Does Rocketry Work beyond Earth's atmosphere?

If NASA faked the moon landings, does the agency have any credibility at all? Was the Space Shuttle program also a hoax? Is the International Space Station another one? Do not dismiss these hypotheses offhand. Check out our wider NASA research and make up your own mind about it all.
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Vext Lynchpin
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Vext Lynchpin » Tue Jun 18, 2013 7:00 pm

I think the main point that the posters on this thread (who are more scientifically minded than I) have been making is that the vacuum itself exerts a force of its own that renders nil the force of the mass of gas escaping from a rocket's nozzle.

To use a simple analogy, think of a rocket and its escaping gas as an aerosol can full of silly string. When you press the button on the aerosol can, silly string is ejected at great speed. If there's enough speed, it may exert force on the aerosol can, so that the silly string is moving in one direction, and the can in the other. Newton.

But in a vacuum, the speed of the equalizing force of the vacuum is akin to someone pulling the silly string out of the aerosol can faster than it can be ejected, thus nullifying the force caused by the silly string's ejection.

Of course, the analogy isn't perfect, since pulling the silly string out would actually cause the aerosol can to move in the same direction as the pull. This wouldn't be a factor with gases being pulled into the vacuum.

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Heiwa » Tue Jun 18, 2013 7:01 pm

simonshack wrote:
Do you really think these waterjets produce less thrust than a watertank under high pressure?
I just say that a waterjet needs a pump, etc, etc, blah, blah. A watertank under pressure does not need a pump. And a watertank under pressure does not produce any thrust ... unless you open a valve attached to it and ... let the pressure out.

Simon - allow me to ask a question: Do you accept the findings of Newton?

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by simonshack » Tue Jun 18, 2013 7:15 pm

Heiwa wrote: Simon - allow me to ask a question: Do you accept the findings of Newton?
Heiwa, I do not think that question is warranted, given that I have repeatedly and respectfully referred to Newton's laws throughout this thread. You should know by now that I understand Newton's laws - and that what I am questioning are not Newton's laws - but NASA's fraudulent misuse of the same.

But since you asked me a question, and you have still not answered this one - which I have presented twice already, please do so now:

Does this graphic respect Newton's laws? Yes - or no?

Image

If mass A (50.000kg) were ejected at 8km/s from a mass B+rocket body (50.000kg) - would this not propel the rocket forward at 8km/s - as of Newton's laws? And just like a man throwing a pumpkin of his own weight away from him? If so, how is this very same result achieved in a vacuum with a small, trickling flow/mass of a rocket's exhaust expelled at a velocity of 4.4km/s - as claimed by NASA?

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by sceppy » Tue Jun 18, 2013 7:21 pm

Heiwa wrote: But a water tank under high pressure is a good example. Attach a fire hose to a valve of this tank and open the valve and see what happens! Aha, water at high pressure flows out of the hose at a certain rate mass per second and applies a force on the end of (and the whole) hose in the process. Newton.
It works as long as water flows out of the hose.


The reason a water hose works and pushes a fireman back, is the pressure of the jet of water against the air.The trick they try to play is by using the high pressure tank and the open nozzle to make it look like it's action and reaction from just this point but it's not.

You can very easily prove it's an action of dense powerful thrusting water against the reaction of a less dense atmosphere and here's how you can do it. First you need the high pressure hose and someone opposite you holding a 4ftx4ft board.(make sure you are both of similar weight).

First of all...pick out a spot to stand on and turn on the hose to it's fullest and see how much force it exerts on you. If you can stay on the spot you started with, then great but if not...reduce the pressure until you can stay on the spot but doing so, using your force.

From this point on, your action and reaction should, 'in theory' be over with, because the expelled water into the atmosphere is of no use, we are told. Now get the person with the board to go to the end of the water spray and hold up the board so the water is directly hitting it, then to walk towards you.

As he gets closer, he will feel himself getting pushed back but you will also feel yourself being forced from your spot.
Keep coming in closer and if you will end up being pushed from your spot, whilst the person with the board keeps forcing you back, as long as you can keep your water hose aimed at his board.

