I have always thought that all that energy to launch one of those things straight up could be avoided if it were to take off at an angle and slowly exit earths atmosphere. But then again if it were so then it would have been done, So what do I know.
David - here's the rocket science...
There's a thing called
gravity drag which relates to the efficiency of rockets operating in a gravitational field. You can see that a rocket which only generates 1.01G of thrust is going to be very inefficient in a 1G field...it'll take a long time to get anywhere. That "long time" equals burnt fuel, big tanks, more mass. The shuttle generates around 3G with its boosters lit, and it goes straight up, at first, in order to minimise the time spent under gravity drag, as well as reduce the time spent in the thicker air of the lower atmosphere.
But of all the energy required to enter a low Earth orbit, 94% is spent accelerating to the right speed, and only 6% is spent on getting up to the right altitude. (This is why Richard Branson is offering suborbital high flights - it's far easier to achieve than orbit.) Clearly most of the shuttle's eight-minutes-to-orbit is spent accelerating to orbital speed, around Mach-24. The drag resulting from this sort of speed is huge in the lower atmosphere, so most of this acceleration takes place in the near vacuum above 50km (after the boosters have dropped off).
Flying gently into orbit, as you propose, will be a valid (and more saner) choice once engine developers crack what are known as
scramjets - air-breathing engines that can operate from around Mach-3 to Mach~20ish. Once that's done, a lifting body would be able to fly to the edge of space, carrying just fuel and not - like current rockets - requiring an oxidiser tank as well. They'll still need a small rocket to work in the vacuum of space, but the risks of "flight" over "brute force", such as we see in the shuttle, will be reduced.
Regards,
Andy