HAPPY HOAX ANNIVERSARY!!! (Rockets can't fly in a vacuum)

Quote from: rvlvr on December 22, 2019, 05:06:45 AM

Simple:

That makes zero sense and I find it hard how people can be fooled by it.

Good
Then we'll be happy youre not building anything mechanical.

Or

Lot of complaining from the peanut gallery without any intelligible response.
Why not edit that photo and show/ educate us on what portion of the balloon/ water rocket is being pushed on by the outside compressed gas?

Simple diagram you saw in this thread many times. But you are not smart enough to make sense of it.

Atmosphere is needed only by vehicles that push air backwards. Other types of vehicles push backwards something else and atmosphere is irrelevant. For example, the action and reaction between the wheels and the road will not disappear in vacuum.

Pump is needed to deliver fuel and oxidizer to prevent the pressure inside the chamber to push the gas back into the storages.

If the word "storages" doesn't make sense to you, try the word "tanks", or any other that would describe the places where the fual and the oxidizer are stored before delivery to the combustion chamber.

Gobbledegook.

Quote

Normally, propellant in the tank is stored at a pressure of about 1-4 bar, if the system uses turbopump to deliver high pressure to the combustion chamber. This method reduces the wall thickness and hence the weight of the tank.

(from: https://en.wikipedia.org/wiki/Propellant_tank)

As you can see, without the pumps you couldn't transfer the fuel and the oxidizer from 1-4 bar tanks to 70 bar combustion chamber.

Does that makes sense to you?

EDIT: If rockets were trying to use your operating principle, they wouldn't be able to work.
Luckily, in reality they don't use it.

Is the fuel and oxidizer under pressure before they reach the pumps?

Quote from: sceptimatic on December 22, 2019, 05:07:37 AM

Quote from: rvlvr on December 22, 2019, 05:06:45 AM

Simple:

That makes zero sense and I find it hard how people can be fooled by it.

Good
Then we'll be happy youre not building anything mechanical.

Or

Lot of complaining from the peanut gallery without any intelligible response.
Why not edit that photo and show/ educate us on what portion of the balloon/ water rocket is being pushed on by the outside compressed gas?

Here you go, this is reality.

The combustion chamber is open to the elements so what are you talking about?

This is why I say you should understand the cold gas thruster first.
You clearly have no idea how pressure in gas actually works.
It is not an instant equalisation of pressure.

Yes, the combustion chamber is open to the elements, but it has a pressure gradient across it, being at extremely high pressures at the the throat of the nozzle, and then the pressure decreases as the gas expands to the end of the nozzle.

That makes zero sense and I find it hard how people can be fooled by it.

Again, what part doesn't make sense?
The gas is pushed backwards by the rocket and the rocket is pushed forwards by the gas. A nice simple action-reaction.

The only reason you say it doesn't make sense is because otherwise you would need to admit that rockets work in a vacuum and that kills your fantasy.

Here you go, this is reality.

Are those black lines meant to indicate the force from the skin?
If not, that isn't reality as we are discussing rockets in a vacuum, unless you want to claim the vacuum is pushing back.
Also it can't make sense at all. You have literally nothing pushing the balloon or rocket forwards.
The only force you have on the rocket is pushing backwards, meaning it would need to move backwards.
Meanwhile, you have a greater force on the back of the gas leaving the rocket/balloon which would cause that to go forwards.
So that isn't reality at all. It makes no sense at all for trying to explain what is happening.
Would you like to try again?

Now again, deal with the cold gas thruster.
How does the gas leave when you have clearly indicated that such motion is impossible as there is nothing to push off and no atmosphere?

Quote from: rabinoz on December 22, 2019, 03:52:54 AM

Quote from: sceptimatic on December 22, 2019, 03:19:50 AM

Quote from: JackBlack on December 22, 2019, 03:11:54 AM

Because the combustion chamber is at a higher pressure.

The combustion chamber is open to the elements so what are you talking about?

The "combustion chamber is" NOT "open to the elements so what are you talking about?"

The combustion chamber is separated from "the elements" by the throat and the bell of the nozzle.

No it's not.
It it is then it means it's closed and if it's closed then it's basically a bomb.

If not "open" then the combustion chamber certainly has restricted access to "the elements". And that access is restricted by the throat and the bell part of the nozzle.

Quote from: rabinoz

Is a SCUBA tank "open to the elements" if its tap is broken off.

Yes, obviously.

Your "open" is a very misleading way of describing it.
The ISS had a tiny hole between the inside that was at 14.7 psia and the outside at 0 psia causing a very slow loss of pressure.
An astronaut initially blocked the hole with his finger - yes, his finger!
Astronaut plugged leak in space station with his FINGER before crew used tape to patch up hole caused by a METEORITE
Saying the ISS was "open to the elements" would be totally ridiculous.

