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Thread: Rockets need an atmosphere to propel. There's no air in space.

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    Rockets need an atmosphere to propel. There's no air in space.

    Rockets needs an external resistance to push off of and there is no such resistance in space. There is no equal and opposite reaction from gas movement due to pressure gradient force. For those who think they know all about Newton's 3rd law, watch this first before commenting. https://www.youtube.com/watch?v=AubI...ature=youtu.be

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    No, you don't need anything to push off from. When you throw something one way you have to go the other. Clearly air resistance would not be strong enough to cause recoil from a gun--just think of the tiny size of bullet and how its pointed head goes through the air.

    But why is this a conspiracy?
    As above, so below

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    To be fair, this is a misconception with an historic and illustrious pedigree...
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    Gee, if only it were possible to create a vacuum here on earth (hmmmm......possibly in some sort of "chamber"? Eh?), then we would actually be able to perform a simple test on this! And, if such mythical "vacuum chambers" were cheap enough to build that schools and universities could have access to them then we would have literally MILLIONS of people on Earth with first hand experience of whether or not rockets work in a vacuum. Tell me, do you think we live in such a world?

    But alas, it's just not possible for anybody to remove the air from a chamber to actually test this first hand. Right rockethunter? You think it hasn't been possible to easily create a vacuum chamber here on Earth for the past few centuries? And thus no modern scientist or engineer could ever actually test this, so instead we have to wait for some random internet person to have the idea to say "HEY!! You know those things we've been using in space for the past 60 years? Maybe somebody should test if they work or not......."

    Sarcasm aside, I am genuinely curious if it even occurred to you before right now that we can test this using vacuum chambers here on earth so easily that YOU could perform this experiment yourself in your own backyard with only a minimal investment of time and materials. Did you think nobody before you had ever thought to do this? Seriously?

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    Quote Originally Posted by rockethunter View Post
    Rockets needs an external resistance to push off of and there is no such resistance in space. There is no equal and opposite reaction from gas movement due to pressure gradient force. For those who think they know all about Newton's 3rd law, watch this first before commenting. https://www.youtube.com/watch?v=AubI...ature=youtu.be
    What complete willfully ignorant individual, and I put you into the same category since you posted nonsense without really researching the notion. There is exactly an equal and opposite reaction in a rocket engine and it has nothing to do with the atmosphere. The reaction is pushing against the engine pushing it in the opposite direction that the exhaust.

    Here is another YT video that disproves the OP have fun watching and perhaps learning a bit.

    https://www.youtube.com/watch?v=GxBRQXxBRic

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    Quote Originally Posted by rockethunter View Post
    Rockets needs an external resistance to push off of and there is no such resistance in space. There is no equal and opposite reaction from gas movement due to pressure gradient force. For those who think they know all about Newton's 3rd law, watch this first before commenting. https://www.youtube.com/watch?v=AubI...ature=youtu.be
    rockethunter

    First, welcome to CQ. I hope you have reviewed our rules, particularly as they apply to the Conspiracy Theory (CT) forum (link in my signature).

    Second, as the advocate of such a non-mainstream idea, you are required to answer all questions put to you in this thread and to present evidence to support your case. And your evidence needs to be more than posting links to Youtube videos. You can reference such videos, but you must explain what they contain and their significance in your own words.

    Have fun.
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    Quote Originally Posted by bknight View Post
    What complete willfully ignorant individual, and I put you into the same category since you posted nonsense without really researching the notion.
    Please, let's keep this polite.
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    As I said in the other thread, the very first slide of your video shows that when you throw a basketball away while on rollerskates, you tend to roll backwards. That's how rockets work! You throw ( = accelerate) mass in one direction, and you experience a force in the opposite direction.

    You roll backwards because you throw away (=accelerate) the mass of the basketball, not because you push it against the air as if it were a wall. If that were the case, you'd still roll backwards if you'd throw away the ball really slowly, but you don't! The force you feel is the mass you throw times its acceleration. If you throw the basketball slowly, you feel only very little force. Throw it fast, and you'll feel enough force that you might start to roll backwards. Also if you'd do that in a vacuum.

    Rockets don't throw basketballs out of their engines obviously, but the burnt fuel. It is accelerated enormously, such that even the relatively low mass of the fuel (they burn many tons of it in a short amount of time though!) still results in a large force.

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    That YouTube narrator ought to go soak her head in a bucket of soapy water. She is giving us a slick, sugar-coated presentation in which she is glossing over some key details which would refute her if we take the time to work out the analysis thoroughly. Unfortunately that probably will take more work than she did in preparing the video.