You are the rocket and your friend is the atmospheric barrier.
You can do it with a normal garden hose inside a tube, with the nozzle sticking out of the end, as well.
All you do is, get a hose and feed it through the tube or waste pipe and turn on the water pressure 'enough' so that the hose does not get pulled back from the edge of the waste pipe.
Now get a small board or use your hand and move it closer to the water jet and you will find that you push the hose back into the pipe using your hand against water only. Your hand being the atmosphere against the thrusting water/fuel.
Action/reaction, the proper way. :)

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Boethius » Tue Jun 18, 2013 7:45 pm

Vext Lynchpin wrote:I think the main point that the posters on this thread (who are more scientifically minded than I) have been making is that the vacuum itself exerts a force of its own that renders nil the force of the mass of gas escaping from a rocket's nozzle.

To use a simple analogy, think of a rocket and its escaping gas as an aerosol can full of silly string. When you press the button on the aerosol can, silly string is ejected at great speed. If there's enough speed, it may exert force on the aerosol can, so that the silly string is moving in one direction, and the can in the other. Newton.

But in a vacuum, the speed of the equalizing force of the vacuum is akin to someone pulling the silly string out of the aerosol can faster than it can be ejected, thus nullifying the force caused by the silly string's ejection.

Of course, the analogy isn't perfect, since pulling the silly string out would actually cause the aerosol can to move in the same direction as the pull. This wouldn't be a factor with gases being pulled into the vacuum.
Vext,

glad you're picking up on some of our slightly technical discussion. I would like to make one point that sometimes gets lost in the sauce: a vacuum is an effect, not a force. A force moves matter. A vacuum is the absence of matter and hence absence of pressure. I say this because some NASA-friendly sites accuse us doubters of claiming that space "sucks" the gas from the rocket, which is a misrepresentation of our position.


Here's an analogy for using rockets in a vacuum:


If someone told you they have a ship that moves across the surface of the Sun by shooting lots of ice cubes out of the back at very high speed would you think this plausible?

Of course not. The ship isn't going to move even if the ice cube generator can make a billion cubes a second. Every cube is instantly absorbed by the sun and all of the cube making energy goes to naught, is lost in the Sun.

That's essentially what would happen to liquid fueled space rocket. Gas has no effect in a vacuum. In fact, gas cannot exist in the vacuum of space any more than ice can on the surface of the Sun. NASA propaganda about "space clouds" notwithstanding.

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Flabbergasted » Tue Jun 18, 2013 8:18 pm

Heiwa wrote:Attach a fire hose to a valve of this tank and open the valve and see what happens! Aha, water at high pressure flows out of the hose at a certain rate mass per second and applies a force on the end of (and the whole) hose in the process. Newton.
It´s true there is recoil in a fire hose under high pressure, but while it is a nice illustration of recoil it is still not an appropriate analogy for a "recoil-driven" rocket.

On pains of saying the obvious, a fire hose is long, narrow, flexible and very light. The source of the pressurized water is a hydrant or truck which is fastened to the ground, in other words, it is fixed on a surface and independent of the hose.

A rocket is both "water truck" and "fire hose", all in one huge chunck.

When pressure is applied to a fire hose lying unattended on the ground, it jolts and dances like a bewitched snake. A man standing on the ground (in this case actually applying force against the ground) while trying to stabilize it and point it in one specific direction would definitely feel a recoil. But if the nozzle was simply mounted on the back of a 15-ton water truck, the recoil would be negligible at best, the truck would hardly vibrate, and a child could safely put his arm around it.

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Heiwa » Wed Jun 19, 2013 2:25 am

sceppy wrote:The reason a water hose works and pushes a fireman back, is the pressure of the jet of water against the air.
Can you pls illustrate above with a figure? Evidently there is an invisible friction force between the static air and the flowing water that has left the hose, but how does this invisible force apply to the fireman?
I have a feeling you do not know anything how a force works.

