If you fly fast enough in one direction can you reach space?
Discussion
IainT said:
deeen said:
No, horizontal is a flat plane. Or should that be plan?
It's all relative.Horizontal.
A Plane.
Velocity
All are relative to something. As far as we experience it Horizontal could be relative to one's desk but is usually something considered at 90 degrees to vertical. i.e. goverened by gravity.
And straight is straight, irrespective of gravity... otherwise it would be curved, or something else, but not straight.
JonnyFive said:
Whilst we're on this topic, I assume this is how a Shuttle/Rocket takes off?
Crude but correct.Here is a long exposure picture of a Shuttle launch and you can see how the launch track gradually moves from the vertical to a more curved path. By the time the Shuttle has reached its orbital altitude (about 230 miles) and orbital speed (17,500 mph), it is following a curved path that precisely matches the curvature of the earth i.e. it is in orbit. It is falling towards the earth but forever misses the ground because the ground is falling away at the same rate as the Shuttle is descending towards it.
Edited by Eric Mc on Tuesday 11th January 11:45
Mr E said:
JonnyFive said:
Think OP means this;
Why bother going up first?Sufficiently large amount of initial shove = orbit or escape.
Wiki:
http://en.wikipedia.org/wiki/Space_gun#Practical_a...
Here's something the Iraqi's worked on:
http://en.wikipedia.org/wiki/Project_Babylon
In theory a space cannon would work. But there are a couple of problems with space cannons.
1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
2. As already mentioned, on a planet with an atmosphere, any object travelling much above 4,000 mph experiences such frictional heating by its passage through the air it would literally melt before it would get very far.
1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
2. As already mentioned, on a planet with an atmosphere, any object travelling much above 4,000 mph experiences such frictional heating by its passage through the air it would literally melt before it would get very far.
Edited by Eric Mc on Tuesday 11th January 12:28
Eric Mc said:
In theory a space cannon would work. But there are a couple of problems with space cannons.
1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
Not necessarily.1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
Some sort of long acceleration track could impart the required energy in a sustained shove, rather than a single bang and tens of thousands of G. You could coil it (snail shell style) to make it more compact, but then you may introduce acceleration that you've just worked hard to reduce.
Mr E said:
Eric Mc said:
In theory a space cannon would work. But there are a couple of problems with space cannons.
1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
Not necessarily.1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
Some sort of long acceleration track could impart the required energy in a sustained shove, rather than a single bang and tens of thousands of G. You could coil it (snail shell style) to make it more compact, but then you may introduce acceleration that you've just worked hard to reduce.
That idea has been around quite a long time and would work very well on an airless body - like our moon, other moons and asteroids.
It doesn't cure the problem of aerodynamic heating on a planet or moon with an atmosphere though. Once an object starts travelling faster than about 4,000 mph in an atmosphere, it's going to get very hot and eventually suffer structural failure and break up.
Edited by Eric Mc on Tuesday 11th January 13:09
Mr E said:
Eric Mc said:
In theory a space cannon would work. But there are a couple of problems with space cannons.
1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
Not necessarily.1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
Some sort of long acceleration track could impart the required energy in a sustained shove, rather than a single bang and tens of thousands of G. You could coil it (snail shell style) to make it more compact, but then you may introduce acceleration that you've just worked hard to reduce.
Eric Mc said:
Mr E said:
Eric Mc said:
In theory a space cannon would work. But there are a couple of problems with space cannons.
1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
Not necessarily.1. All the velicity required for orbit or gravitational escape has to ne imparted the instant the projectile starts up the barrel of the gun. That means massive accelerative forces are imparted on it in a millisecond of the explosive charge firing. Not many instruments can survive that type of instant acceleration - 0 to 25,000 mph (say) in a fraction of a second.
Certainly no living being could withstand it.
Some sort of long acceleration track could impart the required energy in a sustained shove, rather than a single bang and tens of thousands of G. You could coil it (snail shell style) to make it more compact, but then you may introduce acceleration that you've just worked hard to reduce.
That idea has been around quite a long time and would work very well on an airless body - like our moon, other moons and asteroids.
It doesn't cure the problem of aerodynamic heating on a planet or moon with an atmosphere though. Once an object starts travelling faster than about 4,000 mph in an atmosphere, it's going to get very hot and eventually suffer structural failure and break up.
Edited by Eric Mc on Tuesday 11th January 13:09
JonnyFive said:
mrmr96 said:
Munter said:
The words Project Babylon, Iraq and "Super Gun" spring to mind regarding this discussion.
That's probably because they are in my post which started this very train of discussion.
I knew I was getting Deja Vu
Munter said:
Eric Mc said:
If you have a means of propulsion which can operate in the vacuum of space (a rocket, essentially) then, yes, as long as thrust is constantly applied, the aircraft/rocket will keep climbing - and keep accelerating as well.
