It's 2015 and you aren't even close to owning a Spaceship

What can I do?

Luckyfred keeps asking me to answer a question that refers to something I never said, i.e. that the combustion chamber is insulated.

I was referring to the fuel tank, & it's similarity to the initial conditions of experiments proving free expansion.

Look:

Quote from: Mainframes on November 27, 2015, 04:16:01 AM

It is not an insulated closed chamber.

Its fuel tank is.

Which is what I was referring to; please learn to read.

If that's not trolling, what is?

Also, I have not reported anyone since your warning, & rarely did so before; so it's not me spamming you.

More derailing & Gibberish...

Does a rocket in 'space' work by introducing a Gas into a Vacuum?

Simple question.

Simple answer.

No.

A rocket in space works by accelerating mass out the back.  Whether that mass is solid, liquid, gas or plasma is irrelevant, the principle is the same.

in fuel tanks propallant is in liquid state.
free expansion talks about gas.
propellant becomes a gas in the combustion chamber, which is not insulated so u cannot apply free expansion to the nozzle.

Quote from: markjo on November 25, 2015, 10:19:27 PM

Free expansion says that when the system reaches equilibrium, the total work done is zero.

Then this:

Quote from: markjo on November 26, 2015, 06:19:53 AM

  A rocket that is constantly ejecting large quantities of gas is not at equilibrium, therefore the total work being done is not yet zero.

Then have a think about it...

Can you see what he did there?

Yes, I showed that your free expansion argument does not apply to rockets in a vacuum.

Now would you care to add something to the discussion?

Quote from: Papa Legba on November 27, 2015, 06:13:56 AM

Does a rocket in 'space' work by introducing a Gas into a Vacuum?

Simple question.

Simple answer.

No.

A rocket in space works by accelerating mass out the back.  Whether that mass is solid, liquid, gas or plasma is irrelevant, the principle is the same.

So a rocket in 'space' is NOT introducing a Gas into a vacuum?

Shouldn't you tell NASA that?

More importantly; how, exactly, does the rocket accelerate this irrelevantly-composed mass out the back?

I showed that your free expansion argument does not apply to rockets in a vacuum.

Quite the opposite.

Read what you wrote again:

Free expansion says that when the system reaches equilibrium, the total work done is zero.

Then read this:

  A rocket that is constantly ejecting large quantities of gas is not at equilibrium, therefore the total work being done is not yet zero.

I see what you did there!

LOL!!!

So a rocket in 'space' is NOT introducing a Gas into a vacuum?

Yes a rocket introduces gas into a vacuum, but no, that isn't how it works.

A car introduces gas into the atmosphere, but that isn't what drives the wheels.

More importantly; how, exactly, does the rocket accelerate this irrelevantly-composed mass out the back?

By various methods depending on the type of rocket, but most commonly by the process of burning fuel and oxidizer in a combustion chamber.

Quote from: markjo on November 27, 2015, 08:51:11 AM

I showed that your free expansion argument does not apply to rockets in a vacuum.

Quite the opposite.

Read what you wrote again:

I know what I wrote, and I stand by it.  Perhaps you would care explain why you think I'm wrong instead of spamming the same thing over and over again.

This is assuming either he knows what he's talking about or he isn't an obnoxious troll.

Quote from: Papa Legba on November 27, 2015, 09:10:38 AM

More importantly; how, exactly, does the rocket accelerate this irrelevantly-composed mass out the back?

By various methods depending on the type of rocket, but most commonly by the process of burning fuel and oxidizer in a combustion chamber.

Oh; so a rocket works 'by various methods' does it?

Could you be a bit more vague?

Do any of these 'various methods' involve the creation of Pressure, perhaps?

I know what I wrote, and I stand by it.  Perhaps you would care explain why you think I'm wrong instead of spamming the same thing over and over again.

LOL!!!

No; I'll just let you sweat on it...

Anyone intelligent will already know what I mean.

As for the unintelligent ones, they'll probably think there's 'rokkits' in 'shpayze' whatever I say...

