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.

Unread postby hoi.polloi on Sun May 26, 2013 3:21 am

We may not have all the answers but thanks to this discussion, I can at least understand where the critical discussion should exist. Thanks, everyone.

I'm moving this to a new rocketry thread since all our hot air has seemingly caused the topic to drift into free space, and I don't want it to get 'burnt up' when our attentions experience re-entry to the ISS thread. ;)
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Unread postby lux on Sun May 26, 2013 3:34 am

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?

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


[edit - removed question to hoi about title of thread]
Last edited by lux on Sun May 26, 2013 3:50 am, edited 6 times in total.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby hoi.polloi on Sun May 26, 2013 3:37 am

Good question.

Let's also try to boil down just why a properly executed fuel explosion within a craft would not be able to move the craft.

If there were a successful chemical explosion or comparable force outside the craft, and at its rear, it should propel the craft forward at least a small amount. However, if the explosion is internal — as we are led to believe — this would cause equal work in all directions and hence do nothing except stress the inside of the craft.

Only by somehow releasing a strategic percentage of the explosion to the infinitely permissive vacuum would the remainder do any work against the ship and cause it to move. But how could this be accomplished using the same rockets that are meant to propel the ship via thrust against air pressure?

Given that these "maneuvering in space" rockets are different rockets for a different purpose, safely nestled amongst the original Earth-based rockets, we are supposed to believe that the force of their internal explosions alone is moving and directing the craft in space, rather than thrust against anything as it works on Earth. So I guess we are meant to believe that NASA has found a way to transition their crafts' functions — as they ascend — from Earth physics to vacuum physics. I guess this would be a delicate process given that in the vacuum:

- conventional explosions would not be fed by adequate oxygen
- air pressure could no longer be used for lift
and
- lack of pressure outside the ship would cause extreme stress on the inside of all mechanisms with pressure

In other words, the amusing little jets of gas we see exiting the craft for 'course correction' cannot possibly be what they look like: just a gas being released into the vacuum. They must instead be representations of an internal, highly controlled and precise explosive force aimed at the inside of the craft itself, and the "jet" pictured is merely the residual energy that must escape to prevent the chamber from blasting open?

Do we have any schematics of how their "we are in the vacuum now" jets are supposed to work, and fit in/amongst the other functions of the craft?
Last edited by hoi.polloi on Sun May 26, 2013 4:08 am, edited 4 times in total.
Reason: changed topic title and new post topics
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby brianv on Sun May 26, 2013 4:22 am

If I farted in space, and then without resistance, would I hurtle forwards towards infinity ?
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby pov603 on Sun May 26, 2013 4:29 am

And beyond apparently.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby brianv on Sun May 26, 2013 4:48 am

pov603 wrote:And beyond apparently.


Six pints of Guinness and a Curry look out Andromeda!
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby beyondafringe on Sun May 26, 2013 5:37 am

Can the nature of space, and therefore the behaviour of any device or machine placed into it, be anything other than speculative?

Even fundamentalist establishment science believers recently saw their 'void' or 'imperfect vacuum' crammed full of the Matter known only as Dark?

I do not recall this addition being factored in to any of the pre-DM space travelling calculations. I would contest the invention of this DM, along with it's equally Dark Energy, are like Black Holes: A purely mathematical invention, to explain the latest failure of the (certainly ambitious) fiercely defended numbers-model that explains the mechanics of the entire universe.

I see the Orion 'huge pile of nooks' alternative propulsion method gets a mention elsewhere, but I think that was a fairly early (50's/60's) lunatic notion. At the risk of divergence, I would like to draw attention to this rocket-alternative that is so crazy, so mad and sad at the same time; that it comes from the NASA of only 20 years ago makes it more or less insane, I do not know......

Image

Conceptual diagram of a Medusa propulsion spacecraft, showing: (A) the payload capsule, (B) the winch mechanism, (C) the main tether cable, (D) riser tethers, and (E) the parachute mechanism

(I found myself in a vortex of gleeful disbelief, is this going where I think it is, I thought.)

A Medusa spacecraft would deploy a large sail ahead of it, attached by cables, and then launch nuclear explosives forward to detonate between itself and its sail. The sail would be accelerated by the impulse, and the spacecraft would follow.

