[AATW]

They would be affected if they went through the radiation belt. This Nature article doesn't prove they were affected by radiation. All it shows is that out of 7 astronauts who supposedly went to the moon, 3 died of cardiovascular disease, not that this was due to radiation exposure.
A sample of 7 is not statistically significant. If you pick a random group of 7 US inhabitants who died between ages 55-64, often 3 of them will have died of cardiovascular disease.

I agree it's a small sample set but they seem to have had a higher than average rate of heart disease, whether it's because of this is unclear
I'm not sure they had the ability to send a monkey through the belts and return it alive to study it.
And the effects of radiation are not generally immediately apparent.
My understanding is that they did have some shielding and they chose a trajectory which attempted to minimise the exposure.
The amount of radiation the Apollo astronauts were exposed to was being monitored. Had it been a lethal dose I wonder whether they would have carried out subsequent missions but Apollo 8 went to the moon and back so I guess those guys were the guinea pigs in that regard.
These guys knew there were risks attached to these missions

Given that this is the LEM’s ascent engine tested on Earth (video @ 1:26:36), why is there no visible flame under it when it takes off from the moon?

I imagine the fact that one is operating in an atmosphere and the other in a vacuum is a factor here. If you check out the video, you can clearly see the effects of the engine starting as stuff is blown by the rocket. But if it was all special effects wouldn't they have added a flame if one "should" be there?

Given that, as confirmed by the debunkers, “the astronauts are literally sitting on the engine”, why don’t we hear any sounds from the engine during lift-off?

Because the rocket is operating in a vacuum. There may have been a bit of vibration but otherwise if there's no air to pass the sound through you're not going to hear anything. Don't forget the rocket was designed to fire on the moon so only had to lift a 6th of the weight you'd get on earth of a relatively small craft - compared to the Saturn V rockets.

Michael Collins was never on the surface of the moon, as the official story goes he remained in lunar orbit while Armstrong and Aldrin descended in the LEM.

Correct, and the question about seeing stars was to Armstrong, he confirmed he couldn't see stars from the surface any more than we can see stars in the day time on earth. Collins does then add something about not being able to see any but it's unclear what he means here, as you say, he wasn't on the lunar surface. Possibly he meant that when he was on the day side of the moon as he orbited he couldn't see any stars.

Tracking the craft up to what point?

All the way to the surface

https://www.jodrellbank.net/20-july-1969-lovell-telescope-tracked-eagle-lander-onto-surface-moon/

You can bet the Russians were tracking them too, they've never called the US out on the lie.
And at least 2 craft have been able to take good enough quality photos that we can see the Apollo landing sites, one of those being from China. Why are they verifying the US landed on the moon?

[iCare]

Let's repost the claptrap source and see what it defines as being isentropic at the nozzle:

""Isentropic flows occur when the change in flow variables is small and gradual, such as the ideal flow through the nozzle shown above. The generation of sound waves is an isentropic process. A supersonic flow that is turned while the flow area increases is also isentropic. We call this an isentropic expansion because of the area increase."

The paragraph you quote is not a "definition of what is isentropic at the nozzle"; it is only elaborating on what (some) isentropic flows are.
If you follow the embedded link in "the generation of sound waves is an isentropic process.", it explains the isentropic nature of sound waves in more detail.

Now, knowing that gas released to the confines of a vacuum does 0 work, and knowing the entirety of the nozzle (both the outside of the bell and the inside of the bell) are exposed to vacuum, neither of the conditions for "isentropic process, " are met.

The gas is not released, it is expelled. => "does 0 work" does not apply.
Once the rocket is operating, the inside of the "bell" will be filled with gas. => no vacuum. Even after leaving the bell there will not (immediately) be exposed to vacuum as the dispersing exhaust is still there.
And even if it were exposed to vacuum, it would still be an isentropic flow, because a gas flow is forced through a nozzle - for it to be isentropic it doesn't matter where it is forced "into".
It does, however, matter if it is forced (increasing amount and temperature of gas) or expanding freely (constant amount and temperature of gas). When being expelled, it is not expanding freely.
Requirements for isentropic flow are met, requirements for free expansion are not met.

All relevant factors are (in essence) the same ... so where does the force (that obviously is at work in an atmosphere) disappear to?

It disappears when gas is released into a vacuum.

Force doesn't just "disappear". Where does it go to?

Essentially what you guys are writing is that Joule's Law is wrong and that gas when released to a vacuum can do work.

No.
I have repeatedly and explicitly written, that I do not doubt Joule's Law.
The problem is, that you keep applying it to a situation it does not apply to (see above and below).