Quote from: rabinoz

Sure, the highly compressed air will escape rapidly but not instantly! Look how long it takes:

Torpedo Scuba Tank after valve cut by Timo Dersch

Who's on about instantly?
Is your the rocket acting like a compressed air tank and if so, where's the pump on the compressed air tank?

Yes! The rocket is propelled by exactly same mechanism that makes that SCUBA tank fly around.
The air in the SCUBA tank at 0:21 in the video sends the TANK flying around for about 9 seconds.
But if there were a larger supply of gas it could fly for much longer.

Basically you do not need a pump on a rocket. It's pointless because it cannot do the work of what compressed gas can do when released into the atmosphere.

It certainly is not "pointless" because it is the fuel pump continuously feeds liquid propellant into the combustion chamber which burns providing a continuous supply of gas at a very high pressure.

Quote from: rabinoz

Now imagine a combustion chamber feeding gas continually into that tank at a similar pressure.
The expanding bell is to convert the very high pressure right at the exit to a lower pressure and higher velocity.

Feeding gas into a tank?
Explain this a bit more clearly.

See the above about the fuel pump etc.
If the burnt propellant left the rocket after the throat at a very high temperature, high pressure and velocity it would produce a lot of thrust but a lot of energy would be wasted.
The outside pressure is comparatively low, starting at about 14.7 psia at sea-level and falling to close enough to zero at extreme altitudes.
The pressure of the gas leaving the rocket needs to be no higher than that outside pressure.

The expanding part of the nozzle, the bell part, is to allow the gases to increase in volume and velocity while its pressure and temperature fall.

What matters in generating thrust is the mass and velocity of the propellant expelled.

Quote from: rabinoz

Quote from: sceptimatic

What higher pressure and how is it higher than a release of compressed gas into it and ignited?

The fuel (liquid hydrogen or kerosene ) and oxidiser (liquid oxygen) when burnt make a gas at a very high temperature so in the limited volume of the combustion chamber, are very high pressure.

Yes I get it but it makes zero sense to return that power back into the rocket. The flow is to the exit or nozzle, into the atmosphere.

The energy isn't fo much returned "back into the rocket" but is used to increase the velocity of the exhaust gas and it is the velocity of that exhaust gas that matters.

There's no return pressure to push any rocket in the opposite direction.
If there is then explain this bit in simple terms and don't give me the hogwash that it isn't simple.

You are getting no "hog-wash", though I might be failing to explain things simply enough for you.

But what do you mean by "there's no return pressure to push any rocket in the opposite direction"?

To accelerate a mass, m, to a velocity, v in one second requires a force, F =  m x v - that crucial equation! Just Newton's Second Law of Motion, force = mass x acceleration.

That force is driving the exhaust back out of the rocket and is supplied by an equal and opposite force on the rocket engine, the rocket's thrust.
And note that it is all inside the rocket engine. What is outside has little influence other than to "get in the way" and reduce the effective thrust a little.

Quote from: rabinoz

Quote from: sceptimatic

Why the pump?

To pump the fuel and oxidiser into the high pressure of the combustion chamber.

Is the fuel and oxidizer under tank/container pressure?
Let's use the fictional Saturn V as a yardstick.

The Saturn V certainly is not fictional! Millions saw it in "real life" and billions on "real-time" TV though you might question how it performed.
The fuel (RP-1, basically purified kerosene in the F-1 engines of the Saturn V) and oxidiser (liquid oxygen) tanks are pressurised enough to feed them to the fuel pumps. That is little problem on Earth and while there is thrust being generated but is a problem in "zero-g" between main engine cutoff (MECO) and the ignition of the second stage - but that's for another time.

But the high-pressure fuel and oxidiser pumps needed pump the propellant into the very high pressure in the combustion chamber are huge "beasts" powered by gas turbines that use the same fuel.
Read this if you are really interested, SP-4206 Stages to Saturn: III. Fire, Smoke, and Thunder: The Engines.
The massive fuels pumps and the fuel and oxidiser injector plate design took a great deal of research and experimental work in their development.

Here you go, this is reality.

Thanks.
Can we clarify if we know the difference between force lines and flow of fluid lines?

Quote from: Macarios on December 22, 2019, 05:57:54 AM

Quote

Normally, propellant in the tank is stored at a pressure of about 1-4 bar, if the system uses turbopump to deliver high pressure to the combustion chamber. This method reduces the wall thickness and hence the weight of the tank.

(from: https://en.wikipedia.org/wiki/Propellant_tank)

As you can see, without the pumps you couldn't transfer the fuel and the oxidizer from 1-4 bar tanks to 70 bar combustion chamber.

Does that makes sense to you?

EDIT: If rockets were trying to use your operating principle, they wouldn't be able to work.
Luckily, in reality they don't use it.

Is the fuel and oxidizer under pressure before they reach the pumps?