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    Proof by Youtube video

    This guy set-up a model rocket engine in a vacuum chamber he fabricated. His intent seems to be mostly to counter an apparent belief that rockets don't work in vacuum because there is no air for combustion. But it also nicely demonstrates you can get thrust in a vacuum without air to push against. Watch the video at about the 2:25 mark; when the rocket starts you can see it move - swinging forward from the frame it is hanging from.
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    Apart from the explanation of how it does work above, you can also test the validity of a conspiracy theory by thinking about what it would take to test it. The claim is that Newton's third law (accelerate a mass in one direction results in a force in the other direction) does not work in a vacuum. To test this, you'd need an object capable of accelerating (expelling, throwing) a mass in a container that is sucked vacuum. Not that hard eh? You can buy or make a glass or otherwise transparent vacuum chamber easily enough. Then you'd need an object expelling a mass while in the vacuum chamber. Think along the lines of a toy car with a ball and tensioned spring, and a way to release that spring from outside the vacuum chamber. Could be a remote control servo if you want to go fancy, but you can also imagine even easier solutions (a holding pin with a string and magnet or something). Cart shoots ball in one direction, car runs in other direction. Conspiracy theory disproven.

    The tests shown in that video are not relevant or done in a very imprecise way. The whole thing about dropping something and not feeling force is irrelevant: when you drop something, you don't accelerate it so you don't feel anything. Gravity accelerates it. See the difference with the "throw a basketball on roller skates" example. The balloon and vacuum cleaner example goes wrong in so many ways: way too large aerodynamic forces compared to Newtonian forces, wrong direction of air acceleration. Stop the half-baked tests, do one serious test in a vacuum chamber, and you have your answer.

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    Quote Originally Posted by Swift View Post
    Proof by Youtube video

    This guy set-up a model rocket engine in a vacuum chamber he fabricated. His intent seems to be mostly to counter an apparent belief that rockets don't work in vacuum because there is no air for combustion. But it also nicely demonstrates you can get thrust in a vacuum without air to push against. Watch the video at about the 2:25 mark; when the rocket starts you can see it move - swinging forward from the frame it is hanging from.
    Here they shoot a gun in a vacuum, and guess what: recoil.

    https://www.youtube.com/watch?v=KH7mNApnDYg

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    Second video from the same guy
    This time with a solid rocket fuel motor instead of black powder, and he actually has a scale to measure the trust. Took a couple of attempts to get everything to work. Successful demo starts at about the 10 minute mark.
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    Quote Originally Posted by rockethunter View Post
    Rockets needs an external resistance to push off of and there is no such resistance in space. There is no equal and opposite reaction from gas movement due to pressure gradient force. For those who think they know all about Newton's 3rd law, watch this first before commenting. https://www.youtube.com/watch?v=AubI...ature=youtu.be
    No reaction from pressure gradient force? That directly contradicts Newton's Third Law. If there is a force, there is a reaction to it.

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    Quote Originally Posted by rockethunter View Post
    Rockets needs an external resistance to push off of and there is no such resistance in space. There is no equal and opposite reaction from gas movement due to pressure gradient force. For those who think they know all about Newton's 3rd law, watch this first before commenting. https://www.youtube.com/watch?v=AubI...ature=youtu.be
    Rockethunter, you link a youtube video that claims that some forces do not follow Newton's 3rd law. This is not accurate: as near as we can tell, momentum cannot be created or destroyed. That seems to be the underlying confusion that results in the video author's opinion that rocket's won't work in a vacuum.

    Here's a question for you... if an operating rocket were lifted from sea level up to the vacuum of space, in your model would the thrust slowly decay as ambient pressure dropped or would it stop thrusting suddenly at a certain pressure?

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    Quote Originally Posted by Swift View Post
    Proof by Youtube video

    This guy set-up a model rocket engine in a vacuum chamber he fabricated. His intent seems to be mostly to counter an apparent belief that rockets don't work in vacuum because there is no air for combustion. But it also nicely demonstrates you can get thrust in a vacuum without air to push against. Watch the video at about the 2:25 mark; when the rocket starts you can see it move - swinging forward from the frame it is hanging from.
    Yes the same video I linked earlier.

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    Quote Originally Posted by bknight View Post
    What complete willfully ignorant individual, and I put you into the same category since you posted nonsense without really researching the notion. There is exactly an equal and opposite reaction in a rocket engine and it has nothing to do with the atmosphere. The reaction is pushing against the engine pushing it in the opposite direction that the exhaust.

    Here is another YT video that disproves the OP have fun watching and perhaps learning a bit.

    https://www.youtube.com/watch?v=GxBRQXxBRic
    The chamber fills up with gas instantly when the rocket is ignited. When you can see smoke, the pressure is greater than atmospheric. The experiment fails because the chamber fails to maintain vacuum. Vacuum=absence of matter. Smoke = matter.

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    I believe I have experimented to my satisfaction. There is no other proof, other than NASA fake video footage, of rockets working in a vacuum.

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    I does decay. In every rocket launch video you can see this decay as the rocket starts to move sideways.

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    Quote Originally Posted by Glom View Post
    No reaction from pressure gradient force? That directly contradicts Newton's Third Law. If there is a force, there is a reaction to it.
    Do you have any proof of this? When I dead lift 100kg (I am 75kg) and I drop it from a height, do I get lifted off the ground. Because that is basically what you are saying.