You can call it final as often as you want, that is not what Joules proved.
If there is no resistance, gas does not need to be forced; it does not mean it cannot be forced.
If you let go of a ball, you don't need to push it to fall down; that doesn't mean you can't still throw it down.
With a rocket engine there is resistance by the simple fact of the nozzle restricting the flow of gas created by the chemical reaction. There is a force. This is not (in conflict) with Joule's law of Free Expansion.

iC

[totallackey]

BR, ICare, JSS, AllAround and friends; my brain is starting to hurt.

totallackey thinks he understands physics but can't work out how to use the quoting system on here even though there's a preview option and you can edit. Doesn't exactly build confidence in his abilities...
I don't know if he's trolling or just incredibly stubborn but it's pointless pursuing things further.
He has been shown videos of rockets working in vacuums and has simply said the prove his point that they do not.
The physics behind why they work in a vacuum has been explained in so many ways and he has either not understood any of them or not tried to. All he's done is repeat the same few stock phrases about free expansion and work despite repeated explanations from people who understand this better than I why the result he is pinning all his hopes on does not apply to rockets.
I suggest that we are just going to continue to go round in circles on this.

Considering I have addressed each of the sources offered and each of those sources have been objectively explained (by yours truly) to be falsely interpreted by everyone of you (except somerled) and the video evidence offered by you in particular clearly demonstrates that rockets cannot work in a vacuum...I suggest you will be the one going around in circles...by all means, go ahead.

Me, I know what direction I am headed.

[totallackey]

Let's repost the claptrap source and see what it defines as being isentropic at the nozzle:

""Isentropic flows occur when the change in flow variables is small and gradual, such as the ideal flow through the nozzle shown above. The generation of sound waves is an isentropic process. A supersonic flow that is turned while the flow area increases is also isentropic. We call this an isentropic expansion because of the area increase."

The paragraph you quote is not a "definition of what is isentropic at the nozzle"; it is only elaborating on what (some) isentropic flows are.
If you follow the embedded link in "the generation of sound waves is an isentropic process.", it explains the isentropic nature of sound waves in more detail.

Yeah, which is what is isentropic at the nozzle.

Period.

Now, knowing that gas released to the confines of a vacuum does 0 work, and knowing the entirety of the nozzle (both the outside of the bell and the inside of the bell) are exposed to vacuum, neither of the conditions for "isentropic process, " are met.

The gas is not released, it is expelled. => "does 0 work" does not apply.

All gas, when released from its container, is expelled.

Take a CO₂cartridge and pop a hole in it.

When you do that, the gas is expelled under great force.

The gas goes one way, the cartridge goes the other...INSTANTLY!!!

Now do the same thing when the CO₂cartridge is in a vacuum...nothing, nada, zilch, bupkus...

You are wrong, as usual...

Gas released or expelled to a vacuum does 0 work.

Once the rocket is operating, the inside of the "bell" will be filled with gas. => no vacuum.

Wrong...the bell has an opening and when, as claimed by mystical outer space rocket engineers, it is in outer space...that opening is in a vacuum...and gas, when coming from one container through an opening to the presence of a vacuum, freely disperses...and does 0 work...

Even after leaving the bell there will not (immediately) be exposed to vacuum as the dispersing exhaust is still there.

You're really trying, but sorry...you got this all wrong...

The video evidence is clear and the science is clear.

You're wrong.

Give it up.

[iCare]

The paragraph you quote is not a "definition of what is isentropic at the nozzle"; it is only elaborating on what (some) isentropic flows are.
If you follow the embedded link in "the generation of sound waves is an isentropic process.", it explains the isentropic nature of sound waves in more detail.

Yeah, which is what is isentropic at the nozzle.

It doesn't matter, if this happens at the nozzle. It is not all that happens at the nozzle and it is not the most relevant aspect for rocket propulsion.
Please stop looking only at cherry-picked bits an pieces from sources and taking them out of context.

Period.

Adding "Period" to a wrong statement doesn't make it any less wrong.
It just shows your inability to discuss a topic objectively.

The gas is not released, it is expelled. => "does 0 work" does not apply.

All gas, when released from its container, is expelled.

That may be the case colloquially speaking.
The distinction made here is between expelled as in "forced through a nozzle" (rocket propulsion) in contrast to being released as in "expanding without restriction" (free expansion, if being released to a vacuum).

Take a CO₂cartridge and pop a hole in it.
When you do that, the gas is expelled under great force.
The gas goes one way, the cartridge goes the other...INSTANTLY!!!

Not quite instantly, but given the mass/force relation the delay is likely not obvious.

Now do the same thing when the CO₂cartridge is in a vacuum...nothing, nada, zilch, bupkus...
You are wrong, as usual...

It is you, who is wrong.
That is (in principle) how a cold gas thruster works.

Gas released or expelled to a vacuum does 0 work.

See above:
released => same amount of gas, no restriction => no work done when freely expanding.
forced: => increasing amount of gas (CO₂ is in liquid form while in the cartridge.), restricted by nozzle => work done

Once the rocket is operating, the inside of the "bell" will be filled with gas. => no vacuum.