As you can see already: pressure in storage tanks (area before the pumps) is between 1 and 4 bar.
From that pressure the pumps are transporting it to the chamber where the pressure is 70 bar.
So, ofcourse they are under pressure. It is not vacuum in those tanks.
But that pressure is much lower than the pressure they generate while burning in combustion chamber.
Without the pumps some gas would return from the chamber to the tanks.
It would prevent the intake of more fuel and oxidizer.

Quote from: sceptimatic on December 22, 2019, 11:09:51 AM

Quote from: Macarios on December 22, 2019, 05:57:54 AM

Quote

Normally, propellant in the tank is stored at a pressure of about 1-4 bar, if the system uses turbopump to deliver high pressure to the combustion chamber. This method reduces the wall thickness and hence the weight of the tank.

(from: https://en.wikipedia.org/wiki/Propellant_tank)

As you can see, without the pumps you couldn't transfer the fuel and the oxidizer from 1-4 bar tanks to 70 bar combustion chamber.

Does that makes sense to you?

EDIT: If rockets were trying to use your operating principle, they wouldn't be able to work.
Luckily, in reality they don't use it.

Is the fuel and oxidizer under pressure before they reach the pumps?

As you can see already: pressure in storage tanks (area before the pumps) is between 1 and 4 bar.
From that pressure the pumps are transporting it to the chamber where the pressure is 70 bar.
So, ofcourse they are under pressure. It is not vacuum in those tanks.
But that pressure is much lower than the pressure they generate while burning in combustion chamber.
Without the pumps some gas would return from the chamber to the tanks.
It would prevent the intake of more fuel and oxidizer.

And indeed this is why one of the most complex engineering challenges of any rocket engine (along with stopping it melting) is designing the turbo pumps to feed the combustion chamber.

If not "open" then the combustion chamber certainly has restricted access to "the elements". And that access is restricted by the throat and the bell part of the nozzle.

There's a reason why access is restricted in the throat to the nozzle. It's because the throat harbours the gas and air mix and the nozzle allows the expansion from ignition and burn against the atmosphere.
All the rest of it is basically fictional nonsense set out ot baffle those who are mesmerised by space rockets.

Quote from: sceptimatic

Quote from: rabinoz

Is a SCUBA tank "open to the elements" if its tap is broken off.

Yes, obviously.

Your "open" is a very misleading way of describing it.

No it's not misleading, at all.
Open is open whether it's wide open or partially.

The ISS had a tiny hole between the inside that was at 14.7 psia and the outside at 0 psia causing a very slow loss of pressure.
An astronaut initially blocked the hole with his finger - yes, his finger!
Astronaut plugged leak in space station with his FINGER before crew used tape to patch up hole caused by a METEORITE
Saying the ISS was "open to the elements" would be totally ridiculous.

Look, the ISS is a model.
If that ISS was real and in the space you believe it is it would be near 15 psi against zero external resistance to that pressure.
Basically your ISS would be un able to sustain it's structure.

As for a supposed meteorite hole pinged in it. Why do you people believe all this garbage?
One hole and the Earth is apparently being hit by thousands upon thousands of these meteorites, as we're told....and yet only a stray manages to hit at thousands of mph.
This is the stuff people are coaxed into hanging onto. It bemuses me that most people don't just sit back and listen to the garbage and see it for that........But anyway.

Ohhhh....and if you want to understand what would happen to a container in your so called space....or let's call it an extreme low pressure environment, all you have to do is reverse the process and apply it to a glass thermos that is under low pressure.

You see, the thermos would be your space and the 15 psi would be what's in your supposed ISS.
Now knock the welded nib off the bottom and see how fast that thermos fills with external pressure.
It's almost instant.

That would be your meteorite hole you go on about.

Quote from: sceptimatic

Quote from: rabinoz

Sure, the highly compressed air will escape rapidly but not instantly! Look how long it takes:

Torpedo Scuba Tank after valve cut by Timo Dersch

Who's on about instantly?
Is your the rocket acting like a compressed air tank and if so, where's the pump on the compressed air tank?

Yes! The rocket is propelled by exactly same mechanism that makes that SCUBA tank fly around.
The air in the SCUBA tank at 0:21 in the video sends the TANK flying around for about 9 seconds.
But if there were a larger supply of gas it could fly for much longer.

Yep, it's called compressed air against the atmosphere which is equally compressed by the exiting compressed air as the valve is opened.
This atmospheric pressure is pressurised in the direction of the exiting compressed air and that creates a massive resistance which allows the container to be pushed against that consistent air crash until the pressure becomes less greater than the mass of the container.

There's absolutely nothing inside that container that can push the inside of that container in the opposite direction to it's exiting gas. It's all done external to it.
And it really is simple observation and simple experiment.

Your space rocket is fantasy.

Quote from: sceptimatic

Basically you do not need a pump on a rocket. It's pointless because it cannot do the work of what compressed gas can do when released into the atmosphere.

