20 years ago the EMSL program was alive and well, started by a small splinter group of aerospace people. It was a ground based version of the space based KKV, an orbiting electric cannon. The objective was to shoot projectiles directly into LEO. As you may know, one pound in LEO, moving at 5 mps and 100 miles up, is worth all of 4 KWH of electrical energy vs $20,000/# on the shuttle.
The rail gun was one system that was considered but after 3-4 shots the rails have to be refurbished, thus making it an impractical EMSL(ElectroMagnetic Space Launch)concept. A far better concept was the quenched superconducting rings idea. Here you have the sabot/projectile at the base with a series of su-co rings pulling upward on it. Release and then precisely quench(turn off)each ring as it passes(with heating lasars). Accelerations in the 150,000g to 300,000g range, the basic “freight car” to space vs the shuttle’s delicate 3g “passenger car”.
In about 300 ft of length you get the required 5 mps injection velocity of the 10 kg projectile. Movie film chambers at the top to maintain internal vacuum, lithium pore nose in the projectile...this was all worked out 20 years ago but vested interests NASA killed it(competition from a better idea). EMSL could put 2 shuttle loads/day in LEO at a tiny fraction of what NASA charges YOU as an STS.
bump for later reading!
Surely the accelerations involved would limit the types of payloads that could be transported?
(I'm not asking to be smarmy, I just can't think of one.)