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Utah » Wed Jun 19, 2013 6:42 am

Heiwa wrote:
sceppy wrote:The reason a water hose works and pushes a fireman back, is the pressure of the jet of water against the air.
Can you pls illustrate above with a figure? Evidently there is an invisible friction force between the static air and the flowing water that has left the hose, but how does this invisible force apply to the fireman?
I have a feeling you do not know anything how a force works.
Hewia is right to point out that sceppy's statement does not make sense.

The reason a water hose works is that pressure behind the nozzle pushes water through the nozzle at increased velocity. The width of the nozzle is much smaller than the width of the hose, making for a large net force on the water as it leaves. The water is acclerated as it is forced out. Pressure forces the water forward through the nozzle at high speed; the water pushes back on the hose – this reaction makes the hose hard for the fireman to hold steady. Newton it is!

High school physics. Not that complicated.

With so many credible arguments against the feasilibity and reality of space travel, why peddle the bogus assertion that a hose (or a rocket) needs air to push against?

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by sceppy » Wed Jun 19, 2013 11:13 am

Heiwa wrote:
sceppy wrote:The reason a water hose works and pushes a fireman back, is the pressure of the jet of water against the air.
Can you pls illustrate above with a figure? Evidently there is an invisible friction force between the static air and the flowing water that has left the hose, but how does this invisible force apply to the fireman?
I have a feeling you do not know anything how a force works.
Molecules that make up air are always in an agitated state. It's just a case of how agitated depending on how hot or cold it is.
It's the reason why we feel hot or cold.
When we are cold...it's because the air molecules are slow and laboured all over our skin.
If it's hot weather...those molecules are as agitated as hell on your skin and it's that friction that heats you up to make you sweat to cool them down to a less agitated state.
I'm telling you this because most people do not understand the force of the atmospheric pressure we are living under and they pass it off as nothing.
I mean, we can wave our arms about, so what's the problem, right?
Well that's fine, because our bodies equalise that pressure and we are born with it around us, so we never give it the thought it deserves.
Now that's out of the way, I'll explain why the hose works against the atmosphere.

Oh... one more thing. I'll just explain what air pressure is and does.
As we know...air pressure is at 14.7 psi at sea level and the reason for this is because the air molecules are stacked on top of each other for miles and miles into the sky.
At sea level, the air molecules are compressed by the air molecules above them and so on and so on, until the air molecules at the top are basically left to run about like free range hens because there is very minimal compression force acting on them, so they can move around each other at fast pace.
This is known to us as thin air.

To really appreciate the power of atmospheric pressure at sea level, we can pressurise a container, or we can partially evacuate one, depending on it's strength.
So what happens when we put 1000 psi above atmospheric pressure into a sealed container?
Well first of all we have to remember that the empty container already had 14.7 psi inside it, when open to the air, because it was equalised in pressure, so the container is only under the stress of its own weight and make up.

Ok, so now it has 1000 psi extra inside it, which means, the molecules are squashed together like a bus full of kids with squashed faces against the windows of a bus.
In this state, the molecules are all fighting against each other, trying to push back against each other to get out of the way so they can regain their natural size but they find it hard, due to the amount squashed inside the container.
So where did that extra 1000 psi air come from that went into that container?
It came from the atmosphere at 14.7 psi and was squashed into a cylinder, so the atmosphere from above, has to naturally fill in the air that was taken...but how can it do this when the air is inside a solid container?

Because 1000 psi was taken from the air, it is replaced.
The thing to remember here,is...no matter what you do on earth or what happens...everything has to have an equaland opposite reaction to every action and it's the same with air.
You take 1000 psi from the air (action) and the air replaces as you take it (equal reaction to action).

If you compress 1000 psi of air molecules inside a container, the air outside will equalise that pressure over the outside surface area applying more volume of pressure at 14.7 psi.Or to put it simpler, there is an extra 1000 psi spread over the entire surface of the cylinder to equalise that pressure all pushing against it in a more agitated state than those inside.

A classic example is your common party balloon.
If you blow it up. The compressed air expands the balloon but the air molecules are squashed and because this balloon is attempting to defy sea level atmospheric pressure, then atmospheric pressure will equally concentrate and equal pressure against the pressure inside the balloon by becoming more pushy against the molecules that were taken from the atmosphere.

