Why do space rockets not take off like planes (i.e. straight up vs sideways and up)?
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Going sideways is because planes have wings in order to fly. Wings need air moving over them to produce the lifting force for flight, and a runway is just a straight paved road for the plane to accelerate up to the minimum speed (plus safety margin) needed for the wings to produce enough lift.
But there’s no air in space, so the wings would be useless weight once you’re out of the atmosphere. In general, the higher up you go, the less effective wings become since the air becomes thinner. Regular planes compensate by going faster – 500+ miles an hour is downright normal at 35,000 feet. But a spaceship is aiming for more like 500,000+ feet.
And of course, there’s drag. Wings do produce drag in the air. More than you might think, but totally worth it for ordinary flying. But that’s going to be a problem because…
Orbit requires you be going *fast*… like, a full orbit of the earth takes under 2 hours. That’s how fast you have to be going. That’s how much acceleration you’re going to need to do to get into orbit. Otherwise gravity will just pull you back down again. And that much fuel needs to be brought to perform that acceleration. That’s many many times the speed of sound, so you definitely don’t want to be going that kind of speed in the air. (higher orbits require slower speeds to maintain, but that climb is just more rocket vs gravity)
All things considered, rockets prefer their current method: straight-ish up to get out of of the atmosphere about as fast as possible, then accelerate into orbit once there’s no air to drag you down. A horizontal launch isn’t going to help make up for anything, and the massive wings required for all the weight of fuel coming with you…
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