laser to heat the
centimeters of air in the cavity but *not* the kilometers of air in the
rest of the beam path is a bit tricky.

The US has a small research program on laser launchers, although they're
currently focusing on rockets rather than air-breathing systems.  It is
hoped that SDI will develop the necessary lasers and optics.  It looks
both feasible and promising.  In particular, with short-pulse lasers,
it scales down well.  Launching capsules weighing tons takes formidable
power sources and lasers, but if you're willing to settle for something
smaller, the system (and its budget) gets much more manageable.
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