Image
Operating sequence of the Medusa propulsion system. This diagram shows the operating sequence of a Medusa propulsion spacecraft (1) Starting at moment of bomb / pulse unit firing, (2) As the bomb's explosion pulse reaches the parachute canopy, (3) Pushes the canopy, accelerating it away from the bomb explosion as the spacecraft plays out the main tether with the winch, braking as it extends, starting to accelerate the spacecraft, (4) And finally winches the tether back in.

http://en.wikipedia.org/wiki/Nuclear_pulse_propulsion

Yes, a 1990's cosmic sail ship, powered by nooks.

And as for Orion, and much else asylum humour;

"With a mass of 1000-2000 metric tons and 1000 nuclear bombs for propulsion the medium version alone would have been a terrifying monster. The "super" Orion design at 8 million tons could easily be the size of a small city. Here is a size comparison of some of the proposed versions:"

http://www.darkroastedblend.com/2008/10 ... -bomb.html

"As a side note, we should also mention project "Aldebaran" (1962) - immense nuclear-pulse sea-launch vehicle:"

Many hilarious projects to be found at this link, if not seen before.




Please shift off to general space spastic thread if I digressed too far. My point really was, that no reliable data exists for the nature of whatever is to be found, at a sufficient height from the ground, that it can be considered 'space'.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby Boethius on Sun May 26, 2013 11:21 am

There is also a philosophical reason why NASA space rocketry is impossible: gas, via rocket engine exhaust or otherwise, has no effect, does no work, in a vacuum and cannot be used to move objects through space (yes, that includes farts).

In 1852 scientist James Prescott Joule, for whom the unit of energy Joule is named, discovered that gas does no work in a vacuum http://www.etomica.org/app/modules/site ... ound2.html

If gas has an effect on objects in a vacuum I would expect to find an example in nature. All forces that man has access to exist in nature (including fission, fusion, chemical reactions, steam, etc...). We do not create forces we only discover them. In ancient times people thought a comet's tail was a gas jet pushing it along. Today I cannot find an example of an object moving through space via gas/jet propulsion although streams of gas and particles shooting into space exist. Saturn's moon Enceladus, for example, shoots a jet of water ice 500 KM into space. The diameter of the moon itself is only 500 KM. Does this jet have any effect? No. The jet as tall as the moon is wide goes harmlessly off into space. http://en.wikipedia.org/wiki/Enceladus_%28moon%29

Gas does no work in a vacuum. It is only a passive participant and not an active force in space. We cannot use it as the basis for space travel. Bottling up gas and shooting it out of a tiny nozzle won't change its basic physical properties inside a vacuum, won't suddenly invalidate the laws of thermodynamics.

The theory of space travel based on gas jets and/or liquid propellants is a science fiction from the 1800's (Jules Verne et. al.) similar to the philosopher's stone and other magical, mystical pursuits we now look down upon. I have already addressed NASA's phony rocket thrust equations (and will continue to do so as necessary). There is also the matter of the faked/fraudulent results of rocket pioneers such as Goddard which I will get to later.

If you ask why this is hoax is still going on it is because science has become a religion and NASA it's church. Specifically space travel is one of the Holiest of Holies. Try debunking a religion/cult and see how far you get. Once someone has been indoctrinated, invested themselves in its beliefs, it is nearly impossible for them to divest. For years I believed that space travel was the pinnacle of man's achievement. Now I have to wonder if any rocket has ever been past as far as we can throw it up from the ground.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby lux on Sun May 26, 2013 11:52 am

Boethius wrote:There is also a philosophical reason why NASA space rocketry is impossible: gas, via rocket engine exhaust or otherwise, has no effect, does no work, in a vacuum and cannot be used to move objects through space


... except that gas does have mass and moving it does therefore accomplish work.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby hoi.polloi on Sun May 26, 2013 12:11 pm

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

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?

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?

Thank you for addressing these questions, before continuing your passages.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby CitronBleu on Sun May 26, 2013 12:36 pm

Boethius wrote:Gas does no work in a vacuum. It is only a passive participant and not an active force in space. We cannot use it as the basis for space travel. Bottling up gas and shooting it out of a tiny nozzle won't change its basic physical properties inside a vacuum, won't suddenly invalidate the laws of thermodynamics.


I remember reading this was one of the first arguments meant to debunk space travel back in the 1940s, some journalists mentioning it as reason for the impossibility of movement in a vacuum.