Wrong...the bell has an opening and when, as claimed by mystical outer space rocket engineers, it is in outer space...that opening is in a vacuum...and gas, when coming from one container through an opening to the presence of a vacuum, freely disperses...and does 0 work...

See above ... if the nozzle is restricting the flow, the gas does not disperse freely, but is forced through the opening; what happens at the back end of the bell is (mostly) irrelevant to propulsion. => 0 work does not apply.
You are confusing different aspects of the propulsion process.
So please, do take the time to look at the whole propulsion process to see what kind of process takes place exactly where and when and which laws are relevant at those stages.

You're really trying, but sorry...you got this all wrong...

The fact that I can explain it in detail based on accepted scientific laws indicates, that I got it right.
And honestly, it doesn't take a lot of trying - this is straightforward physics.
Keeps me wondering, why you're having such a hard time understanding it ...

The video evidence is clear and the science is clear.

Indeed it is and it is fully in line with what I keep trying to explain in the hopes that - at one point - you will understand it.

You're wrong.

See above.
My reasoning is based on the correct and logically consistent application of laws of science.  => I'm right.
In contrast your reasoning is based on your mantra "vacuum => always free expansion => never any work" which is in conflict with (at least) Joule's Law and Newton's Laws - as frequently and validly deduced. => You're wrong.

Give it up.

As long as you keep making invalid, unsupported claims and there's still a sliver of hope, that you might get past your preconceived notions and see the truth, I intend to keep it up.


iC

[totallackey]

The paragraph you quote is not a "definition of what is isentropic at the nozzle"; it is only elaborating on what (some) isentropic flows are.
If you follow the embedded link in "the generation of sound waves is an isentropic process.", it explains the isentropic nature of sound waves in more detail.

Yeah, which is what is isentropic at the nozzle.

It doesn't matter, if this happens at the nozzle. It is not all that happens at the nozzle and it is not the most relevant aspect for rocket propulsion.
Please stop looking only at cherry-picked bits an pieces from sources and taking them out of context.

You are correct.

There is something else that takes place at the nozzle when a rocket is in operation.

Hot gas is being expelled.

And while the rocket is in operation in a pressurized environment, a plume is formed.

And when a plume is formed, the rocket can react to the plume.

When the rocket is exposed to a vacuum, no plume can be be formed...because gas expelled into a vacuum freely expands.

Period.

Adding "Period" to a wrong statement doesn't make it any less wrong.
It just shows your inability to discuss a topic objectively.

Except in cases where I am right and you are wrong and the only responsible thing to type is "Period."

Like in this instance.

The gas is not released, it is expelled. => "does 0 work" does not apply.

All gas, when released from its container, is expelled.

That may be the case colloquially speaking.

No, it is the case, literally speaking.

Period.

The distinction made here is between expelled as in "forced through a nozzle" (rocket propulsion) in contrast to being released as in "expanding without restriction" (free expansion, if being released to a vacuum).

Gas, when placed in any container, is under pressure.

When said gas is expelled from said container, it comes out of said container, under pressure.

You claim that said gas can be provided more "oomph," when coming out of a rocket in order to miraculously overcome the law that states gas will freely expand in a vacuum...

Your claim is proven wrong, right in front of our very eyes, courtesy of these fine videos found in the thread.

Period.

Take a CO₂cartridge and pop a hole in it.
When you do that, the gas is expelled under great force.
The gas goes one way, the cartridge goes the other...INSTANTLY!!!

Not quite instantly, but given the mass/force relation the delay is likely not obvious.

Now do the same thing when the CO₂cartridge is in a vacuum...nothing, nada, zilch, bupkus...
You are wrong, as usual...

It is you, who is wrong.
That is (in principle) how a cold gas thruster works.

Yeah, it is...

So, GREAT NEWS!!!

Take a CO₂ cartridge and have them open it up in a vacuum...see what happens...time it...compare...

I am not going to bother with the rest of your post now...I will later...probably already linking to prior written replies since you first posted.

[BRrollin]

Let's repost the claptrap source and see what it defines as being isentropic at the nozzle:

""Isentropic flows occur when the change in flow variables is small and gradual, such as the ideal flow through the nozzle shown above. The generation of sound waves is an isentropic process. A supersonic flow that is turned while the flow area increases is also isentropic. We call this an isentropic expansion because of the area increase."

The paragraph you quote is not a "definition of what is isentropic at the nozzle"; it is only elaborating on what (some) isentropic flows are.
If you follow the embedded link in "the generation of sound waves is an isentropic process.", it explains the isentropic nature of sound waves in more detail.

Yeah, which is what is isentropic at the nozzle.

Period.

