Space Flight

http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation describes pretty well how a rocket works in vacuum.

This makes it work into vacuum.

None of that makes a rocket work in a vacuum.

If you say it doesn't work in a vacuum, then following my post, it shouldn't work in the atmosphere either, since for the rocket it makes no difference. Yet we both know it works in air just fine. So it works in a vacuum too.

Quote from: Shmeggley on June 03, 2013, 09:48:48 AM

Quote from: sceptimatic on June 03, 2013, 09:45:01 AM

Quote from: icanbeanything on June 03, 2013, 09:12:09 AM

Quote from: sceptimatic on June 03, 2013, 08:01:38 AM

Anyway, I have no problems with this but  the release from a breach would be the same....no motion of the rocket. It would be a dud.

The release from the breach would be a jet of gas shooting out of the box/rocket, which would behave the same way as it does in air. My point with the pressure difference was basically that from the point of view of the rocket, the exhaust gas is of such high pressure that it makes no difference whether there's air or a vacuum around the rocket; since the difference in pressure is nearly the same, there's only a 15 psi difference, the atmosphere around the rocket is so thin compared to the rocket exhaust that it might as well be a vacuum. Just like for us humans, the pressure up 120,000 feet high, while not zero, might as well not exist and be called a vacuum since it's so thin.

How you can believe that a rockets gases would behave the same on earth as in space is beyond me.

So you think that the law of conservation of momentum, which is a demonstrable fact, applies only on Earth's surface but not above the atmosphere?

When have I said this?

You've just implied that, because you suggest that a rocket should behave differently on Earth and in space. Rockets work by the law of conservation of momentum, which is supposed to be universal. So if you say that they shouldn't work in space then the law would have to be violated in space or for some reason not apply in space.

You have said in these forums that you believe in Newton's laws of motion. The law of conservation of momentum is implied in Newton's laws. So would you like to retract that you believe in Newton's laws or admit that a rocket must work the same wherever it is? That is, it has the same amount of thrust on Earth as in space.

Can someone draw a nice little force diagram for scepti so that he can understand just what is really propelling a rocket?   The fuel turns from solid or liquid into a gas, made up of very tiny particles being accelerated very quickly.   There was so net force before and there has to be zero net force after.   Since these particles were stored in the rocket, when they are accelerated out the rocket exhaust, they must also accelerate the rocket.   One particle accelerates the rocket a miniscule amount,  but there are billions of these particles being ejected during the burn,  causing the rocket to accelerate.  Someone brought up a shotgun analogy which is very appropriate.   The rocket acts like a shotgun that is being fired continuously,  ejecting thousands of particles every fraction of a second.

Can someone draw a nice little force diagram for scepti so that he can understand just what is really propelling a rocket?   The fuel turns from solid or liquid into a gas, made up of very tiny particles being accelerated very quickly.   There was so net force before and there has to be zero net force after.   Since these particles were stored in the rocket, when they are accelerated out the rocket exhaust, they must also accelerate the rocket.   One particle accelerates the rocket a miniscule amount,  but there are billions of these particles being ejected during the burn,  causing the rocket to accelerate.  Someone brought up a shotgun analogy which is very appropriate.   The rocket acts like a shotgun that is being fired continuously,  ejecting thousands of particles every fraction of a second.

Scintific already posted pressure diagrams of a rocket chamber a few pages back. I guess they didn't work.

Quote from: sceptimatic on June 03, 2013, 03:33:29 AM

Quote from: Scintific Method on June 03, 2013, 03:25:46 AM

Quote from: sceptimatic on June 03, 2013, 02:55:15 AM

When rockets fire lead shot or ball bearings or even bowling balls from an enclosed chamber, then we can discuss that.
For now, we need to concentrate on rockets "burning" fuel.

Don't you get it? It doesn't matter what is being accelerated, it's a case of how much and how fast.

Rockets expel a far greater mass of gas than a shotgun does of shot, and they expel it at far greater speed too. To achieve that speed, the gas has to be accelerated, which happens inside the rocket (just like the shot is accelerated inside the shotgun). The gas is accelerated toward the exhaust, as that is it's only means of escape, so the rocket is accelerated by a proportional amount in the opposite direction.

