Does Rocketry Work beyond Earth's atmosphere?

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Re: Why Rocketry Doesn't Work in the Vacuum

Postby lux on May 26th, 2013, 2:24 pm

Boethius wrote:For instance if you open a balloon at sea level the air seeps out slowly, based on pressure difference. If you want to empty the balloon faster you exert a force, press on the balloon and the air comes out faster. If you try to same experiment inside a vacuum you cannot press on the balloon to make the air come out faster, the air goes flying out of the balloon without any force, because the nature of the vacuum has already done all the work, for free, trying to equalize the pressure inside the vacuum with that inside the balloon.



This should be easy to prove with a vacuum chamber and an air-filled balloon remotely released within it.

Can you cite an example of such a proof being performed and offer some evidence of its legitimacy?
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby Boethius on May 26th, 2013, 2:31 pm

hoi.polloi wrote:That's also not really a philosophical reason first, as much as it is a scientific, physical reason first, Boethius.


On this point I disagree. Part of the philosophy of science is determining what results are even possible. For example, can you prove that all crows are black? In my opinion it is a philosophical question to say that man does not create new forces but only uncovers and harnesses existing ones. I could be proven wrong when tomorrow someone invents some unheard of force. As per my beliefs, if gas as it exists in nature cannot exert force upon objects in while inside of a vacuum I cannot see how a rocket made to operate in a vacuum, powered by gas, would work.

hoi.polloi wrote:Please explain why you haven't addressed lux's point before you go into any Goddard research first, if you please. He's already asked you twice. Why shouldn't gas be considered capable of accomplishing work, since it does indeed have mass?

I will address Lux's questions.

hoi.polloi wrote:Furthermore, what makes you so confident in Cassini's alleged discoveries of water plumes? Did they fire that explorer encased in several feet of lead to survive the journey to Enceladus? And why would you say a plume of gas fires 500km rather than over 500km?


I am giving NASA more than a fair chance :D . If I disregard the Cassini data then out goes the whole idea of gas jets existing naturally in space. If there are no instances in nature of gas moving objects through the vacuum of space either on why would we believe that we could create such a force?
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby Boethius on May 26th, 2013, 2:35 pm

lux wrote:
Boethius wrote:For instance if you open a balloon at sea level the air seeps out slowly, based on pressure difference. If you want to empty the balloon faster you exert a force, press on the balloon and the air comes out faster. If you try to same experiment inside a vacuum you cannot press on the balloon to make the air come out faster, the air goes flying out of the balloon without any force, because the nature of the vacuum has already done all the work, for free, trying to equalize the pressure inside the vacuum with that inside the balloon.



This should be easy to prove with a vacuum chamber and an air-filled balloon remotely released within it.

Can you cite an example of such a proof being performed and offer some evidence of its legitimacy?


If I only had a vacuum chamber....
The principle of free expansion is justified theoretically and proven experimentally. I have left many links in my posts describing both.

Did you understand the point about the false analogy of all of these "I throw this or that and off I go" rocket thrust demonstrations?
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby hoi.polloi on May 26th, 2013, 2:44 pm

However, if the explosion happens within a non-vacuum chamber, the concussive force is utilized, then the very next instant the explosion is exposed to vacuum, causing the entire chamber to be emptied with no work; and then the chamber is re-pressurized and more gas is added to create the next explosion — and all this is done at such a tremendous pace and with such precision that the vacuum never enters the equation except to eject the used explosion, could this different kind of engine function to propel the contraption surrounded by vacuum?
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Re:

Postby Boethius on May 26th, 2013, 2:46 pm

lux wrote:
Boethius wrote:Tom Wolfe's book "The Right Stuff" documents high altitude flight tests with rocket powered aircraft that would invariably fail in the thin air and plummet back to earth.


Could you provide an excerpt on this, Boethius?


Rather than pull the quotes from Wolfe's book which I read many years ago here are the details of his crash in the NF-104A aircraft which failed at an altitude of 21 miles.

http://www.check-six.com/Crash_Sites/NF ... h_site.htm

lux wrote:Otherwise, please consider: Don't nearly all rockets plummet back to Earth?


My suspicion is that all rockets are ballistic, that is they go up and down based on Newtonian mechanics and that the idea that they can produce force outside of the atmosphere is a fantasy/dream.
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby Boethius on May 26th, 2013, 3:31 pm

hoi.polloi wrote:However, if the explosion happens within a non-vacuum chamber, the concussive force is utilized, then the very next instant the explosion is exposed to vacuum, causing the entire chamber to be emptied with no work; and then the chamber is re-pressurized and more gas is added to create the next explosion — and all this is done at such a tremendous pace and with such precision that the vacuum never enters the equation except to eject the used explosion, could this different kind of engine function to propel the contraption surrounded by vacuum?