It certainly is not "pointless" because it is the fuel pump continuously feeds liquid propellant into the combustion chamber which burns providing a continuous supply of gas at a very high pressure.

Why would anyone need a fuel pump on a pressurised container? It makes zero sense.
It's like adding a pump to a compressed air tank and thinking it can somehow pump out more air that the released compression. It's clear and utter nonsense. It really is.

Quote from: sceptimatic

Quote from: rabinoz

Quote from: sceptimatic

What higher pressure and how is it higher than a release of compressed gas into it and ignited?

The fuel (liquid hydrogen or kerosene ) and oxidiser (liquid oxygen) when burnt make a gas at a very high temperature so in the limited volume of the combustion chamber, are very high pressure.

Yes I get it but it makes zero sense to return that power back into the rocket. The flow is to the exit or nozzle, into the atmosphere.

The energy isn't so much returned "back into the rocket" but is used to increase the velocity of the exhaust gas and it is the velocity of that exhaust gas that matters.

Your rocket exits fire. A burn. A burning thrust of compressed gases....in one direction only....into the atmosphere.
The atmosphere is the resistance and the resistance that becomes equally as compressed as the hot gases hitting it which create a perfect gas on gas fight.
The rocket rests on this fight at each millimetre as that gas on gas fight ensues for as long as the rocket expels a burning thrust.

Quote from: sceptimatic

There's no return pressure to push any rocket in the opposite direction.
If there is then explain this bit in simple terms and don't give me the hogwash that it isn't simple.

You are getting no "hog-wash", though I might be failing to explain things simply enough for you.

Maybe go bottom line simple and explain it with simple analogies to show me what's what.

But what do you mean by "there's no return pressure to push any rocket in the opposite direction"?

Atmosphere. Resistance.

To accelerate a mass, m, to a velocity, v in one second requires a force, F =  m x v - that crucial equation! Just Newton's Second Law of Motion, force = mass x acceleration.
That force is driving the exhaust back out of the rocket and is supplied by an equal and opposite force on the rocket engine, the rocket's thrust.

Like I said before, this means nothing unless it's shown why and how it works.
A simple analogy would suffice to show me from your side.

And note that it is all inside the rocket engine. What is outside has little influence other than to "get in the way" and reduce the effective thrust a little.

The absolute whole purpose of the atmosphere is to get in the way .
You use it as some kind of hindrance. It's an absolute necessity...at all times.
 

Quote from: sceptimatic

Quote from: rabinoz

Quote from: sceptimatic

Why the pump?

To pump the fuel and oxidiser into the high pressure of the combustion chamber.

Is the fuel and oxidizer under tank/container pressure?
Let's use the fictional Saturn V as a yardstick.

The Saturn V certainly is not fictional! Millions saw it in "real life" and billions on "real-time" TV though you might question how it performed.
The fuel (RP-1, basically purified kerosene in the F-1 engines of the Saturn V) and oxidiser (liquid oxygen) tanks are pressurised enough to feed them to the fuel pumps. That is little problem on Earth and while there is thrust being generated but is a problem in "zero-g" between main engine cutoff (MECO) and the ignition of the second stage - but that's for another time.

Yeah, let's not add to the issue.

But the high-pressure fuel and oxidiser pumps needed pump the propellant into the very high pressure in the combustion chamber are huge "beasts" powered by gas turbines that use the same fuel.
Read this if you are really interested, SP-4206 Stages to Saturn: III. Fire, Smoke, and Thunder: The Engines.
The massive fuels pumps and the fuel and oxidiser injector plate design took a great deal of research and experimental work in their development.

How about you tell me how much fuel each engine uses per second and then tell me the diameter of pipes from the pump and also the combustion chamber jet holes as well as the chamber itself.

Let's see if they marry up to not only hold that amount of fuel but to actually burn it inside the rocket.
You seem keen to show me the f/ma and what not so let's see you describe this.

And by the way I can't find and sizes relating to this, before you ask.

Quote from: sceptimatic on December 22, 2019, 11:09:51 AM

Quote from: Macarios on December 22, 2019, 05:57:54 AM

Quote

Normally, propellant in the tank is stored at a pressure of about 1-4 bar, if the system uses turbopump to deliver high pressure to the combustion chamber. This method reduces the wall thickness and hence the weight of the tank.

(from: https://en.wikipedia.org/wiki/Propellant_tank)

As you can see, without the pumps you couldn't transfer the fuel and the oxidizer from 1-4 bar tanks to 70 bar combustion chamber.

Does that makes sense to you?

EDIT: If rockets were trying to use your operating principle, they wouldn't be able to work.
Luckily, in reality they don't use it.

Is the fuel and oxidizer under pressure before they reach the pumps?