Yes, the gas expands rapidly into the vacuum, but it has already done it's work, so that expansion is irrelevant.

If it's a question of retaining the fuel so that it can burn, then all you need to realise is that it takes time for the burnt gasses to expand out of the way, in the meantime they act like a plug, allowing the remaining fuel to burn at a steady rate. When the rocket is not required, internal valves shut off the flow of fuel.

Oh, I get it. No offence to you but you do not get it.

The fuel in your rocket does no work at all until it is expelled from the rockets rear end. On earth, the work is done when it pushes against the atmosphere, "expanding" into it and the atmosphere pushes right back.
In space, you can have a billion ton rocket and it's fuel will expand into space, doing no work, because space will just accept it and beg for more.
The rocket in a vacuum is useless.

Ok, you don't get it. Let me try putting this another way:

Yes, the burning fuel expands into space. Rapidly. But space is only available in one direction: the exhaust. In all other directions, there is the rocket's nozzle. Here's a nice simple diagram of a combustion chamber and nozzle:



The arrow pointing right represents the escaping gas, the little arrows all around represent the pressure exerted by the gas on the inside of the combustion chamber and nozzle, and the arrow pointing left represents the net resultant force pushing the rocket along.

Actually, I have a question for any actual rocket scientists on here: given that rockets work on a pressure differential, wouldn't that make them more effective in a vacuum?

According to what I read, yes, jet propulsion effectiveness is inveresly proportional to the viscosity of the medium it is working through.

Quote from: Shmeggley on June 03, 2013, 10:44:31 AM

Quote from: sceptimatic on June 03, 2013, 10:26:48 AM

Quote from: Shmeggley on June 03, 2013, 09:48:48 AM

Quote from: sceptimatic on June 03, 2013, 09:45:01 AM

Quote from: icanbeanything on June 03, 2013, 09:12:09 AM

Quote from: sceptimatic on June 03, 2013, 08:01:38 AM

Anyway, I have no problems with this but  the release from a breach would be the same....no motion of the rocket. It would be a dud.

The release from the breach would be a jet of gas shooting out of the box/rocket, which would behave the same way as it does in air. My point with the pressure difference was basically that from the point of view of the rocket, the exhaust gas is of such high pressure that it makes no difference whether there's air or a vacuum around the rocket; since the difference in pressure is nearly the same, there's only a 15 psi difference, the atmosphere around the rocket is so thin compared to the rocket exhaust that it might as well be a vacuum. Just like for us humans, the pressure up 120,000 feet high, while not zero, might as well not exist and be called a vacuum since it's so thin.

How you can believe that a rockets gases would behave the same on earth as in space is beyond me.

So you think that the law of conservation of momentum, which is a demonstrable fact, applies only on Earth's surface but not above the atmosphere?

When have I said this?

You've just implied that, because you suggest that a rocket should behave differently on Earth and in space. Rockets work by the law of conservation of momentum, which is supposed to be universal. So if you say that they shouldn't work in space then the law would have to be violated in space or for some reason not apply in space.

To gain conservation of momentum in space, you first have to get the rocket to work.

It's the rocket that works by the laws of physics, not the other way round.

Anyway, I'm getting tired of this. You're reverting to the same statements you said three pages ago, and I won't post the same arguments twice, if all you do is ignore them.

I see there's no convincing you until you hop on a rocket yourself. I do hope that will happen within our lifetime.

Quote from: Fizzy Logic on June 03, 2013, 07:42:11 AM

http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation describes pretty well how a rocket works in vacuum.

This makes it work into vacuum.

Please read and work a little bit before stating stupid things.

A rocket cannot work against its own fuel, unless that fuel is expended (key word) "against" something.

For the sixth time, that's not how a rocket works. I've said this repeatedly in this thread and even explained why, but you just keep posting the same statement.

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.

Your knowledge of rockets not working in vacuum comes from a misunderstanding of how rockets work in general.

Quote from: icanbeanything on June 03, 2013, 11:10:01 AM

Quote from: sceptimatic on June 03, 2013, 11:07:29 AM

Quote from: Shmeggley on June 03, 2013, 10:44:31 AM

Quote from: sceptimatic on June 03, 2013, 10:26:48 AM

Quote from: Shmeggley on June 03, 2013, 09:48:48 AM

Quote from: sceptimatic on June 03, 2013, 09:45:01 AM

Quote from: icanbeanything on June 03, 2013, 09:12:09 AM

Quote from: sceptimatic on June 03, 2013, 08:01:38 AM

Anyway, I have no problems with this but  the release from a breach would be the same....no motion of the rocket. It would be a dud.

