Does Rocketry Work beyond Earth's atmosphere?

[Heiwa]

Yes, the thrust of the rocket engine is proprotional to the mass of gas ejected out of the rocket (nozzle) into vacuum but also the velocity of the mass ejected (into vacuum).

This is why Moon travel doesn't work. You have to carry the mass (of fuel) with you from start and you simply get too heavy.

[arc300]

@Sceppy,
In your model it would seem that it is the nozzle itself and not the top/inner wall of the combustion chamber that bears the brunt of the thrust produced by the ambient atmosphere rushing back in to fill the void? That is, the rocket is being pushed by the nozzle? And if so, is it plausible that the nozzles on a Saturn 5 (for instance) can withstand an alleged 7.5 million pounds of thrust?

[simonshack]

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EARLIER CLUESFORUM POSTS RELEVANT TO THIS DEBATE

I'd like to remind all readers of/contributors to this thread about a few earlier forum posts relevant to this discussion. Back in April 2012, Cluesforum member 'hollycrap' pointed out the below Lee De Forest interview. It is interesting to note that De Forest, inventor of the Audion (a vacuum tube that takes relatively weak electrical signals and amplifies them) was a space travel skeptic while, on the other hand, firmly believed that transoceanic television would be possible with "the skillful location of relay stations" and by taking advantage of the waves reflected by the ionosphere. In other words - without the need for launching costly telecommunication satellites into orbit...



http://news.google.com/newspapers?id=KX ... %2C6595098

(Perhaps unsurprisingly, for all his achievements and in spite of being considered in his time as "the father of radio and television", De Forest never rose to international fame and died relatively poor, with just $1,250 in his bank account. Here's just how important his vacuum tube invention was: http://heinonline.org/HOL/LandingPage?c ... &id=&page= )

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In his following post, 'hollycrap' also mentioned the sticky problem of cold-welding in the vacuum of space:

Think we have stumbled across one of the best kept secrets about space :

Vacuum Welds

Drawing Bead On Space Peril
Boston Globe (1960-1979) - Boston, Mass.
Author: DONALD WHITE
Date: Sep 12, 1965
Start Page: A_44
Pages: 1
Text Word Count: 264

One of the hazards of space travel is a phenomenon known as cold welding. The vacuum of space causes metal to stick together, a tendency that could be catastrophic in a space craft.

http://pqasb.pqarchiver.com/boston/acce ... atl=google

Interestingly, Heiwa also wondered back then how anything could be lubricated in the void / vacuum of space:

It is a good question. How do you lubricate anything supposed to work in the void, empty universe or on a moon?

[sceppy]

@Sceppy,
In your model it would seem that it is the nozzle itself and not the top/inner wall of the combustion chamber that bears the brunt of the thrust produced by the ambient atmosphere rushing back in to fill the void? That is, the rocket is being pushed by the nozzle? And if so, is it plausible that the nozzles on a Saturn 5 (for instance) can withstand an alleged 7.5 million pounds of thrust?

The rocket doesn't exactly get pushed by the nozzle and there is no real stress on the rocket from atmospheric pressure other than it's own thrust, plus a low pressure friction to each side of it, which is created from its top as it speeds through the air above...deflecting the air, all down its sides but faster than the rocket is going against it.
I know , it sounds mad doesn't it?
The reason this happens, is due to the cone shaped top, 'deflecting' the air over it and making that air go faster, which is then clamped by the incoming denser air at the side...this is what's known as steadying the rocket in flight.
Hopefully I've explained this bit well enough. If not, I'll be glad to explain more.

Ok, so back to the thrusting gases from the nozzle:
The nozzle simply guides the expanding high pressure burning fuel into the dense atmosphere under it, whilst the centre part of the nozzle flame, is burning white hot...meaning it's at its most optimum heat.

So, you are close when you mention the nozzle but the nozzle is under new born baby stress. Basically no stress, because the hottest part of the flame is in the centre of it and the cooler parts are deflected, so the actual naked flame, doesn't directly apply anything other than friction heat.

The major fight happens all over, in stages, below the nozzle and it's a gas on air fight, all the way up.
The air fights back by suppressing the fire and pushing it back..basically, it's creating a barrier which is densest at the bottom...hence the dense clouds that get thinner and thinner until you see the flame.
It's a gradual process but nano second quick, if you get my meaning.

Remember one thing:
Air pressure has to stay constant at whatever level in the sky it's at. As in...it's 14.7 psi at sea level and it loses it's pressure 'slightly' as altitude is achieved.
Think of it like various weights of people all laid on top of each other. Heaviest at the bottom, being squashed by the lighter ones and the lighter ones being squashed by the even lighter ones, etc, etc, etc.

Now, whenever fire consumes atmosphere, it HAS to be replaced.
If you take away the foundations of a building, the floor above will fall on it.
In the terms of a rocket, it is replaced on all sides of the thrusting flame and also under it from it's widest point to it's hottest thinnest point.
The cooler the air, the denser and stronger it pushes (high pressure) and the hotter the air, the weaker but 'faster' it attacks to fill the void created by the exhaust flame.

It all boils down to even push, only slower and denser in quantity to faster and less denser and more speedier.
It's all action and equal and opposite reaction, all the way up.
The harder the thrust, the harder the fight.
All pressure must be equalized, it's the law of the earth but it can be cheated for a time, as in containing that pressure by forcing it into a steel 'strong' container and sealing it, or you can evacuate the same container of most...but not all of it's air pressure.

A perfect vacuum cannot be attained on earth with 'air' because there isn't a container strong enough, 'ever' to contain 'full' atmospheric pressure.
I can explain all this in finer detail if you are confused about any of this.

