Does Rocketry Work in the Vacuum?

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Does Rocketry Work in the Vacuum?

Postby Boethius on May 25th, 2013, 2:21 pm

[ADMIN: This topic was started due to our recent discussions — in multiple threads — about the subject of rocketry.

Specifically, there seems to be a growing skeptical understanding of the science of rocketry and just what is wrong with it, and why it doesn't work in the manner NASA says it does. (i.e.; bad physics used to back up their special effects publicity stunts like Apollo, "Mars missions", etc.)

In memory and honor of Bill Kaysing (or perhaps we'd better just say in honor of good sense) let's present the science here that shames the Wernher von Brauns of our world into coughing up the truth: their rocket programs are full of hot air. - hp]



I'm not sure if this is the right place for this post. feel free to move/edit as necessary.

After seeing the evidence of fakery in NASA pictures and videos in this forum I decided to investigate the theoretical basis of rockets in space. What I found on the Internet were mainly tricks, frauds and sleights of hand, name-calling and attacks used to confuse the issue and hide the facts. Bypassing all of that and doing original research I have come to the conclusion that rockets cannot function in space according the descriptions/formulas used by NASA and related parties.

With neither theory on its side nor reliable, verifiable, repeatable scientific experiments on its side the idea of rocket thrust in my estimation remains a fiction presented to the world as an achievement: a modern day Marco Polo story.

I will try to present my findings with a minimum of math and formulae as these are often used to drawn us into traps, causing us to argue the minutiae of red herrings or chase ghosts. These ruses remind me of the joke about on which side of the barn roof the rooster’s egg will fall. How often do people forget that rooster’s don’t lay eggs?

There are 4 major ideas on presented on the Internet, including NASA web sites, as to how rockets generate thrust in space
1. Newton’s 3rd Law : for every force there is an equal and opposite
2. Newtons’s 2nd Law : Force = Mass x Acceleration
3. Conservation of Momentum
4. The use of a specialized nozzle to accelerate the gas inside the ship, concentrate and aim the gas jet

I will address each of these issues showing why they are invalid. In addition I will review the results (and lack thereof) of the founders of space rocketry Obereth (who designed most of the rocket science for the Fritz Lang film Woman in the Moon), Goddard, who was the first to claim an experimental result proving vacuum thrust and Clarke, a champion of Newton’s 3rd law.

There’s obviously too much to cover in one post so I’ll start by addressing the most popular response to those who question how rockets operate in the vacuum of space: Newton’s 3rd Law, that is to say that a rocket when it exhausts propellant will be pushed in the opposite direction.

The problem with applying Newton’s 3rd is that the rocket’s propellant does not generate force in a vacuum according to the laws of physics and chemistry. If the force of the propellant is 0 then Newton’s 3rd states that
Force on Rocket=-Force of Gas.
If Force of Gas = 0 the rocket does not move.

Why doesn’t the propellant generate any force, it's expanding, right?
There is something known as “Free Expansion” or the “Joule-Thomson” effect, named after James Prescott Joule and J.J. Thompson two of the founders of the field of Physical Chemistry.
http://www.etomica.org/app/modules/site ... ound2.html
Free Expansion states that when a pressurized gas is exposed to a vacuum the gas expanding into the vacuum without any work being done. The gas is not “pulled” or “sucked” into the vacuum nor is it “pushed” out of the high-pressure container. In other words no work is done, no heat or energy is lost.
This result has been experimentally verified numerous times since its discovery in the 1850’s.
[for example a paper in the Journal of Physical Chemistry from 1902: http://pubs.acs.org/doi/pdf/10.1021/j150043a002]

As if Free Expansion wasn’t enough to invalidate the theory of rockets producing a force in a vacuum there is also a result from thermodynamics:
Work = Pressure x Change_in_Volume
that is easily found searching for “W=PV”
http://lsc.ucdavis.edu/~ahart/Alicia2B/Thermo.pdf
If the pressure of a system is 0 then the work done by the expanding gas into that system is 0. Gas expanding in a vacuum doing no work agrees with Free Expansion. This can also be understood as the gas meets no resistance as it exits into the vacuum and thus transfers neither heat nor energy to its surroundings. If the gas loses neither heat nor energy then it has done no work.

At this point we have a rocket with high-pressure gas generated from liquid fuel that can release the gas into a vacuum but has no way to produce a force while doing so. As soon as the nozzle is opened the gasses escape without doing any work. Therefore the 3rd Law is rendered useless.

As it turns out NASA does not fall into the 3rd Law trap (nor does it go around correcting all the sites who do) instead claiming that thrust of a space rocket is generated using what I call The Wrong Formula, an egregious farce of Newton's 2nd law which I will address in a later next post.