So who cares about them?

Again, though, for lulz...

First, this:

Free expansion says that when the system reaches equilibrium, the total work done is zero.

Then, this:

  A rocket that is constantly ejecting large quantities of gas is not at equilibrium, therefore the total work being done is not yet zero.

"not yet zero..."

*snicker!*

Anyhoo; does a rocket in a vacuum work by creating Pressure, markjo?

If not, then how is the Mass you state it throws out the back Accelerated?

The mass is accelerated out the back as a result of combustion of the vapour phase components that increase in energy and volume. Pressure is a result of the combustion.

Quote from: markjo on November 27, 2015, 09:56:18 AM

Quote from: Papa Legba on November 27, 2015, 09:10:38 AM

More importantly; how, exactly, does the rocket accelerate this irrelevantly-composed mass out the back?

By various methods depending on the type of rocket, but most commonly by the process of burning fuel and oxidizer in a combustion chamber.

Oh; so a rocket works 'by various methods' does it?

Do you think that an ion rocket works the same way as a solid fuel rocket?

Do any of these 'various methods' involve the creation of Pressure, perhaps?

Do you have such a short attention span that you can't finish reading a sentence that you quoted?  I said "most commonly by the process of burning fuel and oxidizer in a combustion chamber".  So yes, rocket engines that burn fuel and oxidizer create pressure in a combustion chamber.

Quote from: markjo on November 27, 2015, 09:56:18 AM

I know what I wrote, and I stand by it.  Perhaps you would care explain why you think I'm wrong instead of spamming the same thing over and over again.

LOL!!!

No; I'll just let you sweat on it...

In other words, you can't.  Good to know.

"not yet zero..."

*snicker!*

Correct.  The burning of fuel and transferring heat to the rocket engine are considered work.

Anyhoo; does a rocket in a vacuum work by creating Pressure, markjo?

If not, then how is the Mass you state it throws out the back Accelerated?

Does it really matter how the mass being ejected out the back is accelerated?  The fact that it is accelerated is the important part.

There are also other kind of propulsion. Ion propulsion for example works by accelerating ions thanks to an electrostatic or electromagnetic field.

Most common type of rockets works by burning fuel and oxidizer. Combustion increases the energy(high temperature and pressure) BUT the propulsion is created thanks to the nozzle, which turns this energy into kinetic energy. Which means that through the nozzle the gas decreases its pressure and temperature and accelerates

Do you think that an ion rocket works the same way as a solid fuel rocket?

Changing the subject to another sci-fi fantasy, are we?

That's not like you...

yes, rocket engines that burn fuel and oxidizer create pressure in a combustion chamber.

They both 'burn'  AND 'create pressure'?

In a vacuum?

LOL!!!

Have you consulted the Laws of Physics on this matter?

In other words, you can't.

No; I can & I did.

You're just trying to pretend I didn't...

Or are you really too dumb to know?

Read again:

Free expansion says that when the system reaches equilibrium, the total work done is zero.

Then read this again:

  A rocket that is constantly ejecting large quantities of gas is not at equilibrium, therefore the total work being done is not yet zero.

Then note the words 'not yet zero...'

Then LOL!!!

Does it really matter how the mass being ejected out the back is accelerated?

I can't believe you wrote this; but then again, I can't believe you write anything...

YES, it does matter...

When you're trying to explain how motion can be produced in a Vacuum, which is the total absence of all mass, pressure, matter, or any other means of creating friction or resistance, I'd say that every single thing 'matters'.

Because such a concept sounds like complete baloney to myself & any other sane person out there...

Thus, I will keep grilling you on the details until you give a satisfactory explanation for your claims.

You haven't yet, & I doubt you ever will...

You know why?

Because it is Impossible.

What law of physics is it that prevents a fuel and oxidiser combusting when in close proximity?

Quote from: markjo on November 27, 2015, 01:16:54 PM

yes, rocket engines that burn fuel and oxidizer create pressure in a combustion chamber.