Now, knowing that gas released to the confines of a vacuum does 0 work, and knowing the entirety of the nozzle (both the outside of the bell and the inside of the bell) are exposed to vacuum, neither of the conditions for "isentropic process, " are met.

The gas is not released, it is expelled. => "does 0 work" does not apply.

All gas, when released from its container, is expelled.

Take a CO₂cartridge and pop a hole in it.

When you do that, the gas is expelled under great force.

The gas goes one way, the cartridge goes the other...INSTANTLY!!!

Now do the same thing when the CO₂cartridge is in a vacuum...nothing, nada, zilch, bupkus...

You are wrong, as usual...

Gas released or expelled to a vacuum does 0 work.

Once the rocket is operating, the inside of the "bell" will be filled with gas. => no vacuum.

Wrong...the bell has an opening and when, as claimed by mystical outer space rocket engineers, it is in outer space...that opening is in a vacuum...and gas, when coming from one container through an opening to the presence of a vacuum, freely disperses...and does 0 work...

Even after leaving the bell there will not (immediately) be exposed to vacuum as the dispersing exhaust is still there.

You're really trying, but sorry...you got this all wrong...

The video evidence is clear and the science is clear.

You're wrong.

Give it up.

Imagine a container with a barrier cutting it in half. In one half is a gas, and the other is a vacuum. If we suddenly remove the barrier, the. The gas expands into the vacuum, and zero work is involved.

I think this is the idea that you are talking about. And I absolutely agree with you.

The difference between this thought experiment and a rocket is that the gas is propelled from the rocket with a velocity. Since the rocket fuel is burned (a deflagration) which converts stored chemical potential energy into kinetic energy.

Since the rocket + fuel starts off with no initial momentum, as the fuel leaves in one direction with a velocity, there must be a corresponding momentum of the rocket in the other direction to cancel it.

Once the fuel leaves, it freely expands into the vacuum and does no work.

So in my opinion, you are both correct - you’re just looking at different parts of the process.

[iCare]

And when a plume is formed, the rocket can react to the plume.

Please do take my advice and take a look at the different stages of the process. Propulsion does not happen by interaction with the plume.

When the rocket is exposed to a vacuum, no plume can be be formed...because gas expelled into a vacuum freely expands.

If it is expelled, it does not expand freely (see below).
Even if it would expand freely, that is not an instantaneous process, so a plume will form in any case.
So even if your assumption of free expansion was right (which isn't), the result still wouldn't be what you suggest (no plume).

The distinction made here is between expelled as in "forced through a nozzle" (rocket propulsion) in contrast to being released as in "expanding without restriction" (free expansion, if being released to a vacuum).

Gas, when placed in any container, is under pressure.
When said gas is expelled from said container, it comes out of said container, under pressure.
You claim that said gas can be provided more "oomph,"

Indeed.
Unlike in free expansion, where the amount of gas and the energy contained in it, are (as Joule requires) constant, the exothermic reaction in a fuel burning rocket increases the temperature and amount of gas. That would qualify as adding "oomph", I'd say.
It definitely raises the pressure in the combustion chamber significantly. More gas, at higher temperature and higher pressure should have more "oomp" than less gas at less temperature and less pressure, shouldn't it?
It not only seems logical (and common sense), that adding energy to gas must result in more "oomph", it is also scientifically required to maintain conservation of energy.

when coming out of a rocket in order to miraculously overcome the law that states gas will freely expand in a vacuum...

You need to get your understanding of basic science straight:
There is no law to overcome; there is no law stating, that gas can only expand freely into a vacuum.
Gas does not need to be forced into a vacuum, because - due to its nature - it will expand anyway, trying to reach equal distribution.
(If the available volume - e.g. space - is much larger then the volume the available gas can fill that way, that will change it behavior. Hence releasing gas into an enclosed vacuum is different from releasing it into an endless vacuum.)
If it expands freely into a vacuum, it will do no work. That does not mean it must only expand freely.
If you let go of a ball, you don't need to push it to fall down freely (when it bounces back to the same height, its energy is the same again); that doesn't mean you can't still add energy and throw it down (it will bounce back higher, having gained energy, as you added energy).
So the energy added by the endothermic chemical reaction must have an effect, i.e. forcing the gas through the nozzle instead of having it "leisurely" expand under lower pressure.
That effect - in an atmosphere - is to accelerate the rocket. If that effect is - as you claim - doesn't take place in a vacuum, you need to explain where that additional energy "miraculously" goes to, if it doesn't do any work:

All relevant factors are (in essence) the same ... so where does the force (that obviously is at work in an atmosphere) disappear to?

It disappears when gas is released into a vacuum.

Force doesn't just "disappear". Where does it go to?

Your claim is proven wrong, right in front of our very eyes, courtesy of these fine videos found in the thread.