The release from the breach would be a jet of gas shooting out of the box/rocket, which would behave the same way as it does in air. My point with the pressure difference was basically that from the point of view of the rocket, the exhaust gas is of such high pressure that it makes no difference whether there's air or a vacuum around the rocket; since the difference in pressure is nearly the same, there's only a 15 psi difference, the atmosphere around the rocket is so thin compared to the rocket exhaust that it might as well be a vacuum. Just like for us humans, the pressure up 120,000 feet high, while not zero, might as well not exist and be called a vacuum since it's so thin.

How you can believe that a rockets gases would behave the same on earth as in space is beyond me.

So you think that the law of conservation of momentum, which is a demonstrable fact, applies only on Earth's surface but not above the atmosphere?

When have I said this?

You've just implied that, because you suggest that a rocket should behave differently on Earth and in space. Rockets work by the law of conservation of momentum, which is supposed to be universal. So if you say that they shouldn't work in space then the law would have to be violated in space or for some reason not apply in space.

To gain conservation of momentum in space, you first have to get the rocket to work.

It's the rocket that works by the laws of physics, not the other way round.

Anyway, I'm getting tired of this. You're reverting to the same statements you said three pages ago, and I won't post the same arguments twice, if all you do is ignore them.

I see there's no convincing you until you hop on a rocket yourself. I do hope that will happen within our lifetime.

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.
You and others have been duped by the lies they tell you.

The "fact" that you don't understand how rockets work is not really helping your argument.

The wiki link is just the tip of the iceberg. I you'd look, you'll find more evidence to support my claims.

Quote from: Shmeggley on June 03, 2013, 11:18:40 AM

Quote from: sceptimatic on June 03, 2013, 11:13:35 AM

Quote from: icanbeanything on June 03, 2013, 11:10:01 AM

Quote from: sceptimatic on June 03, 2013, 11:07:29 AM

Quote from: Shmeggley on June 03, 2013, 10:44:31 AM

Quote from: sceptimatic on June 03, 2013, 10:26:48 AM

Quote from: Shmeggley on June 03, 2013, 09:48:48 AM

Quote from: sceptimatic on June 03, 2013, 09:45:01 AM

Quote from: icanbeanything on June 03, 2013, 09:12:09 AM

Quote from: sceptimatic on June 03, 2013, 08:01:38 AM

Anyway, I have no problems with this but  the release from a breach would be the same....no motion of the rocket. It would be a dud.

The release from the breach would be a jet of gas shooting out of the box/rocket, which would behave the same way as it does in air. My point with the pressure difference was basically that from the point of view of the rocket, the exhaust gas is of such high pressure that it makes no difference whether there's air or a vacuum around the rocket; since the difference in pressure is nearly the same, there's only a 15 psi difference, the atmosphere around the rocket is so thin compared to the rocket exhaust that it might as well be a vacuum. Just like for us humans, the pressure up 120,000 feet high, while not zero, might as well not exist and be called a vacuum since it's so thin.

How you can believe that a rockets gases would behave the same on earth as in space is beyond me.

So you think that the law of conservation of momentum, which is a demonstrable fact, applies only on Earth's surface but not above the atmosphere?

When have I said this?

You've just implied that, because you suggest that a rocket should behave differently on Earth and in space. Rockets work by the law of conservation of momentum, which is supposed to be universal. So if you say that they shouldn't work in space then the law would have to be violated in space or for some reason not apply in space.

To gain conservation of momentum in space, you first have to get the rocket to work.

It's the rocket that works by the laws of physics, not the other way round.

Anyway, I'm getting tired of this. You're reverting to the same statements you said three pages ago, and I won't post the same arguments twice, if all you do is ignore them.

I see there's no convincing you until you hop on a rocket yourself. I do hope that will happen within our lifetime.

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.
You and others have been duped by the lies they tell you.

The "fact" that you don't understand how rockets work is not really helping your argument.