They both 'burn'  AND 'create pressure'?

In a vacuum?

If you introduce a gas into an evacuated chamber (such as a combustion chamber), then you no longer have a vacuum, do you?

Have you consulted the Laws of Physics on this matter?

Yes, and they agree with me.

Quote from: markjo on November 27, 2015, 01:16:54 PM

In other words, you can't.

No; I can & I did.

If you say so.

Then note the words 'not yet zero...'

Free expansion says that once the system reaches equilibrium, the total work done is zero.  Do you agree with that statement?

Is a rocket engine operating in a vacuum in a state of equilibrium?

When you're trying to explain how motion can be produced in a Vacuum, which is the total absence of all mass, pressure, matter, or any other means of creating friction or resistance, I'd say that every single thing 'matters'.

Again, if you introduce a gas into an evacuated space (such as the combustion chamber of a rocket), then you no longer have a vacuum.

Because such a concept sounds like complete baloney to myself & any other sane person out there...

Incredulity is not a valid argument.

Thus, I will keep grilling you on the details until you give a satisfactory explanation for your claims.

What do you consider a "satisfactory explanation"?

If you introduce a gas into an evacuated chamber (such as a combustion chamber), then you no longer have a vacuum, do you?

When it's open to a practically infinite vacuum?

LOL!!!

Have you consulted the laws of physics on this matter?

Free expansion says that once the system reaches equilibrium, the total work done is zero.  Do you agree with that statement?

I agree you're having difficulty understanding what 'total work done is zero' implies.

Again, if you introduce a gas into an evacuated space (such as the combustion chamber of a rocket), then you no longer have a vacuum.

Again; in a practically infinite vacuum, you are wrong.

Incredulity is not a valid argument

Well you won't accept the laws of physics so I have to try another tack...

What do you consider a "satisfactory explanation"?

Nothing you can offer.

Because 'Nothing' is what we are dealing with here: a total physical vacuum.

And you cannot get Something out of Nothing.

Are you aware a vacuum is not a force?

Quote from: markjo on November 27, 2015, 03:13:45 PM

If you introduce a gas into an evacuated chamber (such as a combustion chamber), then you no longer have a vacuum, do you?

When it's open to a practically infinite vacuum?

If you can introduce the gas into the chamber faster than it can be evacuated, then yes.  Why not?

Have you consulted the laws of physics on this matter?

Yes I have, and they agree with me.

Quote from: markjo on November 27, 2015, 03:13:45 PM

Free expansion says that once the system reaches equilibrium, the total work done is zero.  Do you agree with that statement?

I agree you're having difficulty understanding what 'total work done is zero' implies.

Then explain it to me.  Please.  I especially want to hear about the part where the process of introducing gas in a vacuum considered a state of equilibrium.

Quote from: markjo on November 27, 2015, 03:13:45 PM

Incredulity is not a valid argument

Well you won't accept the laws of physics so I have to try another tack...

I accept the laws of physics.  It's your misinterpretation of those laws of physics that I have a problem with.

Quote from: markjo on November 27, 2015, 03:13:45 PM

What do you consider a "satisfactory explanation"?

Nothing you can offer.

Because 'Nothing' is what we are dealing with here: a total physical vacuum.

Have you never heard the expression "nature abhors a vacuum"?

If you introduce gas to an evacuated combustion chamber, it will expand to fill that void before it escapes through the throat of the nozzle.

And you cannot get Something out of Nothing.

Have you never heard of vacuum energy?
https://en.wikipedia.org/wiki/Vacuum_energy

Are you aware a vacuum is not a force?

LOL!!!

Think about what you just wrote...

Quote from: sokarul on November 27, 2015, 05:03:09 PM

Are you aware a vacuum is not a force?

LOL!!!

Think about what you just wrote...

A vacuum is not a force. You seem to think a vacuum can pull on objects.

If you can introduce the gas into the chamber faster than it can be evacuated, then yes.

Good luck doing that!