As stated before, that may be what you want to see in them, but it cannot validly be concluded from those videos (and it is not what the majority of people in this thread see in those videos).
Unless you have to add any actual reasoning to reiterating your disputed claim, the "Period." is on you for being wrong and stuck with it.

Take a CO₂ cartridge and have them open it up in a vacuum...see what happens...time it...compare...

Sadly I don't have access to a total vacuum. But as I'm in full accordance with the relevant scientific laws, there is no doubt about the outcome - the  CO₂ cartridge would accelerate pretty much the same way.
But you sound pretty sure of the result "no acceleration" (which would be in direct violation of Newton's 3rd Law), so - if only to prove me wrong - you can surely provide some evidence, can't you?

I am not going to bother with the rest of your post now...I will later...probably already linking to prior written replies since you first posted.

If you can't add anything substantial beyond reiterating your mantra "vacuum => always free expansion => never any work", please don't go to any effort on my account.
Rather use your time to learn how to objectively analyze a scientific problem how to read, understand and correctly apply scientific laws to solve it.

iC

[somerled]

Let's repost the claptrap source and see what it defines as being isentropic at the nozzle:

""Isentropic flows occur when the change in flow variables is small and gradual, such as the ideal flow through the nozzle shown above. The generation of sound waves is an isentropic process. A supersonic flow that is turned while the flow area increases is also isentropic. We call this an isentropic expansion because of the area increase."

The paragraph you quote is not a "definition of what is isentropic at the nozzle"; it is only elaborating on what (some) isentropic flows are.
If you follow the embedded link in "the generation of sound waves is an isentropic process.", it explains the isentropic nature of sound waves in more detail.

Yeah, which is what is isentropic at the nozzle.

Period.

Now, knowing that gas released to the confines of a vacuum does 0 work, and knowing the entirety of the nozzle (both the outside of the bell and the inside of the bell) are exposed to vacuum, neither of the conditions for "isentropic process, " are met.

The gas is not released, it is expelled. => "does 0 work" does not apply.

All gas, when released from its container, is expelled.

Take a CO₂cartridge and pop a hole in it.

When you do that, the gas is expelled under great force.

The gas goes one way, the cartridge goes the other...INSTANTLY!!!

Now do the same thing when the CO₂cartridge is in a vacuum...nothing, nada, zilch, bupkus...

You are wrong, as usual...

Gas released or expelled to a vacuum does 0 work.

Once the rocket is operating, the inside of the "bell" will be filled with gas. => no vacuum.

Wrong...the bell has an opening and when, as claimed by mystical outer space rocket engineers, it is in outer space...that opening is in a vacuum...and gas, when coming from one container through an opening to the presence of a vacuum, freely disperses...and does 0 work...

Even after leaving the bell there will not (immediately) be exposed to vacuum as the dispersing exhaust is still there.

You're really trying, but sorry...you got this all wrong...

The video evidence is clear and the science is clear.

You're wrong.

Give it up.

Imagine a container with a barrier cutting it in half. In one half is a gas, and the other is a vacuum. If we suddenly remove the barrier, the. The gas expands into the vacuum, and zero work is involved.

I think this is the idea that you are talking about. And I absolutely agree with you.

The difference between this thought experiment and a rocket is that the gas is propelled from the rocket with a velocity. Since the rocket fuel is burned (a deflagration) which converts stored chemical potential energy into kinetic energy.

Since the rocket + fuel starts off with no initial momentum, as the fuel leaves in one direction with a velocity, there must be a corresponding momentum of the rocket in the other direction to cancel it.

Once the fuel leaves, it freely expands into the vacuum and does no work.

So in my opinion, you are both correct - you’re just looking at different parts of the process.

This "thought experiment" was carried out ,in reality , by James Joule . It's how science knows that a rocket engine won't produce thrust in a vacuum. It's a physical law , Joules law , amply demonstrated in all videos attempting to show rocket engines working in a vacuum.

In these videos the rocket fuel will not sustain a chemical reaction in a vacuum - even with it's own oxidizer . Pressure is required for combustion which is why we see these  rocket engines being sealed under pressure of air -turned into bombs - in order for the fuel burn to occur , or explode.

The principle of conservation of momentum will never produce a force and will never accelerate a rocket in a vacuum .

[iCare]

Imagine a container with a barrier cutting it in half. In one half is a gas, and the other is a vacuum. If we suddenly remove the barrier, the. The gas expands into the vacuum, and zero work is involved.
I think this is the idea that you are talking about. And I absolutely agree with you.

I'm not sure how long you have been reading along or how far you backtraced this discussion - that specific "image" came up around page 14.
And it has been pointed out at the time, that there is an obvious difference between free expansion (top half) and a rocket engine (bottom half).

As far as I remember nobody has doubted Joule's Law, i.e. no work being done if gas expands freely.
Gas may expand freely, but it can also expand otherwise.