I know exactly how they work and my argument stands 100%. Rockets do not work in a vacuum.

Any data to back this?

If you used even an ounce of common sense you would realize rockets don't require anything for them to push against.   Air is incredibly free flowing and provides very little resistance.   It is a terrible material for something that requires to push on matter to move,  such as a human body.

Quote from: icanbeanything on June 03, 2013, 11:15:31 AM

Quote

A rocket cannot work against its own fuel, unless that fuel is expended (key word) "against" something.

For the sixth time, that's not how a rocket works. I've said this repeatedly in this thread and even explained why, but you just keep posting the same statement.

Quote

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.

Your knowledge of rockets not working in vacuum comes from a misunderstanding of how rockets work in general.

Your logic is how they work is missing. Sorry to say that but it is.
Don't read the crap, use your common sense.

I did use my common sense while explaining it to you, you may wish to re-read my posts two pages back.

He has no common sense and he doedńt rely on science! Is there any hope?

Quote from: icanbeanything on June 03, 2013, 11:32:38 AM

Quote from: sceptimatic on June 03, 2013, 11:18:29 AM

Quote from: icanbeanything on June 03, 2013, 11:15:31 AM

Quote

A rocket cannot work against its own fuel, unless that fuel is expended (key word) "against" something.

For the sixth time, that's not how a rocket works. I've said this repeatedly in this thread and even explained why, but you just keep posting the same statement.

Quote

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.

Your knowledge of rockets not working in vacuum comes from a misunderstanding of how rockets work in general.

Your logic is how they work is missing. Sorry to say that but it is.
Don't read the crap, use your common sense.

I did use my common sense while explaining it to you, you may wish to re-read my posts two pages back.

You are basically saying that a rocket actually pushes itself. Think about what you are saying man.

He's saying that the momentum of the escaping gases is equal and opposite to the momentum of the rocket. If you want to deny Newton's third law, please go ahead.

Quote from: Shmeggley on June 03, 2013, 11:43:27 AM

Quote from: sceptimatic on June 03, 2013, 11:37:25 AM

Quote from: icanbeanything on June 03, 2013, 11:32:38 AM

Quote from: sceptimatic on June 03, 2013, 11:18:29 AM

Quote from: icanbeanything on June 03, 2013, 11:15:31 AM

Quote

A rocket cannot work against its own fuel, unless that fuel is expended (key word) "against" something.

For the sixth time, that's not how a rocket works. I've said this repeatedly in this thread and even explained why, but you just keep posting the same statement.

Quote

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.

Your knowledge of rockets not working in vacuum comes from a misunderstanding of how rockets work in general.

Your logic is how they work is missing. Sorry to say that but it is.
Don't read the crap, use your common sense.

I did use my common sense while explaining it to you, you may wish to re-read my posts two pages back.

You are basically saying that a rocket actually pushes itself. Think about what you are saying man.

He's saying that the momentum of the escaping gases is equal and opposite to the momentum of the rocket. If you want to deny Newton's third law, please go ahead.

But...but...they don't quite use Newtons 3rd law do they.

But if you take a 400 kg rocket full of 100 kg of fuel, starting from zero momentum, then ignite the fuel and expel it all from the end of the rocket at 100 m/s, then by Newton's 3rd law the rocket has to be going at 25 m/s (if I calculated all that right) in the opposite direction you shot the fuel. Nobody is using Newton's 3rd law, it just describes what must happen in this situation.

Quote from: icanbeanything on June 03, 2013, 11:10:01 AM

Quote from: sceptimatic on June 03, 2013, 11:07:29 AM

Quote from: Shmeggley on June 03, 2013, 10:44:31 AM

Quote from: sceptimatic on June 03, 2013, 10:26:48 AM

Quote from: Shmeggley on June 03, 2013, 09:48:48 AM

Quote from: sceptimatic on June 03, 2013, 09:45:01 AM

Quote from: icanbeanything on June 03, 2013, 09:12:09 AM

Quote from: sceptimatic on June 03, 2013, 08:01:38 AM

Anyway, I have no problems with this but  the release from a breach would be the same....no motion of the rocket. It would be a dud.