However then how do we make sense of a jet plane traveling in the sky? The jet plane does not move because the jet expelled from its thrusters "compresses" the air behind it, but because one force is acting against another. The explosive "jet" pushes the object from which it is emanating.

To claim an object in space cannot move because it produces a jet in a vacuum is to claim it cannot move because there is nothing to "compress" against. But that is not how the forces of momentum function!
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby lux on Sun May 26, 2013 12:47 pm

... and if a man stands on a small untethered boat and throws a heavy rock off the stern, the boat will move forward. It's not because the weight "pushed against the air" behind it but because the man pushed against the rock in a particular direction.

I wonder why BOeThius doesn't respond to questions put to him?
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby Boethius on Sun May 26, 2013 12:50 pm

lux wrote:
Boethius wrote:There is also a philosophical reason why NASA space rocketry is impossible: gas, via rocket engine exhaust or otherwise, has no effect, does no work, in a vacuum and cannot be used to move objects through space


... except that gas does have mass and moving it does therefore accomplish work.


Moving gas into a vacuum, such as from inside a rocket in space to outside, is not a process that requires work. This is because free expansion allows enters a vacuum "for free", no work is needed or done. The gas does not push outward from inside the rocket and is not pulled in by the vacuum of space. Natures seeks to being the two sides, high pressure and zero pressure, into equilibrium and does so for "no charge". Although this is a well-known result in Physical Chemistry and Thermodynamics you almost never hear of it in the context of space rocketry because it wreaks havoc on the NASA-led theories of thrust.

I have noted free expansion several times and produced various web sites describing it. Do you not believe that it exists? It can be and has been tested in vacuum chambers here on earth. I have yet to see a convincing experiment describing how rockets produce thrust inside a vacuum performed on earth. All the testing seems to be done up there in space.

Free Expansion
http://www.etomica.org/app/modules/site ... ound2.html
http://demonstrations.wolfram.com/Joule ... Expansion/

Also, just because a mass is moving does not mean it does any work. Mass in motion has the property of momentum which is not the same as force. In order for momentum to be turned into force it must interact with something. A mass of gas moving at any speed through the infinite vastness of space never encountering any other object, never speeding up or slowing down does not exert any energy, does not do any work and thus cannot be used to propel anything.

Converting Momentum into Force
http://www.physlink.com/education/askexperts/ae462.cfm
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby hoi.polloi on Sun May 26, 2013 1:00 pm

Moving gas into a vacuum, such as from inside a rocket in space to outside, is not a process that requires work. This is because free expansion allows enters a vacuum "for free", no work is needed or done. The gas does not push outward from inside the rocket and is not pulled in by the vacuum of space. Natures seeks to being the two sides, high pressure and zero pressure, into equilibrium and does so for "no charge". Although this is a well-known result in Physical Chemistry and Thermodynamics you almost never hear of it in the context of space rocketry because it wreaks havoc on the NASA-led theories of thrust.


But we're not merely talking about gas being released, we're talking about the release of a chemical explosion of highly pressurized gas. The explosion causes the gas to collide with the interior of the engine, propelling it — and the attached ship — forward. Is there not a difference between releasing gas and directing an exploding fuel which does collide with the ship itself?

And how could you address the difference between thrust in vacuum compared to a jet engine operating in extremely high altitudes where there is almost a vacuum?
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby Boethius on Sun May 26, 2013 1:06 pm

lux wrote:... and if a man stands on a small untethered boat and throws a heavy rock off the stern, the boat will move forward. It's not because the weight "pushed against the air" behind it but because the man pushed against the rock in a particular direction.

I wonder why BOeThius doesn't respond to questions put to him?


Hello, Lux. I am happy to respond to your questions.

the "I throw something forward and thus I move backwards" example is one that is often used to "explain" rocket thrust. It is a false analogy.

Gas isn't being thrown from the rocket. Gas isn't propelled into space. Gas can only be propelled into an atmosphere where it encounters resistance to its flow. If there is no resistance gas flows out into the vacuum without being "thrown". This is the result known as free expansion.

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.

When high pressure gas enters a vacuum there is not even heat generated from molecules bouncing off each other trying to leave the high pressure area. The entire evacuation happens for free. No heat. No work. No muss. No mess.
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