Quote from: Papa Legba on November 27, 2015, 04:35:04 PM

Have you consulted the laws of physics on this matter?

Yes I have, and they agree with me.

If that is so, I suggest that several of them did not wish to speak to you, for fear of being abused.

I do not blame them.

Quote from: Papa Legba on November 27, 2015, 04:35:04 PM

Quote from: markjo on November 27, 2015, 03:13:45 PM

Free expansion says that once the system reaches equilibrium, the total work done is zero.  Do you agree with that statement?

I agree you're having difficulty understanding what 'total work done is zero' implies.

Then explain it to me.  Please. 

Nope; it's self-explanatory to anyone with a brain.

I'm not indulging those without any more...

I accept the laws of physics.

Evidence suggests otherwise...

Have you never heard the expression "nature abhors a vacuum"?

Yes & I have mentioned it on this thread already.

You should ponder its implications rather than just trying to sound clever with it.

If you introduce gas to an evacuated combustion chamber, it will expand to fill that void before it escapes through the throat of the nozzle.

No; it would leave via the path of least resistance, i.e. directly through the nozzle.

Unlike yourself, I am still on speaking terms with the laws of physics.

Have you never heard of vacuum energy?

That's the markjo we all know & love!

When on the spot, retreat into theoretical irrelevancies...

A vacuum is not a force.

Still can't work out why that's such a dumb thing to say, can you?

Logic's never been your strong suit has it?

Are there any other things that a vacuum Is Not which you feel you the need to inform me of?

Toodle-pip!

Quote from: markjo on November 27, 2015, 06:17:04 PM

If you can introduce the gas into the chamber faster than it can be evacuated, then yes.

Good luck doing that!

Why should it be that hard?  Large inlets, powerful pumps, propellants that expand quite a lot when burned and a small outlet would be a good start.

Quote from: markjo on November 27, 2015, 06:17:04 PM

Quote from: Papa Legba on November 27, 2015, 04:35:04 PM

Quote from: markjo on November 27, 2015, 03:13:45 PM

Free expansion says that once the system reaches equilibrium, the total work done is zero.  Do you agree with that statement?

I agree you're having difficulty understanding what 'total work done is zero' implies.

Then explain it to me.  Please. 

Nope; it's self-explanatory to anyone with a brain.

Is heat transfer considered work?  If so, then the total work is not zero.

Quote from: markjo on November 27, 2015, 06:17:04 PM

If you introduce gas to an evacuated combustion chamber, it will expand to fill that void before it escapes through the throat of the nozzle.

No; it would leave via the path of least resistance, i.e. directly through the nozzle.

If the combustion chamber is in a vacuum, then there is nothing to resist the gas from expanding to fill the combustion chamber as it makes it way to the nozzle.

Quote from: sokarul on November 27, 2015, 06:25:55 PM

A vacuum is not a force.

Still can't work out why that's such a dumb thing to say, can you?

Logic's never been your strong suit has it?

Are there any other things that a vacuum Is Not which you feel you the need to inform me of?

Toodle-pip!

Just think of how strongly you could destroy me by actually explaining why what I said was dumb. As of now you might as well just give jroa a reach around as you accomplished nothing.

Papa - a vacuum doesn't have some special power where it can suck all the contents out of any container instantaneously. The more you keep spouting the more of a fool you look.

When exposed to a vacuum gas will naturally exit the container when each molecule happens to pass by chance through the exit. If the exit is large then this will happen very quickly, if the exit is rather small then it will take longer. Start actively adding gas at an inlet and it will take longer.

All the time that there is still gas in the container it will exert pressure on the container walls.

A vacuum cannot exert force on objects, it cannot changer their movement. It is just an absence of matter.

Just think of how strongly you could destroy me by actually explaining why what I said was dumb.

I already did explain.

But you were too dumb to notice.

Because your ignorance is the only 'indestructible' thing about you.

Papa - a vacuum doesn't have some special power where it can suck all the contents out of any container instantaneously.

I never said it did.