I'm not sure the concussive force inside the closed chamber would help because the wall pushes back with the same force via Newton's 3rd law.

So the energy generated by combustion inside the closed chamber would partially be absorbed by the ship and the rest would be (quickly) later let into the vacuum of space where it does no work.

If the ship were floating in water or sitting on ice it would move because the energy absorbed would be transferred to the water or the ice via the hull and the ship would vibrate, rock, etc.... Vibrating a ship in the vacuum of space is not going to get you moving.
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby hoi.polloi on May 26th, 2013, 3:56 pm

Would it help if the explosion were closer to the "front" of the ship's chamber, so that it first reached the wall in the direction the ship wants to go, and then before it can reach the far wall that would result in a net-neutral counter-force knocking the ship back, the vacuum is "let in" - thereby interrupting the explosion and preserving only the initial effect of the explosion impacting the "front" of the chamber but not the "back"?
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby beyondafringe on May 26th, 2013, 4:59 pm

lux wrote:
Boethius wrote:For instance if you open a balloon at sea level the air seeps out slowly, based on pressure difference. If you want to empty the balloon faster you exert a force, press on the balloon and the air comes out faster. If you try to same experiment inside a vacuum you cannot press on the balloon to make the air come out faster, the air goes flying out of the balloon without any force, because the nature of the vacuum has already done all the work, for free, trying to equalize the pressure inside the vacuum with that inside the balloon.



This should be easy to prove with a vacuum chamber and an air-filled balloon remotely released within it.

Can you cite an example of such a proof being performed and offer some evidence of its legitimacy?



Interesting you say this as I recently found myself conversing (I.R.L.!) about early cathode rays, or electron beam technology, with a person who claimed to work on their development in the 50's or 60's, (Raytheon, if I recall) and saw demonstrations where huge steel blocks were cut instantly. Then, they re-welded them, perfectly and invisibly - all in-situ!
I am sure the flaw in this demonstrative method is obvious....

In order to show anything was happening at all, in the 'vacuum' (imperfect, as of course even if the effort to create an 'absolute vacuum' were made, it would cease to be so when, well, anything at all, were introduced to it) which was required for the 'ray beam' to function, it was claimed to me that a balloon (inflated) was placed on the far side of this (6 inch I think) cube of steel, and the popping of it observed as proof of the beam piercing the block.

I immediately dismissed any doubt about the nonsense nature of the claims, as I was sure that the gas, of whatever varieties, in the balloon, would seek to occupy the gas-vacuum and burst the balloon, pretty much instantly.

Am I wrong? I have certainly never tried it myself, but the survival of an even partially inflated balloon in a gas/imperfect vacuum seems impossible, but I am ready to learn otherwise.
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby Boethius on May 26th, 2013, 7:46 pm

hoi.polloi wrote:Would it help if the explosion were closer to the "front" of the ship's chamber, so that it first reached the wall in the direction the ship wants to go, and then before it can reach the far wall that would result in a net-neutral counter-force knocking the ship back, the vacuum is "let in" - thereby interrupting the explosion and preserving only the initial effect of the explosion impacting the "front" of the chamber but not the "back"?


I don't think so.

This feels a lot like trying to push the rocket from inside the rocket. Lets say a pressure imbalance occurs against only one wall. There will be a force generated but that energy goes into the hull of the ship where is it turns into vibration, heat, etc... there is nowhere for the energy of the hull to go because the ship is a closed system, insulated by the vacuum of space.

There are "how does a rocket work" sites that realize this closed system problem and use the nozzle / escaping gasses as a way to "open" the system. However this is an error because free expansion means that no work, energy or heat is transferred out via the escaping gasses and the system remains closed just spread out over a larger distance. Think of it like money. If I have $1 it doesn't matter if I break it into nickels, dimes, pennies my net worth only changes when I spend it (or earn more). So breaking my dollar has no affect my financial status. Changing the energy of the ship from potential to kinetic won't move the ship until that energy does work.

If the spaceship were a railway car on a track, as an open system example, the force of a pressure imbalance would find its way to the wheels which would start to turn, possibly the car would only rock back and forth but at least it would move. As for a spaceship I don't believe any motion would occur. There is no way for the ship to roll, slide, rock, float (as on water), etc... the energy delivered to the hull simply has nowhere to go hence no motion.

Closed systems
http://blowers.chee.arizona.edu/201proj ... s.pg1.HTML
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby lux on May 27th, 2013, 1:42 am

Boethius wrote:
lux wrote:
Boethius wrote:For instance if you open a balloon at sea level the air seeps out slowly, based on pressure difference. If you want to empty the balloon faster you exert a force, press on the balloon and the air comes out faster. If you try to same experiment inside a vacuum you cannot press on the balloon to make the air come out faster, the air goes flying out of the balloon without any force, because the nature of the vacuum has already done all the work, for free, trying to equalize the pressure inside the vacuum with that inside the balloon.