To recap: Newton’s 3rd Law, the number one response on the Internet to how a rocket generates thrust in space, is invalid in this context. NASA itself avoids using Newton’s 3rd Law as the reason why their rockets work so well in space choosing to use Newton’s 2nd Law instead. I will show in a later post why NASA’s use the 2nd Law is equally invalid and in fact a hideous misrepresentation of the laws of the laws of physics that would give a freshman college student a failing grade yet earns NASA an "A" thanks to its pretty pictures, dramatic story lines, and gutsy champions, the astronauts.
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Re: Fakery in Orbit: THE I$$

Postby hoi.polloi on May 25th, 2013, 4:20 pm

Free Expansion states that when a pressurized gas is exposed to a vacuum the gas expanding into the vacuum without any work being done. The gas is not “pulled” or “sucked” into the vacuum nor is it “pushed” out of the high-pressure container. In other words no work is done, no heat or energy is lost. This result has been experimentally verified numerous times since its discovery in the 1850’s.


Gas expanding in a vacuum doing no work agrees with Free Expansion. This can also be understood as the gas meets no resistance as it exits into the vacuum and thus transfers neither heat nor energy to its surroundings. If the gas loses neither heat nor energy then it has done no work.


I think I see what you mean. To try to put this in unnecessarily simple layman's terms: because the vacuum is just complete void, it can freely take on just about an infinite amount of anything, at any rate, without actually anything significant happening. Hence, we hold on to the idea that mass exiting a craft into a vacuum would actually cause any motion in the craft only because we are used to such behavior in a non-vacuum.

On Earth, shooting something causes friction with the thing being shot. Least of all, air all around us. The shooter will be effected by the action of shooting. However, in a vacuum, there being no friction with anything, shooting something just wastes that thing and sends it soaring uselessly into the void.

But if that's true, then you're saying a gun (by a magic gunman and gun that can exist and fire in a perfect vacuum) would not be pushed back by the bullet, it would just eject the bullet without an effect on the gun or the arm of the gunman? Simply because of a lack of air pressure and friction and so on?

So there is no jet propulsion that would work because any explosive reaction that could even occur in space would be wasted in it completely.
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Re: Fakery in Orbit: THE I$$

Postby hoi.polloi on May 25th, 2013, 4:59 pm

The reciprocal of 0 force is 0 force.

The equal and opposite reaction to 0 would be 0.

Rockets would reach their maximum height, then fall back to Earth, and - most likely - explode and burn up. None of this "orbit" nonsense so close to the Earth.
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Re: Fakery in Orbit: THE I$$

Postby Boethius on May 25th, 2013, 6:12 pm

hoi.polloi wrote:
On Earth, shooting something causes friction with the thing being shot. Least of all, air all around us. The shooter will be effected by the action of shooting. However, in a vacuum, there being no friction with anything, shooting something just wastes that thing and sends it soaring uselessly into the void.

But if that's true, then you're saying a gun (by a magic gunman and gun that can exist and fire in a perfect vacuum) would not be pushed back by the bullet, it would just eject the bullet without an effect on the gun or the arm of the gunman? Simply because of a lack of air pressure and friction and so on?

So there is no jet propulsion that would work because any explosive reaction that could even occur in space would be wasted in it completely.


Short answer: Yes a gun recoils in space. No, the analogy does not apply to rockets.

Longer version: Shooting a gun in space would happen theoretically as follows: pressurized gas accelerates the bullet through the barrel until the bullet leaves the muzzle. At that point the gas that was pushing the bullet escapes without doing any more work i.e. via free expansion. The energy of the bullet (its momentum) travels with the bullet and the gun recoils by principle of conservation of momentum.

The gun analogy does not apply to a NASA-type space rocket as their pressurized gas escapes without doing any work at all. A NASA rocket is a gun without a bullet.
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Re: Fakery in Orbit: THE I$$

Postby Boethius on May 25th, 2013, 6:35 pm

hoi.polloi wrote:
I think I see what you mean. To try to put this in unnecessarily simple layman's terms: because the vacuum is just complete void, it can freely take on just about an infinite amount of anything, at any rate, without actually anything significant happening. Hence, we hold on to the idea that mass exiting a craft into a vacuum would actually cause any motion in the craft only because we are used to such behavior in a non-vacuum.


You are correct, in addition to the gas leaving the ship for "free" (doing no work, exerting no force) the change in the mass of the rocket due to the escaped gas has nothing to do with rocket propulsion. In order for "lost mass" to exert force the ship MUST be accelerating. The formula is:

Force = Mass x Acceleration

If Acceleration is 0 then force is 0 no matter what the mass or how it is changes over time.

Put another way, if the force of the gas (force = 0) exiting the ship didn't do cause the ship to move (the ship isn't accelerating) due to free expansion then looking at the problem from the perspective of the mass of the gas leaving the ship won't magically cause the ship to move all of a sudden.

