As I understand the physics, the whole process could be made FAR FAR FAR more efficient if the rocket was boosted to about 40000 feet with a subsonic airplane, a' la' X-15 and such. It's above 75% of the earth's atmosphere (dramatically reduced drag), is already going 600 mph in the correct direction, and is 8 miles closer to the ultimate goal 250 miles up). This might not sound like much of an advantage, but if you've ever worked out the mathematics of the Saturn V (or space shuttle, etc), the VAST majority of the fuel was used up in the first 20,000 feet, maybe even the first 5000 feet. It would be even better if the first stage could be an air-breathing supersonic ramjet, but that's not my field of expertise.

Orbital Sciences Corp in Virginia do exactly that, but with a B52 and a 60 foot long rocket. They launch relatively small payloads for relatively cheap and have done it successfully on many occasions. ------------------------------------------------------------------------- Steven Weller | "The Internet, of course, is more | than just a place to find pictures | of people having sex with dogs." stevenw@best.com | -- Time Magazine, 3 July 1995