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.
lux
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by lux »

Disclaimer:
Well, I shouldn't have started this because, as I've said, there's really nothing conclusive in these videos. It's also not a major point of mine but videos apparently attract more attention than logic does, I guess. I only meant to point out that I see no indication of support for the free expansion claims of "no work being done." But, it's not proof one way or the other and I'm not asserting it as proof of anything.

So, with that in mind -- in this one, beginning at 1:40 ...


full link: http://www.youtube.com/watch?v=U1kEf5nh-TA

... when the yellow balloon bursts it knocks about the other balloon with visible force. How could it do this if "no work was being done"? Shouldn't it simply deflate?

You can also see that the yellow balloon bursts exactly as it would do in normal atmosphere -- the burst looks exactly the same as the popping of a balloon normally would.
Last edited by lux on Thu May 30, 2013 3:46 pm, edited 2 times in total.
lux
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by lux »

hoi.polloi wrote:
Hold on. Wait a minute, stop the presses. Isn't the balloon's air pushing against the ground and walls of the vacuum chamber? Woops, back to the drawing board, I guess?
Pushing that results in movement is work (reference). How can there be work done if "no work is done when gas is released in a vacuum" as we have heard on this thread ad nauseum?

But, it's a moot point in that first balloon video I posted because the balloons are only moving due to the operator releasing the vacuum seal on the jar. You can see him throw the release just before the balloons begin to move.

However, you can see movement in the video above when the yellow balloon bursts. Work IS being done.
lux
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by lux »

hoi.polloi wrote:No prob, lux.

My sense is the nozzle of the balloon should be facing the inside of a much larger chamber if we are going to properly simulate even a micro rocket in space, I would presume. Since solids can be separated by the motion of the gas, there should be no solid in front of the nozzle of the balloon, to give us a better understanding of what could happen in empty space. Or am I misunderstanding the 'free expansion' argument?
Yes, I agree. That's why I say these videos are not conclusive.

A large vacuum chamber, say the size of a room, where someone remotely launches a small rocket would be much better.

Such a demonstration, if the rocket couldn't fly, would be monumental in its implications but for some reason no such demo can be found. I think it's because such a rocket would fly.
lux
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by lux »

OK, I'm going to take a vacation from this thread for a while [sounds of thundering cheers from the grandstands] and let you all discuss this without my rude interjections.

As I've said, I agree that NASA probably can't use rockets in space in any real practical way but I don't think this thread covers the reason for that. I think it has more to do with things such as liquid fuel management problems (which plagued Goddard and the Nazis) and gravity/weight/thrust issues and possibly radiation too. Maybe they can launch a solid fuel rocket into space but they couldn't vary its thrust once it was out there so it would have little or no practical value.
Last edited by lux on Thu May 30, 2013 5:30 pm, edited 2 times in total.
Farcevalue
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Farcevalue »

Just curious: How do we know that "space" is a vacuum?
Boethius
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Boethius »

Maat wrote:Hi Boethius,

I've really enjoyed reading your articulate arguments on this subject as well as the challenges and discussions it has inspired. I also understand Lux's frustration with not having something to show that could demonstrate the evidence for it, though.
Hello Maat,

thanks for the pleasant comments about my posts :)

I understand that not having video or photographic evidence to support a thesis is not the norm on Cluesforum.

There is not much I can do about this. One issue is that there are no zero-gravity vacuums here on earth so it will be difficult to find an experiment that replicates the conditions in space. Also, you are not going to find scientists openly challenging NASA. Science, as you may have noticed, is a toe-the-line endeavor. Anyone who goes against accepted science is called a kook, denied funding and ostracized. The idea of a "maverick scientist challenging the status quo" is a fiction.

As such I have to build my case from scattered pieces of science and theory. This kind of investigation is always difficult for others to follow along. Thanks for sticking with me. I am happy, as always to answer any and all questions.
Maat wrote: I'm curious if it would be possible to do so by using the balloon in a bell jar vacuum idea. When sealed it apparently expands like this:


full link: http://www.youtube.com/watch?v=DcnuQoEy6wA

but, if the balloon opening could be clamped (not tied) to seal it and then unclamped inside the vacuum to release the air — by your theory it should simply equalize the pressure (by free expansion) without actually being propelled in any direction as it would in normal atmosphere. Is that right?
Based on what I've read about gas exposed to a vacuum, the balloon should deflate without flapping around. I've been looking around online to see if I can find any examples of this and so far no luck.