The release from the breach would be a jet of gas shooting out of the box/rocket, which would behave the same way as it does in air. My point with the pressure difference was basically that from the point of view of the rocket, the exhaust gas is of such high pressure that it makes no difference whether there's air or a vacuum around the rocket; since the difference in pressure is nearly the same, there's only a 15 psi difference, the atmosphere around the rocket is so thin compared to the rocket exhaust that it might as well be a vacuum. Just like for us humans, the pressure up 120,000 feet high, while not zero, might as well not exist and be called a vacuum since it's so thin.

How you can believe that a rockets gases would behave the same on earth as in space is beyond me.

So you think that the law of conservation of momentum, which is a demonstrable fact, applies only on Earth's surface but not above the atmosphere?

When have I said this?

You've just implied that, because you suggest that a rocket should behave differently on Earth and in space. Rockets work by the law of conservation of momentum, which is supposed to be universal. So if you say that they shouldn't work in space then the law would have to be violated in space or for some reason not apply in space.

To gain conservation of momentum in space, you first have to get the rocket to work.

It's the rocket that works by the laws of physics, not the other way round.

Anyway, I'm getting tired of this. You're reverting to the same statements you said three pages ago, and I won't post the same arguments twice, if all you do is ignore them.

I see there's no convincing you until you hop on a rocket yourself. I do hope that will happen within our lifetime.

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.
You and others have been duped by the lies they tell you.

You either do not know what a fact is, or you are lying, or you have conducted experiments involving rocket technology in a vacuum and do not like to talk about it. 

Which is it?

Quote from: Rama Set on June 03, 2013, 11:57:15 AM

Quote from: sceptimatic on June 03, 2013, 11:13:35 AM

Quote from: icanbeanything on June 03, 2013, 11:10:01 AM

Quote from: sceptimatic on June 03, 2013, 11:07:29 AM

Quote from: Shmeggley on June 03, 2013, 10:44:31 AM

Quote from: sceptimatic on June 03, 2013, 10:26:48 AM

Quote from: Shmeggley on June 03, 2013, 09:48:48 AM

Quote from: sceptimatic on June 03, 2013, 09:45:01 AM

Quote from: icanbeanything on June 03, 2013, 09:12:09 AM

Quote from: sceptimatic on June 03, 2013, 08:01:38 AM

Anyway, I have no problems with this but  the release from a breach would be the same....no motion of the rocket. It would be a dud.

The release from the breach would be a jet of gas shooting out of the box/rocket, which would behave the same way as it does in air. My point with the pressure difference was basically that from the point of view of the rocket, the exhaust gas is of such high pressure that it makes no difference whether there's air or a vacuum around the rocket; since the difference in pressure is nearly the same, there's only a 15 psi difference, the atmosphere around the rocket is so thin compared to the rocket exhaust that it might as well be a vacuum. Just like for us humans, the pressure up 120,000 feet high, while not zero, might as well not exist and be called a vacuum since it's so thin.

How you can believe that a rockets gases would behave the same on earth as in space is beyond me.

So you think that the law of conservation of momentum, which is a demonstrable fact, applies only on Earth's surface but not above the atmosphere?

When have I said this?

You've just implied that, because you suggest that a rocket should behave differently on Earth and in space. Rockets work by the law of conservation of momentum, which is supposed to be universal. So if you say that they shouldn't work in space then the law would have to be violated in space or for some reason not apply in space.

To gain conservation of momentum in space, you first have to get the rocket to work.

It's the rocket that works by the laws of physics, not the other way round.

Anyway, I'm getting tired of this. You're reverting to the same statements you said three pages ago, and I won't post the same arguments twice, if all you do is ignore them.

I see there's no convincing you until you hop on a rocket yourself. I do hope that will happen within our lifetime.

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.
You and others have been duped by the lies they tell you.

You either do not know what a fact is, or you are lying, or you have conducted experiments involving rocket technology in a vacuum and do not like to talk about it. 

Which is it?

I've conducted rocket tests in a vacuum and I don't like to talk about it. Do you think I'm lying?

Of course I do.  I added on the third choice for completeness only.  Its perfectly obivous from your posting history you do not have a clue about how to go abou that.

Of course he is lying... But he can still prove us wrong by showing us his data.

Maybe we should tackle this from another angle and start with some basics.   Do you believe that matter is not destroyed when changing states from liquid to gas?