[Starbucked]

As the 'Vacuum of Space' would not have any aerodynamic "grip" on the surfaces of a spacecraft, what would stop it from rotating or wobbling uncontrollably even IF a rocket engine could prove thrust?

In other words:
Could it maintain alignment with the front moving forward and the engine remaining at the rear?

[sceppy]

As the 'Vacuum of Space' would not have any aerodynamic "grip" on the surfaces of a spacecraft, what would stop it from rotating or wobbling uncontrollably even IF a rocket engine could prove thrust?

In other words:
Could it maintain alignment with the front moving forward and the engine remaining at the rear?

In truth, in the real world. It wouldn't even get out of the dense atmosphere into thin air but lets say it did, by some magical way...then it would 'realistically' fall back to earth, because a vacuum is nothing...and nothing can float in a vacuum. It can only fall back into the closest gaseous place, which would be, earth.

[simonshack]

As the 'Vacuum of Space' would not have any aerodynamic "grip" on the surfaces of a spacecraft, what would stop it from rotating or wobbling uncontrollably even IF a rocket engine could prove thrust?

In other words:
Could it maintain alignment with the front moving forward and the engine remaining at the rear?

I would like to use my "waterjet funicular" once again to illustrate the problems related with a rocket reaching the higher levels of our atmosphere.

Imagine this funicular detached from that monorail - and just lying at the bottom of the ocean seabed, pointing upwards. As the powerful waterjet engine (such as those powering our modern high-speed ferries) is activated, the funicular would undeniably shoot up towards the ocean's surface at good speed :


As the funicular reaches and emerges out of the water surface, and so entering our (sea level) atmosphere density, it may perhaps proceed a little bit further upwards as long as its waterjet pump engine - and water propellant stored in its tank - provide enough thrust to make it rise up towards the sky. However, even if that water tank could, somehow, never run out of water, the sheer weight of the funicular would soon surpass the waterjet's ability to counter the forces of gravity. The funicular would, as you say, quickly start wobbling uncontrollably and plummet back down into the sea.

Now, you may ask: what if we (mankind) had the means to :

1: Build a waterjet so immensely powerful that it would keep the funicular rising up to the skies?

2: Constantly keep that tank full of water, so that the sole "recoil force" of its ejection would keep it airborne?

The problem is: mankind simply does not have these means. And the same goes for our rockets - who clearly work fine within our relatively dense atmosphere. The problem is, however powerful our rockets appear to be in our atmosphere, they will be faced with the very same sudden / or gradual power loss as that of my "waterjet funicular" - once they enter the void of space. The greatest NASA LIE is that air (our atmosphere) has NO ROLE in propelling their rockets forward.

[sceppy]

Absolutely correct, Simon.

[Heiwa]

A rocket engine fitted to a rocket is very simple. In the rocket is a fuel tank full of fuel. The fuel may be solid or liquid. It has a mass. By burning the fuel in the rocket engine combustion chamber, it becomes a hot gas that expands in the combustion chamber and in order no to blow up the rocket engine and the whole rocket, the hot gas or actually its mass is permitted to escape through a nozzle attached to the combustion chamber. By doing so, a thrust or force is applied to the rocket. The rocket loses mass in the process - burnt fuel/mass ejected one way producing a force driving the rocket the other way. Newton!
The comparison with a water jet on a funiculaire is stupid as a water jet is just a pump pumping water. 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.
Is Newton so difficult to understand? It has nothing to do with vacuum - it is only about an invisible force applied on a visible mass of any kind - solid, liquid or gas. To produce the invisible force is not easy, though. Drop an apple in a vacuum chamber and you will not see the force applied to the apple. But the apple drops. Newton explained why 400+ years ago. Or so.

[simonshack]

The comparison with a water jet on a funiculaire is stupid as a water jet is just a pump pumping water. But a water tank under high pressure is a good example.

Why is that comparison stupid, Heiwa?

Here's how the top manufacturers of waterjets describe them. Sounds like something you could have written yourself :

How a Waterjet Works



"A waterjet generates propulsive thrust from the reaction created when water is forced in a rearward direction. It works in relation to Newton's Third Law of Motion - "every action has an equal and opposite reaction". A good example of this is the recoil felt on the shoulder when firing a rifle, or the thrust felt when holding a powerful firehose."
http://www.hamjet.co.nz/hamiltonjet_wat ... rjet_works

Do you really think these waterjets produce less thrust than a watertank under high pressure? Would a watertank under high pressure propel a large ferry at a speed of 30 knots? Well, it might. But under what sort of pressure - and for how long ? Wouldn't that tank's pressure eventually run out after a few minutes - just like pressurized rocket propellant?

Instead, these waterjets can produce thrust forever - as long as they're kept below a ship's waterline, sucking water from the sea and thrusting it against the water behind the ship. Action/reaction. Newton, you know?

Yet, Newton never (could have) considered the specific conditions of space travel - where the active force "A" (jetflow pressure) produced against the reactive pressure "B" (atmospheric pressure) gradually loses its all-important counterpart "B" - such as when a rocket leaves our dense atmosphere. Is this so difficult to comprehend? To say that "rockets do not interact with the surrounding air" is akin to say that that our atmosphere has no force at all - and that air drag doesn't exist... If so, the years and billions spent by car and airplane manufacturers in wind tunnels to reduce their vessels' aerodynamic drag coefficients have all gone to waste !

[Vext Lynchpin]

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.

[Heiwa]

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?

[simonshack]

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?



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?

[sceppy]

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.

[Boethius]

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.