I doubt I'll find one. The vacuum chamber used in such an experiment would have to be many, many times wider than the balloon so that the air could completely exit the balloon without degrading the vacuum. One of the table-top models they use to blow up balloons wouldn't work.
Boethius wrote:
Why would NASA claim to be able to send rockets into space when the USAF couldn't get the same technology into even the upper atmosphere?

Why did Chuck Yeager not join the space program? Did he know it was a hoax?
Maat wrote: Incongruity is often a compelling clue worth investigating :)
My feeling is that NASA didn't want or need pilots and Chuck never wanted to be anything but a pilot, but, hey, that's just my feeling.
Last edited by Boethius on Fri May 31, 2013 1:13 am, edited 1 time in total.
Boethius
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Boethius »

lux wrote:Disclaimer:
Well, I shouldn't have started this because, as I've said, there's really nothing conclusive in these videos. It's also not a major point of mine but videos apparently attract more attention than logic does, I guess. I only meant to point out that I see no indication of support for the free expansion claims of "no work being done." But, it's not proof one way or the other and I'm not asserting it as proof of anything.

So, with that in mind -- in this one, beginning at 1:40 ...


full link: http://www.youtube.com/watch?v=U1kEf5nh-TA

... when the yellow balloon bursts it knocks about the other balloon with visible force. How could it do this if "no work was being done"? Shouldn't it simply deflate?
When the yellow balloon bursts two things happen
1. The tube ceases to be a vacuum because it is now (instantly) filled with air from the burst balloon.
2. The plastic from the burst balloon flies about because that's what happens when you stretch and release plastic

both of these effects are involved in knocking about the other balloon
lux wrote: You can also see that the yellow balloon bursts exactly as it would do in normal atmosphere -- the burst looks exactly the same as the popping of a balloon normally would.
I don't think being in vacuum has any influence on what happens to the plastic of a balloon when it is popped. Plastic is a solid which behaves the same in a vacuum or in normal atmosphere. Regardless of what the air inside the balloon does or does not do the plastic skin has to resolve the problem of lost tension.
hoi.polloi
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by hoi.polloi »

Farcevalue wrote:Just curious: How do we know that "space" is a vacuum?
I agree with this question.

However, we are only testing NASA's claims that it is.
pov603
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by pov603 »

If one of the astro-nots on the 'ISS it or ISSn't it' released a ball of water [that they seem so fond of doing in such a pristine environment where water let loose obviously wouldn't interfere with the electrical items on board...] and then changed the atmospheric pressure to change the state of the globule of water, surely it would expand into nothingness [so to speak] because it wouldn't have the jar or gravity to contend with/contain/support?
We would then see [almost] free expansion at work [no pun intended :-)]?
Boethius
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Boethius »

pov603 wrote:If one of the astro-nots on the 'ISS it or ISSn't it' released a ball of water [that they seem so fond of doing in such a pristine environment where water let loose obviously wouldn't interfere with the electrical items on board...] and then changed the atmospheric pressure to change the state of the globule of water, surely it would expand into nothingness [so to speak] because it wouldn't have the jar or gravity to contend with/contain/support?
We would then see [almost] free expansion at work [no pun intended :-)]?
They would only get to free expansion, I believe, if they lowered the pressure to the level of a vacuum, but then all the astronauts would be dead unless they were wearing pressure suits.

I agree it's strange that they do these zero-gravity demos with water and other substances that you probably wouldn't want to expose to a billion dollars worth of equipment.
Boethius
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Boethius »

hoi.polloi wrote:
Farcevalue wrote:Just curious: How do we know that "space" is a vacuum?
I agree with this question.

However, we are only testing NASA's claims that it is.
Hey Farcevalue,

I've been thinking about this question as well.

If space is a vacuum what does this mean for the Theory of Relativity which makes a lot of noise about "the fabric of spacetime"? How can a fabric be spun out of nothing (the contents of a vacuum)? How can space bend, to create the effect of gravity for instance, if space is a vacuum devoid of matter? You can't bend nothing.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Heiwa »

Boethius wrote:
If space is a vacuum what does this mean for the Theory of Relativity which makes a lot of noise about "the fabric of spacetime"? How can a fabric be spun out of nothing (the contents of a vacuum)? How can space bend, to create the effect of gravity for instance, if space is a vacuum devoid of matter? You can't bend nothing.
Vacuum is just some sort of emptiness on Earth, e.g. a completely empty compartment full of nothing ... except small, small particles. Space, e.g. the environment outside Earth is also some sort of emptiness with nothing in it except those small, small particles that do not count as they have no mass; gravitons, photons, etc., which are flying around to tell us that the Sun shines and keeps the Moon in place orbiting Earth. If a graviton or photon can occupy vacuum, I am certain that simple Earth rocketry works in the Vacuum! :D :P :lol: :rolleyes:
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by brianv »