Quote from: icanbeanything on June 03, 2013, 11:32:38 AM

Quote from: sceptimatic on June 03, 2013, 11:18:29 AM

Quote from: icanbeanything on June 03, 2013, 11:15:31 AM

Quote

A rocket cannot work against its own fuel, unless that fuel is expended (key word) "against" something.

For the sixth time, that's not how a rocket works. I've said this repeatedly in this thread and even explained why, but you just keep posting the same statement.

Quote

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.

Your knowledge of rockets not working in vacuum comes from a misunderstanding of how rockets work in general.

Your logic is how they work is missing. Sorry to say that but it is.
Don't read the crap, use your common sense.

I did use my common sense while explaining it to you, you may wish to re-read my posts two pages back.

You are basically saying that a rocket actually pushes itself. Think about what you are saying man.

No, Scepti, I'm saying that the gas from the burned fuel is what pushes the rocket.

How about this: http://answers.yahoo.com/question/index?qid=20071110114103AAz61PN

Quote from: Rama Set on June 03, 2013, 12:05:54 PM

Quote from: sceptimatic on June 03, 2013, 12:04:34 PM

Quote from: Rama Set on June 03, 2013, 11:57:15 AM

Quote from: sceptimatic on June 03, 2013, 11:13:35 AM

Quote from: icanbeanything on June 03, 2013, 11:10:01 AM

Quote from: sceptimatic on June 03, 2013, 11:07:29 AM

Quote from: Shmeggley on June 03, 2013, 10:44:31 AM

Quote from: sceptimatic on June 03, 2013, 10:26:48 AM

Quote from: Shmeggley on June 03, 2013, 09:48:48 AM

Quote from: sceptimatic on June 03, 2013, 09:45:01 AM

Quote from: icanbeanything on June 03, 2013, 09:12:09 AM

Quote from: sceptimatic on June 03, 2013, 08:01:38 AM

Anyway, I have no problems with this but  the release from a breach would be the same....no motion of the rocket. It would be a dud.

The release from the breach would be a jet of gas shooting out of the box/rocket, which would behave the same way as it does in air. My point with the pressure difference was basically that from the point of view of the rocket, the exhaust gas is of such high pressure that it makes no difference whether there's air or a vacuum around the rocket; since the difference in pressure is nearly the same, there's only a 15 psi difference, the atmosphere around the rocket is so thin compared to the rocket exhaust that it might as well be a vacuum. Just like for us humans, the pressure up 120,000 feet high, while not zero, might as well not exist and be called a vacuum since it's so thin.

How you can believe that a rockets gases would behave the same on earth as in space is beyond me.

So you think that the law of conservation of momentum, which is a demonstrable fact, applies only on Earth's surface but not above the atmosphere?

When have I said this?

You've just implied that, because you suggest that a rocket should behave differently on Earth and in space. Rockets work by the law of conservation of momentum, which is supposed to be universal. So if you say that they shouldn't work in space then the law would have to be violated in space or for some reason not apply in space.

To gain conservation of momentum in space, you first have to get the rocket to work.

It's the rocket that works by the laws of physics, not the other way round.

Anyway, I'm getting tired of this. You're reverting to the same statements you said three pages ago, and I won't post the same arguments twice, if all you do is ignore them.

I see there's no convincing you until you hop on a rocket yourself. I do hope that will happen within our lifetime.

You can't convince me, because I know for a "fact" that rockets cannot work in a vacuum.
You and others have been duped by the lies they tell you.

You either do not know what a fact is, or you are lying, or you have conducted experiments involving rocket technology in a vacuum and do not like to talk about it. 

Which is it?

I've conducted rocket tests in a vacuum and I don't like to talk about it. Do you think I'm lying?

Of course I do.  I added on the third choice for completeness only.  Its perfectly obivous from your posting history you do not have a clue about how to go abou that.

Do you feel better now?

Quite.  Thanks!

You cannot understand even a simple explanation?

Can you just elaborate a little bit here, I think we might be getting somewhere.

I sure hope so, since I already elaborated on this same thing two pages back.

Basically, as the fuel burns, gas is generated inside the rocket's chamber. Savvy? This gas has a huge instantaneous pressure, pushing on the walls of the chamber, except for the exhaust nozzle, since there's no wall there to push against. This causes two things: ONE, the net force of the pressure pushes the rocket forward, since there is no force pushing against the exhaust nozzle of the rocket. TWO, the gas leaves the back of the rocket.

