News4 mins ago
Escaping Earth's Gravity
Can anyone explain to me (without posting links...often cant understand links) how NASA footage shows us escaping Earth's gravity very slowly with rather tall rockets on take off (Apollo missions etc).
Most of us have experienced escaping Earth's gravity by a *horizontal* take of in a plane and then slowly climbing as speed increases.
And most of us have experienced a (bonfire night) rocket, taking off *vertically* , at great speeds in order to get in to the air.
Common sense tells me that something tall (ie, a rocket,) will fall flat on its face if it isnt blasted off at enough force, so why do all the space programmes that I see, show impossible take offs?
Most of us have experienced escaping Earth's gravity by a *horizontal* take of in a plane and then slowly climbing as speed increases.
And most of us have experienced a (bonfire night) rocket, taking off *vertically* , at great speeds in order to get in to the air.
Common sense tells me that something tall (ie, a rocket,) will fall flat on its face if it isnt blasted off at enough force, so why do all the space programmes that I see, show impossible take offs?
Answers
The Saturn V is doing over 100mph before it clears the tower. That's fast, anyway in most cases they are not trying to beat gravity, merely trying to achieve freefall orbit. No one has really escaped the earths gravity, even the moon landings remained in the gravity well. Escape velocity is pprox 25000mph so it would be quite possible for many space craft to...
22:40 Sun 12th Apr 2015
It's very big and very heavy.
As long as the thrust is accurately vertical (which it will be designed to be) conservation of momentum will keep it upright as it accelerates. It will have all sorts of gimbals and sideways thrusters to help with this too.
It's not really that 'slow' either - just appears so because of the huge size of the rockets.
As long as the thrust is accurately vertical (which it will be designed to be) conservation of momentum will keep it upright as it accelerates. It will have all sorts of gimbals and sideways thrusters to help with this too.
It's not really that 'slow' either - just appears so because of the huge size of the rockets.
-- answer removed --
Not sure why you think that something tall should fall flat on its face. Crudely put, things fall over when their centre of gravity shifts outside their base. It's difficult to find accurate information about the speed of take-off of the shuttle, but the consensus seems to be that by the time the rocket clear the tower, it's travelling at somewhere between 70 - 140 mph, which is probably somewhat faster than a firework rocket.
It's also a fair bet to assume that the manufacturing tolerance of the vehicle and its engines are a few orders of magnitude tighter than those of a firework. Plus, of course, it doesn't have a stick on one side!
It's also a fair bet to assume that the manufacturing tolerance of the vehicle and its engines are a few orders of magnitude tighter than those of a firework. Plus, of course, it doesn't have a stick on one side!
The rocket starts slowly and speed increases until it is going fast enough to reach space. The speed needed to get into space is called 'escape velocity' as it is the speed needed to 'escape gravity'.
There has to be a limit to the acceleration of the rocket or anyone on board would be killed by the 'G' force. You could not have a gigantic gun for example with the crew inside a sort of hollow bullet that went from 0 to 800mph in a tiny fraction of a second ( as a rifle bullet does) the crew would be reduced to a pulp. The acceleration has to be gradual so that the crew can survive it, this is normally achieved by using a 3 stage rocket , only the 3rd stage actually reachs space, the much larger 1st and 2nd stage just increase the speed so that the final stage can reach escape velocity.
There has to be a limit to the acceleration of the rocket or anyone on board would be killed by the 'G' force. You could not have a gigantic gun for example with the crew inside a sort of hollow bullet that went from 0 to 800mph in a tiny fraction of a second ( as a rifle bullet does) the crew would be reduced to a pulp. The acceleration has to be gradual so that the crew can survive it, this is normally achieved by using a 3 stage rocket , only the 3rd stage actually reachs space, the much larger 1st and 2nd stage just increase the speed so that the final stage can reach escape velocity.
The Saturn V is doing over 100mph before it clears the tower. That's fast, anyway in most cases they are not trying to beat gravity, merely trying to achieve freefall orbit. No one has really escaped the earths gravity, even the moon landings remained in the gravity well. Escape velocity is pprox 25000mph so it would be quite possible for many space craft to actually leave the well but that is not usually the mission.
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