Louis asked:

"what if you use a combination of a maglauncher and an ordinary rocket engine? Just to give your space plane a head start. Would it make sense for suborbital launches?"

You ***always*** have a suborbital launch with a gun launcher and always need a rocket engine to circularize the orbit. Think about the physics of the problem. You give the vehicle one kick in the behind at zero altitude. It then flies up to 100 km. Is it going to just stay at that altitude?

No, that's apoapsis (orbital maximum altitude) of an elliptical orbit. The vehicle will touch 100 km. and then descend back down to zero altitude. The only way you can keep it at 100 km. altitude is to fire a circularizing rocket and raise the periapsis (orbital minimum altitude) up out of the atmosphere. The only way you can avoid including the rocket is to shoot the vehicle at the Moon or on an escape trajectory like Jules Verne did.

Gary