You, however, do seem to have some special power where you can suck all the context out of my posts instantaneously...

Markjo has already randomly spouted the phrase 'nature abhors a vacuum' without truly pondering its meaning; why don't you all set aside a little pondering time before getting back to me?

Oh, & I haven't read markjo's last post; it's far too early in the day for me to have my brain bent by his convoluted blather, plus it's the weekend.

So if I have by some chance missed a garbage question or two from him, please do not go round trumpeting it as Total Victory for teh raown derf, eh?

Toodle pip, suckers!

Markjo has already randomly spouted the phrase 'nature abhors a vacuum' without truly pondering its meaning; why don't you all set aside a little pondering time before getting back to me?

If the combustion chamber is evacuated, then the gas being introduced to it will try to fill that void, will it not?

Don't worry, we all knew that u're gonna ignore everything that says u're wrong.

After all this is what u've been doing for this entire thread, everytime that someone proves u wrong u just change subject and mangle another part of physics.

Btw rocket will move also if u just open the tanks and let the gas out. Would be extremely inefficient but it will move.

Ps ion engine have already been used.

If the combustion chamber is evacuated, then the gas being introduced to it will try to fill that void, will it not?

I've already answered this, & perfectly correctly too.

Look:

Quote from: markjo on November 27, 2015, 06:17:04 PM

If you introduce gas to an evacuated combustion chamber, it will expand to fill that void before it escapes through the throat of the nozzle.

No; it would leave via the path of least resistance, i.e. directly through the nozzle.

So; why are you asking me the same question again?

The laws of physics will not alter if you harass them, markjo; only the opinions of weak-willed & fearful people do that.

Yet I am neither; who, then, are you in fact aiming your posts at?

Who, markjo?



Enough of your loathsome brainwashing though; let's have a poem!

"How do you know but every Bird that cuts the airy way,

Is an immense world of delight, closed by your senses five?"

Toodle-pip, cultists; do try to expand your horizons beyond sci-fi propaganda & the bestial nightmares invoked by the sleep of reason.

True Humanity, & an immense world of delight, awaits you...

The Door is Open.

The Choice is Yours.

Vieux Legba, ever at the Crossroads...

i really don't see your point... the fuel and oxidizer introduce in the combustion chamber will tend to exit through the nozzle in vaccum... so what? even on the surface since the pressure at which they're injected are much greater than atmospheric pressure.

they won't go istantly outside, they will exit very fast yes but not istantly.
 u just need to have the right mixture and the spark near the injectors to have the combustion
u don't need the entire combustion chamber to be filled with mixture, the gasses produced by the combustion need to have space to expand otherwise u'll and up with an explosion

as long as u can feed propellant at the same rate as it's leaving the combustion chamber u have a continuous combustion.
and yes it's possible since the fuel pumps have thousands of horsepower.

So; why are you asking me the same question again?

Because you seem to be under the impression that the gas being introduced into the combustion chamber is aimed directly at the throat.  This is not the case.  The gas is sprayed in a high pressure mist that expands in all directions.  The vacuum of space doesn't grab the gas and pull it out the back, the gas has to find its way out on its own.

Because you seem to be under the impression that the gas being introduced into the combustion chamber is aimed directly at the throat.

No, I am not.

And I have given you no reason to make that assumption.

This is what I said:

Quote from: markjo on November 27, 2015, 06:17:04 PM

If you introduce gas to an evacuated combustion chamber, it will expand to fill that void before it escapes through the throat of the nozzle.

No; it would leave via the path of least resistance, i.e. directly through the nozzle.

As you can see from the above, I stated that the gas would leave via the path of least resistance.

This would be directly through the nozzle & into the area of lowest pressure, i.e. the enormous zero-pressure vacuum of 'space'.

Why would the gas bounce around inside the combustion chamber, or even fill it, when that is clearly NOT the path of least resistance?

I thought you said you'd consulted the laws of physics on this matter?

Seems I was correct in thinking some of them avoided contact with you for fear of being abused.