NASA tries to pull this nonsense as well as some other ridiculous fake science stunts to make it seem like their rockets have a chance to function in a vacuum.
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Postby simonshack on May 25th, 2013, 6:42 pm

Boethius wrote:
I will try to present my findings with a minimum of math and formulae as these are often used to drawn us into traps, causing us to argue the minutiae of red herrings or chase ghosts. These ruses remind me of the joke about on which side of the barn roof the rooster’s egg will fall. How often do people forget that rooster’s don’t lay eggs?


Boethius,

Thanks for bringing some well-documented common sense to debunk NASA's outlandish claims of having rockets moving in a vacuum.

A quick way of teaching kids why rockets cannot proceed in a vacuum: think of a man swimming in a pool. The man will move forwards. If this man gets out of the pool and keeps flapping his arms as if swimming, he won't move forwards, because the air simply doesn't produce enough 'thrust' (superior to the so-called forces of gravity which affect his body) to propel him forwards.

Also, anyone with a modicum of aeronautical knowledge will know what a 'stall' means, that is when an airplane loses lift and, one could say, 'encounters vacuum'. The plane will plunge catastrophically to the ground - if aerodynamic support isn't quickly re-established.

Stall
"(Engineering / Aeronautics) a condition of an aircraft in flight in which a reduction in speed or an increase in the aircraft's angle of attack causes a sudden loss of lift resulting in a downward plunge."
http://www.thefreedictionary.com/stall


A third analogy would be that of a car moving up a mountain road - and suddenly encountering a big icy patch. The car will keep spinning its wheels - but it will stop moving forward.

I believe that the impossibility of propelling a rocket out of our planet's atmosphere was discovered at an early stage of space travel experiments. Any rocket reaching a certain, critical altitude (for which I surely won't pretend to provide/ specify any exact figure) simply stalls - due to the absence of air, and plummets back into the atmosphere.
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Postby beyondafringe on May 25th, 2013, 6:59 pm

Simon,

I think an aircraft (winged) stalls when the flow of air across the lift-generating wing surface becomes insufficient to maintain said lift; to the requirements of the aircraft in question, weight most significantly I would think.

Rockets, as we know, rely on cheering technicians maintaining exuberance to the required altitude!
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Re: Do Rockets Generate Thrust in the Vacuum of Space?

Postby Boethius on May 25th, 2013, 7:04 pm

simonshack wrote:I believe that the impossibility of propelling a rocket out of our planet's atmosphere was discovered at an early stage of space travel experiments. Any rocket reaching a certain, critical altitude (for which I surely won't pretend to provide/ specify any exact figure) simply stalls - due to the absence of air, and plummets back into the atmosphere.


Yes, Simon. 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. Chuck Yeager almost died in a NF-104A rocket plane failure while attempting to set a height record. These planes were liquid fuel rockets and not air-fed jets.

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?
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Postby lux on May 25th, 2013, 10:53 pm

Boethius wrote:Short answer: Yes a gun recoils in space. No, the analogy does not apply to rockets.

Longer version: Shooting a gun in space would happen theoretically as follows: pressurized gas accelerates the bullet through the barrel until the bullet leaves the muzzle. At that point the gas that was pushing the bullet escapes without doing any more work i.e. via free expansion. The energy of the bullet (its momentum) travels with the bullet and the gun recoils by principle of conservation of momentum.

The gun analogy does not apply to a NASA-type space rocket as their pressurized gas escapes without doing any work at all. A NASA rocket is a gun without a bullet.


So, a gun without a bullet (i.e., a blank cartridge) wouldn't recoil if fired in space? I don't think so.

The expanding gasses expand in all directions. They would meet little or no resistance at the muzzle but they would meet resistance in the opposite direction and the shooter would feel that as recoil.

I don't doubt that rockets in space wouldn't work as well as NASA claims but I don't see that they wouldn't move at all.
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Postby Boethius on May 25th, 2013, 11:48 pm

lux wrote:So, a gun without a bullet (i.e., a blank cartridge) wouldn't recoil if fired in space? I don't think so.

The expanding gasses expand in all directions. They would meet little or no resistance at the muzzle but they would meet resistance in the opposite direction and the shooter would feel that as recoil.

I don't doubt that rockets in space wouldn't work as well as NASA claims but I don't see that they wouldn't move at all.


Hello lux,

when I say "a gun without a bullet" I mean a gun with an empty chamber, a gun that expels only hot gas, basically a simplified model of a rocket.

In this case "free expansion" states that the gas from the gun enters the vacuum of space without doing any work, absorbed instantaneously and without recoil. Recoil in a gun only occurs when gasses do work on a projectile, to expel it and/or on the atmosphere outside/inside of the muzzle encountered as resistance.