The difference between this thought experiment and a rocket is that the gas is propelled from the rocket with a velocity. Since the rocket fuel is burned (a deflagration) which converts stored chemical potential energy into kinetic energy.
Since the rocket + fuel starts off with no initial momentum, as the fuel leaves in one direction with a velocity, there must be a corresponding momentum of the rocket in the other direction to cancel it.

Agreed, that would be a direct result of Newton's Third Law.

Once the fuel leaves, it freely expands into the vacuum and does no work.

Now, that requires some pondering ...
It is not relevant for rocket propulsion, as this part of the process takes place "after the fact", but is it really fully covered by free expansion?
The exhausted gas will disperse, pretty much in accordance with free expansion, but it also still carries momentum from being expelled - if it was to hit some random object in space, wouldn't it transfer that momentum and do work?
Also "no work" is requires an stable end state, which will never be reached in endless space. (We went back and forth about this at about the same time we were discussing the referenced image.)
Admittedly, rather philosophical questions with little bearing on the question at hand (if rockets in a vacuum). 

So in my opinion, you are both correct - you’re just looking at different parts of the process.

I agree with your explanation of the process (except, maybe for the philosophical part) and I'll leave it to totallackey to disagree with you, if he so chooses.
However, his conclusion is "rockets do not work in a vacuum" and my conclusion is "rockets do work in a vacuum" we cannot both be correct.

iC

[BRrollin]

Imagine a container with a barrier cutting it in half. In one half is a gas, and the other is a vacuum. If we suddenly remove the barrier, the. The gas expands into the vacuum, and zero work is involved.
I think this is the idea that you are talking about. And I absolutely agree with you.

I'm not sure how long you have been reading along or how far you backtraced this discussion - that specific "image" came up around page 14.
And it has been pointed out at the time, that there is an obvious difference between free expansion (top half) and a rocket engine (bottom half).

As far as I remember nobody has doubted Joule's Law, i.e. no work being done if gas expands freely.
Gas may expand freely, but it can also expand otherwise.

The difference between this thought experiment and a rocket is that the gas is propelled from the rocket with a velocity. Since the rocket fuel is burned (a deflagration) which converts stored chemical potential energy into kinetic energy.
Since the rocket + fuel starts off with no initial momentum, as the fuel leaves in one direction with a velocity, there must be a corresponding momentum of the rocket in the other direction to cancel it.

Agreed, that would be a direct result of Newton's Third Law.

Once the fuel leaves, it freely expands into the vacuum and does no work.

Now, that requires some pondering ...
It is not relevant for rocket propulsion, as this part of the process takes place "after the fact", but is it really fully covered by free expansion?
The exhausted gas will disperse, pretty much in accordance with free expansion, but it also still carries momentum from being expelled - if it was to hit some random object in space, wouldn't it transfer that momentum and do work?
Also "no work" is requires an stable end state, which will never be reached in endless space. (We went back and forth about this at about the same time we were discussing the referenced image.)
Admittedly, rather philosophical questions with little bearing on the question at hand (if rockets in a vacuum). 

So in my opinion, you are both correct - you’re just looking at different parts of the process.

I agree with your explanation of the process (except, maybe for the philosophical part) and I'll leave it to totallackey to disagree with you, if he so chooses.
However, his conclusion is "rockets do not work in a vacuum" and my conclusion is "rockets do work in a vacuum" we cannot both be correct.

iC

So sorry. I didn’t mean to duplicate a post. I guess after 15 pages it gets hard to keep track of everything that’s been said.

Yeah I just wanted to find some common ground between everyone, since it has become so contentious (I was part of that, of course).

I agree with your added comments, and although they are about what happens after the propulsion event, the physics still seems relevant.

From how I understand it, a gas freely expanding in a vacuum has a velocity, no matter what. If it is a stable state, then the velocity distribution is maxwellian, but obviously for a rocket it wouldn’t be.

So in the compartment example, it expands with a maxwell distribution. And if it hits an object, then work would be done I suppose. But then it really wasn’t a vacuum, right?

I see the rocket gas as the same thing - just a velocity determined by the deflagration.

I don’t think the distribution affects the thermodynamic behavior of free expansion, but I could be wrong.

[JSS]

This "thought experiment" was carried out ,in reality , by James Joule . It's how science knows that a rocket engine won't produce thrust in a vacuum. It's a physical law , Joules law , amply demonstrated in all videos attempting to show rocket engines working in a vacuum.

In these videos the rocket fuel will not sustain a chemical reaction in a vacuum - even with it's own oxidizer . Pressure is required for combustion which is why we see these  rocket engines being sealed under pressure of air -turned into bombs - in order for the fuel burn to occur , or explode.

The principle of conservation of momentum will never produce a force and will never accelerate a rocket in a vacuum .

