Basically the post title, wouldn’t it be faster to go through the atmosphere at an angle instead of pushing up through the atmosphere? Is it possible to launch a spaceship this way?
I never took high school physics so this may be an exceptionally dumb question.
Edit: Thanks for all the explanations! I understand why now
In: Physics
Rockets need to get out of the atmosphere asap. There’s a lot more air between you and space going sideways than there is going upwards.
Planes don’t go to space. The shortest distance to space is straight up. It is possible but inefficient.
the most fuel efficient way to get out of earths atmosphere is to go straight up. you want to minimize the “burn time” b/c longer burn times mean more fuel. which means more weight and such.
Space craft don’t technically go straight up, they angle themselves into an orbital trajectory but it’s just much more gradual than an aircraft.
The reason they launch straight up is that all of a rockets lift is generated by thrust of it’s engines.
Planes meanwhile use the aerodynamic lift generated by their wings to stay afloat. The engines push the plane forward, which in turn moves air over the wings, which generates lift.
And before anyone says it, certain fighter jets etc have enough thrust that they can be entirely ballistic if they want, ie go straight up like a rocket.
The quickest way to get out of the atmosphere is to go straight up. Why do you believe it would be quicker to go at an angle? To get into orbit you need substantial velocity, and the atmosphere makes that more difficult, so job #1 is to get out of the atmosphere as quickly as possible using the shortest route (up), and THEN go sideways the build up the necessary velocity.
There’s 2 parts to getting into orbit. First you have to get out of the atmosphere obviously, but then you need to be travelling REALLY fast. Orbit speed is around 17,000 miles/hour depending on exactly how high you are. You make a full circle of the earth in about 1.5 hours. Getting up to that speed involves burning a LOT of fuel. If the space shuttle burned 1,000 tonnes of fuel getting into orbit I’d it was an easy launch.
So spending time in the atmosphere when you intend to accelerate to such crazy speeds is actually a bad idea. That’s a lot of drag that you just don’t want to deal with.
Honestly, the vertical launch itself burns fuel at varying rates so that as the shuttle puts in more effort as the air gets thinner to reduce drag.
To save fuel.
When you send up a spacecraft you don’t just have to go up, in fact the ‘up’ part is the easy part, you also have to accelerate to go faster. A lot faster.
You need to bring your spacecraft up to speeds that would be dozens of time the speed of sound down on the ground.
You also spend most of your rocket fuel on accelerating you rocket full of rocket fuel to go faster in the process.
Now you could accelerate horizontally near the ground and then move up, but near the ground there is a lot of air in the way.
Air resistance is a thing. The faster you go the more of a drag that atmosphere thing becomes.
Th easiest solution is to go up first and then wehn you are at higher altitude were there is less air in the way, you turn sideways and accelerate horizontally.
This of course is only an issue on places that have air. On the moon for example you only would need to be high enough to not run into any mountains before you started to accelerate sideways to get into orbit.
There are some experimental rocket designs that tried the whole horizontal start thing. One currently beingtested by Virgin (I think) is to starp a rocket under the wing of a 747, take the 747 up to high altitude and then let it go from there.
Taking of horizontally makes sense for planes because they fly by generating lift.
This is generated by having air moving over and under the wings at different rates, pushing the plane upwards.
Since lift requires air, it doesn’t make sense to put wings on a spaceship, since it can’t use lift in space.
Lift requires air so the higher you get, the less lift wings generate, since the air becomes thinner. So using lift to go to space isn’t an option either.
You need the massive power of rocket engines to reach space. And those are hard enough to steer if they start off pointed in roughly the right direction.
Taking of horizontally makes sense for planes because they fly by generating lift.
This is generated by having air moving over and under the wings at different rates, pushing the plane upwards.
Since lift requires air, it doesn’t make sense to put wings on a spaceship, since it can’t use lift in space.
Lift requires air so the higher you get, the less lift wings generate, since the air becomes thinner. So using lift to go to space isn’t an option either.
You need the massive power of rocket engines to reach space. And those are hard enough to steer if they start off pointed in roughly the right direction.
Airplanes go sideways because they use wings to create lift. Rockets go (mostly) vertically because they need to get away from earth’s surface and into orbit quickly because they can only carry so much fuel.
Going straight up gets you out of the atmosphere a lot faster than going sideways and slowly climbing. Also, the effectiveness of wings diminishes as the atmosphere thins, so the rocket would have to be going insanely fast while still in the atmosphere just to maintain lift. It’s far easier to just punch straight up, get out of the atmosphere, then establish an orbit.
Latest Answers