As you can see already: pressure in storage tanks (area before the pumps) is between 1 and 4 bar.
From that pressure the pumps are transporting it to the chamber where the pressure is 70 bar.
So, ofcourse they are under pressure. It is not vacuum in those tanks.
But that pressure is much lower than the pressure they generate while burning in combustion chamber.
Without the pumps some gas would return from the chamber to the tanks.
It would prevent the intake of more fuel and oxidizer.

Let's make this simple.
Your supposed space rocket is upright.
It's supposedly holding pressurised tanks.
Pumps cannot make the flow any faster coming from those pressurised tanks.
If you want to argue tanks that are not pressurised, such as kerosene then that kerosene would need to be stored in massive tanks and fed down to the nozzle for burn, along with a propellent or oxidiser.
A pump would not be needed.

How about you cut out all the junk and explain why a pump is needed.

Quote from: Macarios on December 22, 2019, 06:22:52 PM

Quote from: sceptimatic on December 22, 2019, 11:09:51 AM

Quote from: Macarios on December 22, 2019, 05:57:54 AM

Quote

Normally, propellant in the tank is stored at a pressure of about 1-4 bar, if the system uses turbopump to deliver high pressure to the combustion chamber. This method reduces the wall thickness and hence the weight of the tank.

(from: https://en.wikipedia.org/wiki/Propellant_tank)

As you can see, without the pumps you couldn't transfer the fuel and the oxidizer from 1-4 bar tanks to 70 bar combustion chamber.

Does that makes sense to you?

EDIT: If rockets were trying to use your operating principle, they wouldn't be able to work.
Luckily, in reality they don't use it.

Is the fuel and oxidizer under pressure before they reach the pumps?

As you can see already: pressure in storage tanks (area before the pumps) is between 1 and 4 bar.
From that pressure the pumps are transporting it to the chamber where the pressure is 70 bar.
So, ofcourse they are under pressure. It is not vacuum in those tanks.
But that pressure is much lower than the pressure they generate while burning in combustion chamber.
Without the pumps some gas would return from the chamber to the tanks.
It would prevent the intake of more fuel and oxidizer.

And indeed this is why one of the most complex engineering challenges of any rocket engine (along with stopping it melting) is designing the turbo pumps to feed the combustion chamber.

Tell me how a turbo pump works inside a rocket.
We know how they work on trucks and stuff, so tell me about this on a so called space rocket that somehow manages to super pump this fuel into a chamber faster than a compressed tank can release it.

Quote from: rabinoz on December 22, 2019, 03:05:09 PM

If not "open" then the combustion chamber certainly has restricted access to "the elements". And that access is restricted by the throat and the bell part of the nozzle.

There's a reason why access is restricted in the throat to the nozzle. It's because the throat harbours the gas and air mix and the nozzle allows the expansion from ignition and burn against the atmosphere.
All the rest of it is basically fictional nonsense set out ot baffle those who are mesmerised by space rockets.

You are trying to twist the reality again.

The fuel-oxidizer mix starts burning in the combustion chamber before it reaches the nozzle.
That is the purpose of the oxidizer in the first place.
To provide oxygen for fuel burning where there is no atmosphere to get it from.

One of the common liquid fuel mixture is methane and oxygen.

One CH4 molecule needs two O2 molecules to make one CO2 molecule and two H2O molecules.
Both methane and oxygen are pumped from tanks, atmosphere is excluded completely.
Both CO2 and H2O are getting pressurized by the burnng and get pushed with high energy through the nozzle,
together with the small quantity of not yet burned remains of the CH4 and O2 that finish burning outside.

Pumps CAN transfer fuel and oxidizer from 1-4 bar to 70 bar the same way as water pumps can transfer water upwards from rivers and lakes to water towers and other reservoirs. You don't need upward pressure of river water to make pump push it up.

When exhaust exits the rocket its involvement in the pushing process is over.
The atmosphere outside is not returning the exhaust back to push the rocket more.
That is why the existence of the atmosphere is irrelevant.
The next portion of the exhaust keeps pushing the rocket further, not the portion that is out already.

allows the expansion from ignition and burn against the atmosphere.

You are yet to provide any sort of rational explanation as to why it needs to push against the atmosphere or how it achieves that.
The actual reason is to provide the maximal thrust
You not liking something because it shows you are wrong doesn't make it nonsense.

Basically your ISS would be un able to sustain it's structure.

Why? that is just another pathetic assertion from you.
What makes you say it can't sustain its structure?
Is it because you need to grasp at whatever BS you can to reject reality so you can cling to your FE fantasy?

Ohhhh....and if you want to understand what would happen to a container in your so called space....or let's call it an extreme low pressure environment, all you have to do is reverse the process and apply it to a glass thermos that is under low pressure.

No, you don't. That doesn't help at all. We have been over this plenty of times already.
Crushing a container is quite different to blowing it up.
All you need to see that is a simple plastic drinking bottle.
First suck in all the air and you easily collapse the bottle.
Try try to burst the bottle and you will find no matter how hard you push, you can't.
You can even attach a pressure gauge to it and see what pressure it can take.
You will find it is far more resistant to higher pressures inside than higher pressures outside.

