Jumping the Gun.

From: Axel Walthelm [mailto:Axel.Walthelm@...]

> Mike, if I remember right, you voiced some doubt about mass-driver
> achieving delta-vs of more than 2 km/s
> due to some inherent delay in switching on/off the magnetic coils?
> In that case mass drivers would have only half the
> specific impulse of
> chemical rockets.

I was actually only reporting on the pessimism of others. I actually
thought that the pessimism was a bit misguided. Myself, I still have
tremendous optimism about mass-drivers. But like everything else ever
thought up, well have to build one full-scale to know that it will work
full-scale.

The O'Neill calculation would have assumed exhaust velocities comparable
to that of the lunar catapult (though I've heard it said that exhaust
velocity is not the end-all/be-all of performance for this application).

Regards,

Mike Combs