Heiwa wrote:
Boethius wrote:
If space is a vacuum what does this mean for the Theory of Relativity which makes a lot of noise about "the fabric of spacetime"? How can a fabric be spun out of nothing (the contents of a vacuum)? How can space bend, to create the effect of gravity for instance, if space is a vacuum devoid of matter? You can't bend nothing.
Vacuum is just some sort of emptiness on Earth, e.g. a completely empty compartment full of nothing ... except small, small particles. Space, e.g. the environment outside Earth is also some sort of emptiness with nothing in it except those small, small particles that do not count as they have no mass; gravitons, photons, etc., which are flying around to tell us that the Sun shines and keeps the Moon in place orbiting Earth. If a graviton or photon can occupy vacuum, I am certain that simple Earth rocketry works in the Vacuum! :D :P :lol: :rolleyes:
Your over-use of smilies is quite annoying and doesn't help your assumptions.

We are talking about Space here not a vacuum. Do particles traveling at light speed observe the same laws of physics?
It's slightly out of my league but I have tried wrapping my head around the idea that Space is an abstraction. The product of our collective Newtonian brains.

newtonian brain

Would rockets work in an abstraction?

https://en.wikipedia.org/wiki/Abstraction
Abstract things are sometimes defined as those things that do not exist in reality or exist only as sensory experiences, like the color red.
Space is just a sensory experience! That's exactly what I mean!
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by pov603 »

Isn't the term 'space' merely a construct to help us pigeonhole our understanding of it?
For example two oranges together can be referred to as 'oranges' however, how far apart do they need to be before you refer to them as 'an orange there and another orange there' rather than oranges?
In the same way that molecules/atoms apart or one per cubm suddenly cease to be a solid, liquid, gas and become space?
Boethius
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Boethius »

Goddard's flawed test of the theory of rockets in a vacuum.

Physicist Robert Goddard (for whom the Goddard Space Center is named) was one of the first to claim that rockets would work in the vacuum of space.

The New York times mocked his ideas in a 1920 editorial.
http://en.wikisource.org/wiki/The_New_Y ... rt_Goddard

In response Goddard set up the following experiment to prove the NYT wrong:

Inside a vacuum tube he attached a .22 caliber revolver, loaded with a blank cartridge, to a rod that turns .
There is no film of the experiment but first hand reports claim that when he fired the gun it spun around four times. Thus Goddard declared his theory experimentally proven.
http://www.clarku.edu/research/archives/goddard/faq.cfm

I claim that his experiment was not a test of rocket thrust in a vacuum for the following reasons:

1. A blank cartridge expels a plug of paper called a wad. The wad is expelled with enough force to kill a person. If a gun propels an object conservation of momentum applies and the gun will recoil. Rockets in space do not shoot bullets, wads or any such solids. They only expel gas.
http://en.wikipedia.org/wiki/Blank_%28cartridge%29
http://io9.com/5972313/why-a-gun-loaded ... l-kill-you

2. The gun was attached to a rod which was attached to the top (or side) of the vacuum tube. This is not state of a rocket in space which is totally insulated from any other object. Because the gun is attached to a rod it is not a closed system. The gun pushes against the rod (exchanges energy) when fired. In a proper setup the gun would be suspended in zero-gravity or some simulation thereof.

3. Even if he had arranged to fire a gun without expelling a wad, even if he had managed to simulate a gun in zero gravity and not used one attached to a rod, he still had the issue that gas fired from the gun was interacting with the sides of his vacuum tube. If gas fired from the gun pressed against the sides it would create turbulence which means that the gasses leaving to gun barrel wouldn't have a chance to experience free expansion. Space doesn't have "sides" that gas bounces off of. Every molecule goes flying off into the void without interacting with any other. Another way to think about this is that once the area in front of the gun muzzle is no longer a vacuum, free expansion stops.

(The loop at the bottom is so that it doesn't bounce off the bottom but what about preventing the gas from interacting with the sides?)

Goddard's experiment is critically flawed and cannot be used as evidence that a rocket will work in a vacuum yet it was used as the basis for continued funding, research and belief in space rockets.

Goddard's Vacuum Tube
Image
(source http://commons.wikimedia.org/wiki/File: ... 001338.jpg)
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