"The military is the only organization which really has experience with aerial refueling..."
Also look at figure 2 here http://www.ai.mit.edu/projects/im/ma.../spacast3.html
A quote from the article: "Space operations must become as routine and non-exotic as air operations." Folks are looking at hydrogen peroxide and jet fuel in that neither is a cryogenic.
In what I've read in articles over the years--the general desire is for kerosene spaceplanes.
Some talk on Skylon:
"The phase of the hydrogen in the pipes changes from gas, a saturated vapor (two-phase), to liquid, making it quite difficult to control LH2 mass to feed the engine due to dramatic density changes..."
The anti Liberty folks here should enjoy this:
Then too, there was the TAV--but that would have needed a pad:
I always thought it was to be top mount with only the spaceplane in a clamshell bay above ground. Now Antice brought up some good points. Korolov was still pro liquid ICBMs what with R-9 I think it was, saying that it could be fueled rather quickly. So if Skylon can cause folks to "warm" to LH2, that's perfectly fine.