Now knock the welded nib off the bottom and see how fast that thermos fills with external pressure.
It's almost instant.

Because it is a tiny volume with a large hole.
Amazingly enough, size and scale is important.
A key thing to note is that the volume scales with length cubed, while the area scales with length squared.
What that means is that as a first approximation if you simply scale up the object such that a linear dimension is doubled, the volume will be multiplied by 8 and the area by 4. That means the flow rate of the gas will be multiplied by 4 while the volume it needs to fill is multiplied by 8, making it take twice as long.

Your space rocket is fantasy.

Then provide a viable alternative. Explain what is happening with the cold gas thruster. Because so far the only options are either rockets work in space, or pure nonsense.

Why would anyone need a fuel pump on a pressurised container? It makes zero sense.

It only makes 0 sense when you ignore the explanations which have already been provided.
But like I said, deal with a cold gas thruster first, then move on to more complex issues.

We know how they work on trucks and stuff, so tell me about this on a so called space rocket that somehow manages to super pump this fuel into a chamber faster than a compressed tank can release it.

You are aware it is the exact same principle, but different scales?
If it makes no sense for a rocket, it makes no sense for a truck.
If it makes sense for a truck, it makes sense for a rocket.

A burning thrust of compressed gases....in one direction only....into the atmosphere.

In one direction only, because that is the direction the rocket has pushed it into, with a resulting reaction pushing the rocket in the other direction.
No need for the atmosphere.
The gas provides the resistance.

A simple analogy would suffice to show me from your side.

Except such analogies have already been provided and you just ignore them.

Let's make this simple.

I have already made it extremely simple for you, yet you still fail to address the issue and provide a viable alternative to the reality of rockets working in space.

Again, you have a simple tube open at one end with pressurised gas inside. What happens?
Does the gas stay put? If so, what is keeping it there?
If not, then what is it pushing against to move as you have clearly indicated that you believe there is nothing for it to push off and such motion would require the atmosphere.

Until you can actually address this extremely simple case you have absolutely no basis to claim rockets cannot work in space.

So tell us, either how the gas magically stays inside an open container, or what it is pushing off which doesn't allow the rocket to work.

Quote from: rabinoz on December 22, 2019, 03:05:09 PM

The ISS had a tiny hole between the inside that was at 14.7 psia and the outside at 0 psia causing a very slow loss of pressure.
An astronaut initially blocked the hole with his finger - yes, his finger!
Astronaut plugged leak in space station with his FINGER before crew used tape to patch up hole caused by a METEORITE
Saying the ISS was "open to the elements" would be totally ridiculous.

Look, the ISS is a model.

Incorrect! The ISS has been proven numerous times to appear exactly when and where it's been predicted.
It's been photographed numerous times with telescopic showing it looks exactly as it should and a few times simultaneously from different location enabling it's altitude and distance to be to be determined.

You deny the ISS simply because it doesn't fit with your believe and not because you've any evidence.

If that ISS was real and in the space you believe it is it would be near 15 psi against zero external resistance to that pressure.
Basically your ISS would be un able to sustain it's structure.

Rubbish! The structure of the ISS has been designed to withstand that stress.
An "ISO Tank Container" is designed to fit the space of a standard 40' ISO shipping container and has a similar diameter to the ISS is tested at 6 Bar, i.e. 6 x normal atmospheric pressure.

The most common type of tank is UN type T11 which can carry more than 1000 types of dangerous goods. T11 tanks are the most common tank in use, tested to 6 bars of pressure and have a working pressure of 4 bar. (Qualitank keep a number of tanks available which have current valid test certificates.)

This sort of thing:

So why do you find it hard to believe that the ISS cannot withstand an internal pressure of only 14.7 psia?

There's nothing magic about a vacuum - as far as stresses are concerned it's nothing more than a region of almost zero pressure.
A similar sized structure on earth with an internal pressure ot 29.4 psi would be subject to the same stresses.

As for a supposed meteorite hole pinged in it. Why do you people believe all this garbage?

Possibly because it is not garbage but is quite true?

One hole and the Earth is apparently being hit by thousands upon thousands of these meteorites, as we're told....and yet only a stray manages to hit at thousands of mph.

Sure, "the Earth is apparently being hit by thousands upon thousands of these meteorites" but the earth has an area of 510.1 million km² and the ISS has an area of less than ¹/₁₀₀₀ of a square kilometre! That's an area ratio of some 500 billion.

But who says "only a stray manages to hit at thousands of mph." All that was said is that micro meteorite caused a tiny hole. The ISS has, in fact, been hit numerous times with damage to solar panels etc.