The principle of free expansion comes from Joule and Thompson in the 1800's and has been experimentally verified. No, I don't suppose you will hear many people discuss it around the NASA water cooler...

Free expansion is such a taboo subject at NASA that the only place I found it on their websites was tucked away under the definition of "first law of thermodynamics".

http://er.jsc.nasa.gov/seh/f.html
http://prettygoodphysics.wikispaces.com ... Vacuum.pdf
http://www.physicsforums.com/showthread.php?t=151250
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Postby lux on May 26th, 2013, 12:55 am

Boethius wrote:
Hello lux,

when I say "a gun without a bullet" I mean a gun with an empty chamber, a gun that expels only hot gas, basically a simplified model of a rocket.

In this case "free expansion" states that the gas from the gun enters the vacuum of space without doing any work, absorbed instantaneously and without recoil. Recoil in a gun only occurs when gasses do work on a projectile, to expel it and/or on the atmosphere outside/inside of the muzzle encountered as resistance.


Guns with empty chambers don't expel anything. Guns with a charge in them (with or without a projectile) can expel something.

Further, I don't understand why you say that expelling gas does no work. Gas has mass too and moving that mass is work.

And, besides that there is a force at work in the expansion of gas within the gun. A force vectored in all directions. If that force meets little or no resistance in the forward direction the result will be that the gun will move backward simply because the expanding gas pushes it that way.

Or, at least, that's the way I understand Newton's laws.

The principle of free expansion comes from Joule and Thompson in the 1800's and has been experimentally verified.


This means nothing to me. I don't know either of these guys and you'll have to do more than merely say that they proved something to convince me, sorry. Your statement above, "'free expansion' states that the gas from the gun enters the vacuum of space without doing any work ..." doesn't seem true to me as I've noted due to the fact that moving gas is doing work just as moving a solid is.

You also haven't explained thrust (as from rocket motors) and how it relates to all this.
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Postby simonshack on May 26th, 2013, 2:19 am

lux wrote:You also haven't explained thrust (as from rocket motors) and how it relates to all this.


Neither has NASA, dear Lux... for almost half a century now! ^_^
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Postby Boethius on May 26th, 2013, 2:29 am

Part 2 of why NASA’s rockets can’t work in space

NASA claims that by pressurizing gas and shooting really fast out of the back of a rocket they can create thrust in a vacuum.

Using only NASA web sites I can show that their equation for rocket thrust is bunkum.

First, the NASA rocket thrust equation (written in lay language)

Force = Mass x Velocity + (Pressure Difference between inside the rocket and the vacuum of space) x Nozzle Area

http://www.grc.nasa.gov/WWW/k-12/airplane/rockth.html

The first term says Force = Mass x Velocity whereas NASA web sites say that
Force = Mass x Acceleration (Newton’s 2nd law of motion)
NASA sites also say that Mass x Velocity = Momentum which is not a force. Momentum is potential energy. If you throw a rock it has momentum. If you throw it harder it has more momentum. No force is generated until the rock hits something. Gas shot out of the back of a rocket very fast does not create a force until it interacts with something, which it never does in the vacuum of space. It remains high momentum gas streaking endlessly through space looking to do work but never getting the chance.

The second term (Pressure Difference between inside the rocket and the vacuum of space) x Nozzle Area
violates the “free expansion” effect, part of the first law of thermodynamics by which pressurized gas moves into a vacuum without any work being done. It does not matter how highly pressured the gas is inside the rocket nor how fast it comes out. Because it is going into a vacuum the gas makes the trip “for free” and does not do any work, does not expend any energy and does not create any force or thrust.

The NASA space rocket equation has two terms the first of which is incorrect and so is the second. As Linus Pauling would say, “not even wrong”. How do rockets work in the vacuum space?

Free Expansion
http://er.jsc.nasa.gov/seh/f.html

Force = Mass x Acceleration
http://exploration.grc.nasa.gov/educati ... wtona2.htm

Momentum = Mass x Velocity
http://www.grc.nasa.gov/WWW/k-12/airplane/momntm.html
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Postby lux on May 26th, 2013, 2:46 am

Boethius wrote:The second term (Pressure Difference between inside the rocket and the vacuum of space) x Nozzle Area
violates the “free expansion” effect, part of the first law of thermodynamics by which pressurized gas moves into a vacuum without any work being done. It does not matter how highly pressured the gas is inside the rocket nor how fast it comes out. Because it is going into a vacuum the gas makes the trip “for free” and does not do any work, does not expend any energy and does not create any force or thrust.


Does the gas that is expelled from the rocket have mass or doesn't it?
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Postby lux on May 26th, 2013, 2:53 am

simonshack wrote:
lux wrote:You also haven't explained thrust (as from rocket motors) and how it relates to all this.


Neither has NASA, dear Lux... for almost half a century now! ^_^


I agree but I still see holes in Boethius' argument.
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