Hopefully this will be understood by all, because it's important to know the strength of what we live and breath under.
Ok, so let's get back to the fire hose because this trick is used to dupe people and it works well at first glance because it appears that it's correct in how rockets work so very few question it.
For all you logical thinkers (of which there are a lot of you) I'm 'hopefully' going to nail this once and for all in this post.

Rocket scientists would like us all to believe a rocket works like a fire hose. So let's grasp how one works how they say.
The water tank in the fire engine is pressurised and is sent to the hose... and as long as that hose nozzle is shut, the hose will simply hold the water pressure and that's it.There won't be any flopping about or anything like that.

Once the nozzle is open, the water pressure hits the inside of the thinner nozzle which forces the fireman back because there is more pressure coming at the nozzle than the nozzle will allow through, so, action and reaction forces the fireman back and that's why you see them struggling to hold the hose.
The above explanation is N.A.S.A 's supposed rocket and it sounds about right and very plausible doesn't it?...and we aren't rocket scientists so why question it, right?
Well first of all. The explanation for how the hose works, is an utter, pure, ridiculous load of horse shit. :D

Here's what really happens and bear in mind you need to get an understanding of atmospheric pressure in how I explained it.
For every action, there MUST be an equal and opposite reaction which includes water against atmosphere.

When the water leaves the hose under huge force, it hits the atmosphere and slightly fans out the further it goes, which is important, because the further the water stream goes, that's how much atmospheric pressure is working on it, plus the floor and the building it hits.
Because water is much denser than atmospheric air, it will naturally push that air out of the way much much more quickly... and the air wants to occupy the space what the water has taken, because it's atmospheric pressure has been altered.
Water in its dense state, naturally wants to be under the atmosphere , because it's heavier, yet because it falls naturally under it's own weight in the air, it allows the air to equalise the push against its weight, which is what you see from the stream of water.
So how can a water jet be pushed back by a so called piddly weak looking atmosphere, in simple terms?

Here is the nail in the coffin.
If you shoot water horizontally, you will notice it forms and arc.
This is the key to the fight back by the air, because the top of that water arc is the strongest force against the air, meaning the air has to push on it much harder to try and squeeze it to the ground because that water at the very top is moving horizontally and the water going either way from it is gradually falling, so the air compresses it from all around the water jet and tries to equalise it's own pressure... but in doing so, it forces the water both ways, because, as we know...water cannot be compressed but it can be forced away by exerting pressure, meaning one force hits the building or hits a crowd of rioters and the other force pushes the fireman back.

I'll put in this little diagram to show what I mean and hopefully what I've said will be grasped.

Image

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Flabbergasted » Wed Jun 19, 2013 11:29 am

Utah wrote:With so many credible arguments against the feasilibity and reality of space travel [...]
I agree. There are many compelling arguments against the feasilibity and reality of space travel. However, the question of whether rockets can actually work in the vacuum of space takes a certain precedence over the others.
Utah wrote:[...] why peddle the bogus assertion that a hose (or a rocket) needs air to push against?
The assertion that begs "unbogusing" is that immensely heavy rockets practically hover in the air over the launch pad, lifting off in slow motion, then gradually accelerate to 8 km/s (with no change in thrust) due to the same recoil principle at work in a shotgun, and not because they are pushing against something external.

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Heiwa » Wed Jun 19, 2013 1:01 pm

sceppy wrote: If you shoot water horizontally, you will notice it forms and arc.
This is the key to the fight back by the air, because the top of that water arc is the strongest force against the air, meaning the air has to push on it much harder to try and squeeze it to the ground because that water at the very top is moving horizontally and the water going either way from it is gradually falling, so the air compresses it from all around the water jet and tries to equalise it's own pressure... but in doing so, it forces the water both ways, because, as we know...water cannot be compressed but it can be forced away by exerting pressure, meaning one force hits the building or hits a crowd of rioters and the other force pushes the fireman back.
So the air applies a force on the flowing, spraying water particles that in turn applies a force on the fireman and the hose.