But the pressurised section of the ISS is largely protected with shields like this:

The modules of the ISS are protected by Whipple shields: basically an extra wall outside the main pressure hull. A micrometeorite would puncture this shield and disintegrate, leaving nothing big enough to penetrate the main hull. In this image, the shield is on the right:

This is the stuff people are coaxed into hanging onto. It bemuses me that most people don't just sit back and listen to the garbage and see it for that........But anyway.

Just possibly those people know enough and understand enough to realise that it is all quite feasible.

Ohhhh....and if you want to understand what would happen to a container in your so called space....or let's call it an extreme low pressure environment, all you have to do is reverse the process and apply it to a glass thermos that is under low pressure.

You see, the thermos would be your space and the 15 psi would be what's in your supposed ISS.
Now knock the welded nib off the bottom and see how fast that thermos fills with external pressure.
It's almost instant.

That would be your micro-meteorite hole you go on about.

Sure BUT:!
The volume of that evacuated space in the Thermos would be around 200 ml or 0.0002 m³ and
the pressurised volume of the ISS is 915.5 m³ - you do the sums!

Your arguments are nothing more that attempts to ridicule and it doesn't work! Try to fool someone more gullible!

Quote from: sceptimatic on December 22, 2019, 11:21:49 AM

Here you go, this is reality.

Thanks.
Can we clarify if we know the difference between force lines and flow of fluid lines?

Scepti is distracting you all away from this diagram that shows zero motion!
This technical mumbojumbo is all a distractioon when he cant even explain away the medicine ball or a balloon or a water rocket - the basic premise of his argument - that ejecting mass will cause a body to move in opposite direction and does not reuqire atmosphere to "springboard a gas-on-gas fight".

Hes provided a picture with no net forward force that would result in water rocket motion.
He failed to show where the water is, or its function.
It is nonsense.

Quote from: sceptimatic on December 23, 2019, 12:26:43 AM

Basically your ISS would be un able to sustain it's structure.

Why? that is just another pathetic assertion from you.
What makes you say it can't sustain its structure?
Is it because you need to grasp at whatever BS you can to reject reality so you can cling to your FE fantasy?

Come back to me when you're more civil.

Rockets can fly in a vacuum.

Here is a (specifically) beginner's guide to how that works.

Quote from: rvlvr on December 22, 2019, 05:06:45 AM

Simple:

That makes zero sense and I find it hard how people can be fooled by it.

Balloon top right has an internal left and a force that is unbalanced internal right that is able to escape out the opening.
Net directional motion to the left.

In your version, you were asked to show what part of the rocket is pushed on by the outside expanding gas on gas figt.

Still yet to see.

I posted a message a while ago(#2372) and was totally ignored. I am curious as to why.  I took what I thought was a Zetetic approach which I thought was the preferred method.  Most of the people explain very well why a rocket can work in a vacuum.  I thought I would relay things I actually saw and did.  So I would be interested in why there were no responses to my post. 

Come back to me when you're more civil.

I have been civil.
You are the one continually being uncivil by your repeated accusations of us all being brainwashed fools incapable of thinking and you repeatedly ignoring what has being said and/or dismissing it as hog-wash or the like.
You are in no place to complain about people allegedly being uncivil.

Calling you out on your repeated baseless assertions is not being uncivil. If you don't want me to call you out on them then either stop making them or actually back them up. So far it seems all you have done on this thread is repeatedly claim that rockets can't work in space, yet provided absolutely no justification for it, no problem with the explanations for how they work, no viable alternative, and just a bunch of insults and distractions.

Now how about you leave us all and come back when you have a coherent model which can actually explain such a simple issue.
Again, you have a simple tube open at one end with pressurised gas inside. What happens?
Does the gas stay put? If so, what is keeping it there?
If not, then what is it pushing against to move as you have clearly indicated that you believe there is nothing for it to push off and such motion would require the atmosphere?
If the gas can move it entirely refutes your argument about rockets allegedly not working in space.

How about addressing the failure of your image to explain anything.
Again:
Are those black lines meant to indicate the force from the skin?
If not, that isn't reality as we are discussing rockets in a vacuum, unless you want to claim the vacuum is pushing back.
Also it can't make sense at all. You have literally nothing pushing the balloon or rocket forwards.
The only force you have on the rocket is pushing backwards, meaning it would need to move backwards.
Meanwhile, you have a greater force on the back of the gas leaving the rocket/balloon which would cause that to go forwards.
So that isn't reality at all. It makes no sense at all for trying to explain what is happening.
Would you like to try again?

Until you can address both of these, providing a viable alternative explanation for how a rocket works in the atmosphere and providing a viable explanation for how the gas leaves while magically not allowing the rocket to move you have literally no basis for your claim that rockets cannot work in a vacuum or that an atmosphere is needed for motion.
Both of these completely destroy your false ideas.

Quote from: JackBlack on December 23, 2019, 03:34:10 AM

Quote from: sceptimatic on December 23, 2019, 12:26:43 AM

Basically your ISS would be un able to sustain it's structure.

