[ExI] Getting into space cheaply

[Keith Henson]

I think I have a conceptual method to reduce the cost of going into
space well below the $100/kg level.

It involves using beamed energy heated hydrogen that is combined with
ram air as long as there is air to scoop up.  The average eqivalent
exhaust velocity all the way to LEO is around 20 km/s, even better
than Skylon at 10.5 km/s to when it runs out of air.

If you are interested in a short writeup and the spreadsheet, let me know.

Keith