I agree that air applies a friction force on the water particles and that the result is that the water particles slow down and drop down on the ground - the latter by gravity force.
But the water particles have then left the hose/fireman and there is no connection between the water particles and the hose/fireman. So how can a friction force on a water particle created by the air be transmitted back to the hose/fireman?

Wouldn't it be easier for the water, leaving the hose, to apply a force on the hose, forgetting the air?

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by sceppy » Wed Jun 19, 2013 1:26 pm

sceppy wrote: If you shoot water horizontally, you will notice it forms and arc.
This is the key to the fight back by the air, because the top of that water arc is the strongest force against the air, meaning the air has to push on it much harder to try and squeeze it to the ground because that water at the very top is moving horizontally and the water going either way from it is gradually falling, so the air compresses it from all around the water jet and tries to equalise it's own pressure... but in doing so, it forces the water both ways, because, as we know...water cannot be compressed but it can be forced away by exerting pressure, meaning one force hits the building or hits a crowd of rioters and the other force pushes the fireman back.
Heiwa wrote: So the air applies a force on the flowing, spraying water particles that in turn applies a force on the fireman and the hose.

I agree that air applies a friction force on the water particles and that the result is that the water particles slow down and drop down on the ground - the latter by gravity force.
But the water particles have then left the hose/fireman and there is no connection between the water particles and the hose/fireman.
Heiwa wrote: So how can a friction force on a water particle created by the air be transmitted back to the hose/fireman?
The water is flying through the air and the 14.7 pounds per square inch of air pressure is wanting to occupy the space that the water is in, so it exerts an equal force all around the water which creates a friction and causes the water to push back towards the fireman and also towards whatever it's aimed at equally both ways.

Think of it like a person running at a running at a crowd of people with a long bamboo pole.
Once he hits those people and barges his weight and pole through some of them...he is hitting a friction barrier, which bends the bamboo pole and forces him back.

The long hose stream is like that bamboo pole going through a dense crowd, only the bamboo pole is the water stream and the crowd is the atmospheric pressure.

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Flabbergasted » Wed Jun 19, 2013 1:58 pm

sceppy wrote:Think of it like a person running at a running at a crowd of people with a long bamboo pole.
Once he hits those people and barges his weight and pole through some of them...he is hitting a friction barrier, which bends the bamboo pole and forces him back.
I think Heiwa is trying to say that the initial recoil is simultaneous with the opening of the nozzle, and so it is not really dependent on what the water does in the air. In fact, it seems to me you cannot come to an agreement about this firehose issue because you are talking about two different stages in the process.

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Heiwa » Wed Jun 19, 2013 2:02 pm

sceppy wrote: The water is flying through the air and the 14.7 pounds per square inch of air pressure is wanting to occupy the space that the water is in, so it exerts an equal force all around the water which creates a friction and causes the water to push back towards the fireman and also towards whatever it's aimed at equally both ways.

Think of it like a person running at a running at a crowd of people with a long bamboo pole.
Once he hits those people and barges his weight and pole through some of them...he is hitting a friction barrier, which bends the bamboo pole and forces him back.

The long hose stream is like that bamboo pole going through a dense crowd, only the bamboo pole is the water stream and the crowd is the atmospheric pressure.
So you really say that the air pushes the water stream back into the hose again and then apply a force on the fireman. :lol: Suggest you join some local volonter fire brigade and test your theory.

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by sceppy » Wed Jun 19, 2013 3:38 pm

Flabbergasted wrote:
sceppy wrote:Think of it like a person running at a running at a crowd of people with a long bamboo pole.
Once he hits those people and barges his weight and pole through some of them...he is hitting a friction barrier, which bends the bamboo pole and forces him back.
I think Heiwa is trying to say that the initial recoil is simultaneous with the opening of the nozzle, and so it is not really dependent on what the water does in the air. In fact, it seems to me you cannot come to an agreement about this firehose issue because you are talking about two different stages in the process.
The only two action/reaction processes in the firehose scene are the air pressure and water in the tank with hose nozzle closed...and water pressure from hose against the atmosphere with nozzle open.

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