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 Post Posted: Mon Apr 09, 2018 3:01 pm 
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Location: East of the West, west of the East, north of the South, south of the North Pole.
Lord Golbez wrote:
If you can throw a sword into orbit, you can definitely throw a sword out of orbit.

You can't throw an object into orbit no matter what.

First there's the problem of air resistance. Aerobraking is useful when you want to go down, but it's a problem when you want to go up. Random objects like swords would be affected by the same forces that cause satellites to burn up on reentry. Orbital speed is higher than the speed of sound, and a non-aerodynamic object simply can't go faster than sound trough air. (Unless you give it such immense kinetic energy that it just punches a hole in the atmosphere, but that would be too fast. You wanted to throw it into orbit, not all the way out of the solar system.)

But what if you manage to make a javelin so extremely aerodynamic that it can be thrown clear out of the atmosphere? As long as it doesn't reach escape velocity it will follow an elliptical trajectory that passes through the point where it last stopped accelerating. If you threw the javelin at an upward angle, then this ellipse passes trough the Earth, and is therefore not an orbit. You could try throwing the javelin parallel to the ground. It will then pass through much more air than if it were thrown upwards, and thus be slowed down more, but if it's really extremely super-aerodynamic you might manage to get it into a trajectory that doesn't hit the ground. None the less it will return to where it stopped accelerating, which is the point where air resistance became negligible. That means that after less than one full orbit the javelin will enter the atmosphere again and be subjected to more air resistance. Even if it makes it out a second time it will have lower speed, and before long it will fall back to the ground.

To get an object into an orbit that stays out of the atmosphere you must accelerate it after it has left the atmosphere. There is no way to do that by throwing it from the ground.

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 Post Posted: Mon Apr 09, 2018 11:02 pm 
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Joined: Tue Aug 22, 2006 4:50 pm
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Yes, I can.

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 Post Posted: Thu Apr 12, 2018 10:24 am 
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Joined: Tue Jun 03, 2014 5:44 am
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Lord Golbez wrote:
Yes, I can.


Me too. Been there, done that.

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