Do you have a citation for this experiment carried out by James Prescott Joule back in the 1800s?

Do you have anything more specific than "Joules Law" to clarify what it is you are talking about?

I've looked and not found anything, not that it matters much as rocket science and science in general has advanced rather a lot in 200 years.

[somerled]

Nasa can no longer put man above low earth orbit apparently. I suppose that is classed as an advance in a reverse direction .

[JSS]

Nasa can no longer put man above low earth orbit apparently. I suppose that is classed as an advance in a reverse direction .

So I'm assuming that means no, you have no citations or references to back up anything you said.

[AATW]

This "thought experiment" was carried out ,in reality , by James Joule . It's how science knows that a rocket engine won't produce thrust in a vacuum.

Great.
So now all you have to do is provide some evidence from a credible scientist which specifically says that rockets cannot work in a vacuum. Then this matter can be resolved once and for all.
If science “knows” this then that should be pretty simple for you.

[BRrollin]

Let's repost the claptrap source and see what it defines as being isentropic at the nozzle:

""Isentropic flows occur when the change in flow variables is small and gradual, such as the ideal flow through the nozzle shown above. The generation of sound waves is an isentropic process. A supersonic flow that is turned while the flow area increases is also isentropic. We call this an isentropic expansion because of the area increase."

The paragraph you quote is not a "definition of what is isentropic at the nozzle"; it is only elaborating on what (some) isentropic flows are.
If you follow the embedded link in "the generation of sound waves is an isentropic process.", it explains the isentropic nature of sound waves in more detail.

Yeah, which is what is isentropic at the nozzle.

Period.

Now, knowing that gas released to the confines of a vacuum does 0 work, and knowing the entirety of the nozzle (both the outside of the bell and the inside of the bell) are exposed to vacuum, neither of the conditions for "isentropic process, " are met.

The gas is not released, it is expelled. => "does 0 work" does not apply.

All gas, when released from its container, is expelled.

Take a CO₂cartridge and pop a hole in it.

When you do that, the gas is expelled under great force.

The gas goes one way, the cartridge goes the other...INSTANTLY!!!

Now do the same thing when the CO₂cartridge is in a vacuum...nothing, nada, zilch, bupkus...

You are wrong, as usual...

Gas released or expelled to a vacuum does 0 work.

Once the rocket is operating, the inside of the "bell" will be filled with gas. => no vacuum.

Wrong...the bell has an opening and when, as claimed by mystical outer space rocket engineers, it is in outer space...that opening is in a vacuum...and gas, when coming from one container through an opening to the presence of a vacuum, freely disperses...and does 0 work...

Even after leaving the bell there will not (immediately) be exposed to vacuum as the dispersing exhaust is still there.

You're really trying, but sorry...you got this all wrong...

The video evidence is clear and the science is clear.

You're wrong.

Give it up.

Imagine a container with a barrier cutting it in half. In one half is a gas, and the other is a vacuum. If we suddenly remove the barrier, the. The gas expands into the vacuum, and zero work is involved.

I think this is the idea that you are talking about. And I absolutely agree with you.

The difference between this thought experiment and a rocket is that the gas is propelled from the rocket with a velocity. Since the rocket fuel is burned (a deflagration) which converts stored chemical potential energy into kinetic energy.

Since the rocket + fuel starts off with no initial momentum, as the fuel leaves in one direction with a velocity, there must be a corresponding momentum of the rocket in the other direction to cancel it.

Once the fuel leaves, it freely expands into the vacuum and does no work.

So in my opinion, you are both correct - you’re just looking at different parts of the process.

This "thought experiment" was carried out ,in reality , by James Joule . It's how science knows that a rocket engine won't produce thrust in a vacuum. It's a physical law , Joules law , amply demonstrated in all videos attempting to show rocket engines working in a vacuum.

In these videos the rocket fuel will not sustain a chemical reaction in a vacuum - even with it's own oxidizer . Pressure is required for combustion which is why we see these  rocket engines being sealed under pressure of air -turned into bombs - in order for the fuel burn to occur , or explode.

The principle of conservation of momentum will never produce a force and will never accelerate a rocket in a vacuum .

Hi Somerled. Just saw your reply (the posts after came fast) and so wanted to respond.

Isn’t the fuel in the rockets under pressure though? That’s my understanding. But it sounds like you disagree that deflagration could happen in a vacuum?

So when you say the principle of Momentum cannot produce a force, do you mean in general or just in a rocket-vacuum situation?

Because I see two topics here for discussion:

1) deflagration cannot proceed in a vacuum.

2) momentum cannot produce forces.

Both are required to happen for a rocket to work, and so maybe it would be useful to address these separately?

That is, of course, if I understand you right. Do let me know!

[iCare]

So sorry. I didn’t mean to duplicate a post. I guess after 15 pages it gets hard to keep track of everything that’s been said.