If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
Talking of escape velocities is confusing. Say I build a stack of bricks by standing on the top and hauling the bricks up using an electric motor. Eventually I could reach "space". Yet my velocity would be bugger all. Could a rocket with "unlimited" fuel not do the same thing? So long as it continues to move "up" even if only at 1 inch an hour, would it not eventually escape the earths pull? Why does it need those high speeds?If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
Oakey said:
Munter said:
Eric Mc said:
If you have a means of propulsion which can operate in the vacuum of space (a rocket, essentially) then, yes, as long as thrust is constantly applied, the aircraft/rocket will keep climbing - and keep accelerating as well.
If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
Talking of escape velocities is confusing. Say I build a stack of bricks by standing on the top and hauling the bricks up using an electric motor. Eventually I could reach "space". Yet my velocity would be bugger all. Could a rocket with "unlimited" fuel not do the same thing? So long as it continues to move "up" even if only at 1 inch an hour, would it not eventually escape the earths pull? Why does it need those high speeds?If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
I think it needs the speed because it doesn't have unlimited fuel? Its got to get to a massive speed and get out of the earths pull pretty sharpish before it burns for too long?
Oakey said:
Munter said:
Eric Mc said:
If you have a means of propulsion which can operate in the vacuum of space (a rocket, essentially) then, yes, as long as thrust is constantly applied, the aircraft/rocket will keep climbing - and keep accelerating as well.
If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
Talking of escape velocities is confusing. Say I build a stack of bricks by standing on the top and hauling the bricks up using an electric motor. Eventually I could reach "space". Yet my velocity would be bugger all. Could a rocket with "unlimited" fuel not do the same thing? So long as it continues to move "up" even if only at 1 inch an hour, would it not eventually escape the earths pull? Why does it need those high speeds?If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
You big chicken! Anyway I think what I'd missed was you need the speeds to get up and stay up. If you're going directly "up" and continue "up" physics allows you to go at any speed (but only if you can find a way to do it, and until you hit something or get trapped by something else's gravity). However if you want to get up and orbit without some continuous propulsion pushing away from the earth you need to be going at a speed fast enough horizontally that you "fail to fall".Now if we could attach a rope to a geo stationary satellite. What's to stop us running something up the cable slowly, and then "fireing" it off from there?
Oakey said:
Munter said:
Eric Mc said:
If you have a means of propulsion which can operate in the vacuum of space (a rocket, essentially) then, yes, as long as thrust is constantly applied, the aircraft/rocket will keep climbing - and keep accelerating as well.
If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
Talking of escape velocities is confusing. Say I build a stack of bricks by standing on the top and hauling the bricks up using an electric motor. Eventually I could reach "space". Yet my velocity would be bugger all. Could a rocket with "unlimited" fuel not do the same thing? So long as it continues to move "up" even if only at 1 inch an hour, would it not eventually escape the earths pull? Why does it need those high speeds?If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
http://en.wikipedia.org/wiki/Escape_velocity#Misco...
You could indeed build a column of bricks high enough such that you would eventually reach zero-g (escape velocity). This is usually thought of the other way around though, that is to say launching a satellite way out beond the geostationary point, and dropping a rope from it which can then be climbed by a "space elevator".
http://en.wikipedia.org/wiki/Space_elevator
http://en.wikipedia.org/wiki/Space_elevator
Zad said:
You could indeed build a column of bricks high enough such that you would eventually reach zero-g (escape velocity). This is usually thought of the other way around though, that is to say launching a satellite way out beond the geostationary point, and dropping a rope from it which can then be climbed by a "space elevator".
http://en.wikipedia.org/wiki/Space_elevator
I see. We can't make the rope yet. That'd explain why we're not doing that.http://en.wikipedia.org/wiki/Space_elevator
JonnyFive said:
Oakey said:
Munter said:
Eric Mc said:
If you have a means of propulsion which can operate in the vacuum of space (a rocket, essentially) then, yes, as long as thrust is constantly applied, the aircraft/rocket will keep climbing - and keep accelerating as well.
If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
Talking of escape velocities is confusing. Say I build a stack of bricks by standing on the top and hauling the bricks up using an electric motor. Eventually I could reach "space". Yet my velocity would be bugger all. Could a rocket with "unlimited" fuel not do the same thing? So long as it continues to move "up" even if only at 1 inch an hour, would it not eventually escape the earths pull? Why does it need those high speeds?If the speed achieved is less than 17,500 mph, once the engine thrust stops (which is bound to happen at some point - usually when the fuel is exhausted), the aircraft/rocket will immediately start slowing down and will eventually fall back to earth.
If a speed of 17,500 mph is achieved, the aircraft/rocket would go into orbit around the earth - even when the engine has shut down.
If a speed of 25,000 mph is achieved, earth's gravity will not be able to hold on to it and it will go into orbit around the sun.
If it achieves a velocity of 37,000 mph, even the sun won't be able to hold it back and it will head out of the solar system never to come back.
I think it needs the speed because it doesn't have unlimited fuel? Its got to get to a massive speed and get out of the earths pull pretty sharpish before it burns for too long?
In reality his column would start to bend, would it not? Not to mention at the top of it he'd be travelling at god knows how many mph.
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