Notice that at no point in this was anything from the outside involved. The "pushing" of the rocket by the gas happens before the gas leaves the nozzle of the rocket, and before it has any chance to encounter air.

Quote from: icanbeanything on June 03, 2013, 12:45:59 PM

Quote from: sceptimatic on June 03, 2013, 12:25:26 PM

Can you just elaborate a little bit here, I think we might be getting somewhere.

I sure hope so, since I already elaborated on this same thing two pages back.

Basically, as the fuel burns, gas is generated inside the rocket's chamber. Savvy? This gas has a huge instantaneous pressure, pushing on the walls of the chamber, except for the exhaust nozzle, since there's no wall there to push against. This causes two things: ONE, the net force of the pressure pushes the rocket forward, since there is no force pushing against the exhaust nozzle of the rocket. TWO, the gas leaves the back of the rocket.

Notice that at no point in this was anything from the outside involved. The "pushing" of the rocket by the gas happens before the gas leaves the nozzle of the rocket, and before it has any chance to encounter air.

So basically what you are saying is. It's like someone in an alley way using their hands and feet to hoist themselves up by using the side walls as leverage . Is this what you are basically getting at, because this is how it seems to me.

Truly sorry if that's how it seems to you. I'm telling you it's not like that. But I don't see any other way to explain it. At this point only a live demonstration would work for you. Are there any physics universities nearby where you live? You could ask them if they have the time, to show you a vacuum chamber and allow you to put a balloon in it. See how it flies around in a vacuum.

By the way, as a technicality: the "vacuum" of outer space isn't really a perfect vacuum. It has some particles in it, and its pressure is above zero. Vacuum chambers can create much lower pressures than what is in space.

I don't know what space is. I'm going on what they tell us space is, as in a virtual vacuum...so basically I have to make my views based on that.
You won't see a balloon fly around in a vacuum, except when it goes pop..
The reason it will move then is because of the elasticity nothing more.

Your rocket in a vacuum will expend all of it's energy, (fuel) before it has the chance to do any work...which is to move the rocket.
By your reasoning, there is no legitimate reason for a rocket to ignite it's fuel in the vacuum of space..but they appear to do just that...why?

The reason is simple...rockets do not work in space, never have and likely never will.
We are on this earth and we stay on this earth....Nobody gets off and nobody gets on... it's our floor of the sky and anything that gets to live on it...grows on it.

The little tin things we send into the sky can go high and then fall back to earth.
The massive rockets like the Saturn V and the shuttle are all CGI and models.
Anything of that size with the fuel we use...would not leave the ground and would simply blow to smithereens if such a thing were possible to attempt to be made and fired up.

The launches we see in real time are simply ballistic missile launches that expend their fuel in minutes and are spent..to fall back into the sea, where they are picked up out of sight of prying eyes.

There is absolutely nothing man made in space...not even a screw.

You didn't answer my question... are there any universities in your area where you may find a vacuum chamber? I'm sure they'll let you put a balloon in it when the chamber is not in use for experiments. Just say it's for a YouTube experiment video of a balloon in vacuum. They'd most likely be happy to help.

The little tin things we send into the sky can go high and then fall back to earth.

So where's all the footage and witness accounts of them falling back to Earth right after launch? Again, such a huge rocket falling from the sky would definitely be impossible to cover up by NASA. Once more than 10 people see it, you're bound to have accounts of it. Not to mention if it falls next to a cruise line or, god forbid, over a city.

The university?

Back to my shotgun analogy: different weight loads recoil different amounts. This has nothing to do with pressure, as they all push on the same amount of air with the same amount of force. It has everything to do with the mass of the projectile(s) being propelled out of the barrel.

Again, this is direct evidence of Newton's 3rd law, which is what rockets operate on, and why they are more effective in a vacuum, not less. And before you say "yes, but rockets don't fire shot", realise that all matter (including gas) has mass, and the mass is what matters. (No pun intended!)

Oh, and going to a university and doing the balloon in a vacuum chamber experiment suggested by icanbeanything would be well worth your time. Just don't blow it up too full to start with.