Why? that is just another pathetic assertion from you.
What makes you say it can't sustain its structure?
Is it because you need to grasp at whatever BS you can to reject reality so you can cling to your FE fantasy?

Come back to me when you're more civil.

You come back when you are prepared to face reality.

Once again Sceptimatic shows that he doesn’t understand the difference between compression and tensile stress on a cylinder.

A cylinder is at least an order of magnitude stronger in tensile vs compression.

Rubbish! The structure of the ISS has been designed to withstand that stress.
An "ISO Tank Container" is designed to fit the space of a standard 40' ISO shipping container and has a similar diameter to the ISS is tested at 6 Bar, i.e. 6 x normal atmospheric pressure.

Quote

The most common type of tank is UN type T11 which can carry more than 1000 types of dangerous goods. T11 tanks are the most common tank in use, tested to 6 bars of pressure and have a working pressure of 4 bar. (Qualitank keep a number of tanks available which have current valid test certificates.)

This sort of thing:

So why do you find it hard to believe that the ISS cannot withstand an internal pressure of only 14.7 psia?

There's nothing magic about a vacuum - as far as stresses are concerned it's nothing more than a region of almost zero pressure.
A similar sized structure on earth with an internal pressure ot 29.4 psi would be subject to the same stresses.

Are you saying this tank is what holds the fuel in a rocket?
Or is this tank far too small to be a tank for the saturn V?

How big would the saturn V tank be to hold the pressure?

Your rocket is not getting off the ground.
As for the so called ISS, are you saying this tank is the skin of it?

Rockets can fly in a vacuum.

Here is a (specifically) beginner's guide to how that works.

And you think that solves the issue?
Read the topic and absorb it and come back with something better.

I have been civil.

No you haven't.

You come back when you are prepared to face reality.

It won't be the pretend one you adhere to, that's for absolute certain.

Once again Sceptimatic shows that he doesn’t understand the difference between compression and tensile stress on a cylinder.

A cylinder is at least an order of magnitude stronger in tensile vs compression.

Do you even know what you're saying?
Quote where you think I don't know.

Quote from: sceptimatic on December 22, 2019, 05:07:37 AM

Quote from: rvlvr on December 22, 2019, 05:06:45 AM

Simple:

That makes zero sense and I find it hard how people can be fooled by it.

Balloon top right has an internal left and a force that is unbalanced internal right that is able to escape out the opening.
Net directional motion to the left.

In your version, you were asked to show what part of the rocket is pushed on by the outside expanding gas on gas figt.

Still yet to see.

Forget everyone else, scepti.
Your rocket diagram fails to show what exactly is pushing on the rocket
All you have is your gasongas fight and results in no motion.

And the balloon diagram.
Yoy have no net directional force on the balloon to cause it to move.

has a similar diameter to the ISS is tested at 6 Bar, i.e. 6 x normal atmospheric pressure.
[/quote]Are you saying this tank is what holds the fuel in a rocket?
Or is this tank far too small to be a tank for the saturn V?
[/quote]
Not good at reading are you?
He is saying nothing about the Saturn V. He is discussing the ISS.

Read the topic and absorb it and come back with something better.

Good advice, you should try following it.
Go and actually read the thread and absorb what has been said. Look at all the arguments presented for why rockets MUST work in a vacuum, and then only come back when you can actually refute those arguments, such as explaining what the gas is magically pushing off to allow it to move but not the rocket.

Do you even know what you're saying?
Quote where you think I don't know.

I'm pretty sure he does, just like others have already shown.

There are 2 main ways you can stress a cylinder (or any object for that matter).
One is by placing a force on the outside pushing inwards. This is called compression.
The other is by placing a force in the inside pushing outwards. This is called tension.
The ability for objects to withstand these forces without failing are vastly different.
For an object under compression it can buckle and deform.
For an object under tension it needs to actually break apart the structure.
This means if you have a hollow object like a cylinder it will be much stronger under tension than compression.

Again, I already provided you with an example of how you can confirm this, but in your typical uncivil way, you just completely ignore whatever shows you are wrong.

Now again, care to explain how the gas can move when you claim such motion is impossible without the atmosphere and how it can move when you claim there is nothing for it to push off?
If it can move that shows that you don't need the atmosphere to do so and that either there is something in space for it to push off (such as the rocket) or you don't need something to push off. Either way, rockets work.

The only way to not have rockets work in a vacuum is to claim that the gas remains inside the rocket. But then you don't have the gas leaving the rocket so it is back to pushing outwards in all directions, in which case it is pushing the rocket forwards and again rockets need to work.


And with your diagrams you are yet to show one which either shows how the gas leaves in a vacuum or how the rocket moves in the air. You have no lines of force pushing your rocket forwards and have completely unbalanced (i.e. no reactionary forces) lines of force acting on your gas.

In short, like always you have no explanation.

But I expect you will just ignore this yet again.