No need to be sorry. I didn't want to criticize  your effort (I hope you didn't take it that way), just make you aware that it has come up before.
Here it says page 30, so believe me, I know the feeling.

Yeah I just wanted to find some common ground between everyone, since it has become so contentious (I was part of that, of course).

A commendable effort; it usually makes sense to get the things we agree on out of the way and focus on the aspects we disagree about.
At this point the "uncommon ground" has already been pretty much established as "does free expansion prevent rockets from working or not"? (It does not.)
There was some side discussion, if fuel would burn in a vacuum. (Rocket fuel will burn in a rocket in a vacuum.)

From how I understand it, a gas freely expanding in a vacuum has a velocity, no matter what. If it is a stable state, then the velocity distribution is maxwellian, but obviously for a rocket it wouldn’t be.

If gas is expanding, it is obviously moving, so it would have to have a velocity.
With maxwell you're not looking a "the gas" as such, but the molecules it is composed of.

In the case of a rocket those molecules will share a common velocity vector by having been expelled together (it will, of course, not be exactly identical for each molecule).
This is significant for propulsion and has recently become known as "oomph" in this thread.

They will also have individual (comparatively small) velocity vectors due to the way gas molecules constantly move.
This part will make the gas expand (freely) and is not significant for propulsion.

So in the compartment example, it expands with a maxwell distribution. And if it hits an object, then work would be done I suppose. But then it really wasn’t a vacuum, right?

It wouldn't be a total vacuum and as the object would be "hit" in an non-stable state, I guess work may be done depending on the circumstances of the experiment. 

I see the rocket gas as the same thing - just a velocity determined by the deflagration.
I don’t think the distribution affects the thermodynamic behavior of free expansion, but I could be wrong.

What kind of distribution and behavior are you referring to exactly?

iC

[BRrollin]

So sorry. I didn’t mean to duplicate a post. I guess after 15 pages it gets hard to keep track of everything that’s been said.

No need to be sorry. I didn't want to criticize  your effort (I hope you didn't take it that way), just make you aware that it has come up before.
Here it says page 30, so believe me, I know the feeling.

Yeah I just wanted to find some common ground between everyone, since it has become so contentious (I was part of that, of course).

A commendable effort; it usually makes sense to get the things we agree on out of the way and focus on the aspects we disagree about.
At this point the "uncommon ground" has already been pretty much established as "does free expansion prevent rockets from working or not"? (It does not.)
There was some side discussion, if fuel would burn in a vacuum. (Rocket fuel will burn in a rocket in a vacuum.)

From how I understand it, a gas freely expanding in a vacuum has a velocity, no matter what. If it is a stable state, then the velocity distribution is maxwellian, but obviously for a rocket it wouldn’t be.

If gas is expanding, it is obviously moving, so it would have to have a velocity.
With maxwell you're not looking a "the gas" as such, but the molecules it is composed of.

In the case of a rocket those molecules will share a common velocity vector by having been expelled together (it will, of course, not be exactly identical for each molecule).
This is significant for propulsion and has recently become known as "oomph" in this thread.

They will also have individual (comparatively small) velocity vectors due to the way gas molecules constantly move.
This part will make the gas expand (freely) and is not significant for propulsion.

So in the compartment example, it expands with a maxwell distribution. And if it hits an object, then work would be done I suppose. But then it really wasn’t a vacuum, right?

It wouldn't be a total vacuum and as the object would be "hit" in an non-stable state, I guess work may be done depending on the circumstances of the experiment. 

I see the rocket gas as the same thing - just a velocity determined by the deflagration.
I don’t think the distribution affects the thermodynamic behavior of free expansion, but I could be wrong.

What kind of distribution and behavior are you referring to exactly?

iC

Let’s see, I think I agree with all of your comments - any differences are probably just semantical.

By different velocity distribution, I just meant not maxwellian - because it is not a thermally averaged state. I don’t know what the distribution would actually be for a rocket, so I can’t help there.

But I was thinking that once the gas leaves the rocket then it would freely expand just like the compartment gas. Hence, the relevant topic is what happens before then.

Of course, the density distribution wouldn’t look that same, since there rocket gas is sent isotropically. I just mean from a thermodynamics expansion point of view.

Hope that makes sense...

[J-Man]

There is plenty of evidence that the moon landings were hoaxes, pretending that rockets can't work in vacuum distracts from the real evidence.

American Moon is the best documentary on the subject https://www.bitchute.com/video/eZramDBFkXRU/

Great Video proving we never went to the moon. NASA fakery alive and well.

[AATW]

Great Video proving we never went to the moon. NASA fakery alive and well.

Good ole confirmation bias.
I have responded to the video - or bits of it.
If you actually bother to look into these things they really are very easily explained.