: Well, obviously. But anyone figured up the energy expenditure yet?
: There's the easy math, in which the energy is simply the ship's mass times
: gravitational acceleration times height achieved and there's the hard
: math, in which you account for the fact that the gravitational
: acceleration is a function of the height and the ship has a final velocity
: that also requires energy to achieve.

That's what the equation I used figures, because you AREN'T just shooting it and letting it coast. It takes the fuel with it and has a constant burn. As you add fuel, the more mass your ship has because you have to lift the fuel too, so the more fuel you need. You start to need massive amounts of fuel very quickly.