This should be easy to prove with a vacuum chamber and an air-filled balloon remotely released within it.

Can you cite an example of such a proof being performed and offer some evidence of its legitimacy?


If I only had a vacuum chamber....
The principle of free expansion is justified theoretically and proven experimentally. I have left many links in my posts describing both.


Yes, you left many links describing both but I didn't ask you for a description. I asked you for evidence of experimental data and the only link you've given which purports to be about an experimental proof is this one ...
http://demonstrations.wolfram.com/JouleExperimentOnFreeExpansion/
... but it's just an animation of a purported experiment and it doesn't even give the results.

Did you understand the point about the false analogy of all of these "I throw this or that and off I go" rocket thrust demonstrations?


I understood that you said it was a false analogy but, as far as I can see, you have thus far not given any logical reason to believe that it is false.
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby lux on May 27th, 2013, 1:46 am

Boethius wrote:This feels a lot like trying to push the rocket from inside the rocket.

What is wrong with that? I've pushed cars from inside cars. I've also done the same with boats, bicycles, roller skates, furniture dollies and shopping carts.

It worked fine.
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby Boethius on May 27th, 2013, 10:34 am

lux wrote:
Boethius wrote:This feels a lot like trying to push the rocket from inside the rocket.

What is wrong with that? I've pushed cars from inside cars. I've also done the same with boats, bicycles, roller skates, furniture dollies and shopping carts.

It worked fine.


Lux, of course you have pushed from within a car but that has nothing to do with how rockets theoretically can move through space.

When you push from within a car some of the energy of the pushing goes to the wheels which start to turn. A space ship is not analogous to a wheeled vehicle. A spaceship does not move because of the physics of a curved surface (wheel) interacting with a flat surface (ground).

These analogies of spaceships to cars, boats, etc... are all over the Internet. I would say to you that attempts to connect motion in the gravitational field and atmospheric conditions of earth to those in the near-vacuum and near-zero gravity of space are tricks used to deceive and mislead.

You have to go back to the basic physics of mass, velocity, momentum, acceleration, force, energy and work and apply these to the space rocket problem to see that the NASA and other apologists are faking all of the science and fooling the public who seem pretty happy to be fooled by the way.
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby Boethius on May 27th, 2013, 11:54 am

lux wrote:Yes, you left many links describing both but I didn't ask you for a description. I asked you for evidence of experimental data and the only link you've given which purports to be about an experimental proof is this one ...
http://demonstrations.wolfram.com/JouleExperimentOnFreeExpansion/
... but it's just an animation of a purported experiment and it doesn't even give the results.


Here is an article from the Journal of Physical Chemistry with experimental results on Free Expansion
http://pubs.acs.org/doi/pdf/10.1021/j150043a002


Boethius wrote:Did you understand the point about the false analogy of all of these "I throw this or that and off I go" rocket thrust demonstrations?


lux wrote:I understood that you said it was a false analogy but, as far as I can see, you have thus far not given any logical reason to believe that it is false.


None of the analogies I have seen take into account that on earth physics operates within a gravitational field and inside an atmosphere. I consider "space" to be a near-vacuum with almost zero gravity. These analogies always involve vehicles physically connected to and interacting with the environment (planes->air, boats->water, cars->ground, etc...) whereas a rocket in space is isolated. Forces are not transferred between the vacuum and the ship in either direction. The vacuum does not affect the ship nor the ship the vacuum.
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby lux on May 27th, 2013, 12:50 pm

Boethius, as far as I can see your argument boils down to "a rocket within the atmosphere only moves because its exhaust pushes against the air behind it and in space there is no air to push against so it won't move."

The fallacy here is that that is not why rockets move so the argument makes no sense.

I also don't wish to pursue this pointless, circular debate any further.
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Re: Why Rocketry Doesn't Work in the Vacuum

Postby Boethius on May 27th, 2013, 1:02 pm

lux wrote:Boethius, as far as I can see your argument boils down to "a rocket within the atmosphere only moves because its exhaust pushes against the air behind it and in space there is no air to push against so it won't move."

The fallacy here is that that is not why rockets move so the argument makes no sense.

I also don't wish to pursue this pointless, circular debate any further.


If I didn't know any better I would say that you haven't read any of my posts.

I have not postulated a single reason for why rockets move in space. Instead I have spent my time exploring why the NASA theory, equation and explanation goes against the principles of Newtonian physics (2nd and 3rd laws of motion).

What is your explanation for why rockets move in space? Do you agree with the NASA equation? What, exactly, is your position?
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