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    Quote Originally Posted by rockethunter View Post
    The chamber fills up with gas instantly when the rocket is ignited. When you can see smoke, the pressure is greater than atmospheric. The experiment fails because the chamber fails to maintain vacuum. Vacuum=absence of matter. Smoke = matter.
    Clearly you did not watch the video all the way through. At the end he demonstrates that after the test the vacuum is still present.

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    Quote Originally Posted by rockethunter View Post
    I believe I have experimented to my satisfaction. There is no other proof, other than NASA fake video footage, of rockets working in a vacuum.
    Exactly what experimentation have you done? Please list all of them and what measurements you took.

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    Quote Originally Posted by bknight View Post
    Exactly what experimentation have you done? Please list all of them and what measurements you took.
    Experiments in here show no opposite reaction due to gas movement due to pressure differential. At the end of the video, the NASA thrust equation if invalidated.

    https://www.youtube.com/watch?v=AubIFUsq7Ss




    Here is another independent video.

    https://www.youtube.com/watch?v=D-v_K1k8Se0

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    Quote Originally Posted by Swift View Post
    Proof by Youtube video

    This guy set-up a model rocket engine in a vacuum chamber he fabricated. His intent seems to be mostly to counter an apparent belief that rockets don't work in vacuum because there is no air for combustion. But it also nicely demonstrates you can get thrust in a vacuum without air to push against. Watch the video at about the 2:25 mark; when the rocket starts you can see it move - swinging forward from the frame it is hanging from.
    At the 2:26 mark it blows of a solid chunk off (seems to be some sort of casing) and then you can see the smoke. A rocket in space doesn't blow off a solid chunk nor does it pressurize space.

    The pressure pushed off the solid chunk and in turn pushed off the rocket. Like firing a gun, yes there is recoil because pressure builds up between the gun and bullet. The pressure pushes the bullet out and in turn pushes the gun. A rocket is like a gun firing a blank. The powder burns and moves out of the barrel only pushing off the air (assuming the gun powder was not encased in anything). Now if there was no solid chunk blown off, there wouldn't have been movement until the chamber pressurized. But even that is hard to tell because it pressurized instantly.

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    Quote Originally Posted by bknight View Post
    Clearly you did not watch the video all the way through. At the end he demonstrates that after the test the vacuum is still present.
    At the end vacuum is present? Even with all that smoke visible? He opened the chamber and you could see the smoke come out

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    Quote Originally Posted by rockethunter View Post
    The chamber fills up with gas instantly when the rocket is ignited....
    That is wrong, rockethunter. The chamber starts with no gas in it (that is a vacuum). The rocket ignites and gas starts to fill the space behind it. Meanwhile the rocket has obeyed Newton's third law and moved away from the gas.

    A later post has "NASA fake video footage" ignorance. Spacecraft in space are moved by rockets around planets, etc. That movement is tracked by telescopes on the ground run by many countries and even amateur astronomers (mostly satellites). NASA runs the NASA Deep Space Network
    The NASA Deep Space Network (DSN) is a worldwide network of U.S. spacecraft communication facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA's interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the Solar System and the universe, and supports selected Earth-orbiting missions. DSN is part of the NASA Jet Propulsion Laboratory (JPL). Similar networks are run by Russia, China, India, Japan and the European Space Agency.
    There is video footage confirming that spacecraft use rockets to move through vacuum, e.g. spacecraft arriving and leaving the International Space Station. Astronauts use rockets (astronaut propulsion unit) to move in the vacuum of space.

    We have spacecraft and robots throughout the solar system being tracked and sending back information.
    rockethunter, how did the Curiosity rover get to Mars through the vacuum of space?
    Last edited by Reality Check; 2019-Mar-13 at 03:33 AM.

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    Quote Originally Posted by rockethunter View Post
    Do you have any proof of this? When I dead lift 100kg (I am 75kg) and I drop it from a height, do I get lifted off the ground. Because that is basically what you are saying.
    If there were no gravity you would, because you would have to push it downward. In your case, you are letting gravity do the work for you, so actually the earth is moving up toward the barbell.
    As above, so below

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    Quote Originally Posted by rockethunter View Post
    Do you have any proof of this? When I dead lift 100kg (I am 75kg) and I drop it from a height, do I get lifted off the ground. Because that is basically what you are saying.
    Erm, no. Once you let go of the weight you are (obviously) no longer exerting force on it. The equal and opposite forces are the weight pulling on the earth, and the earth pulling on the weight. We can't directly measure the acceleration this causes on the earth, because the earth is so much more massive than the weight. But we can observe it in other astronomical bodies: for example, we can measure the sun's wobble caused by the pull of the planets. The gravitational force between two masses was also first experimentally measured in the late 1700's.

    Quote Originally Posted by rockethunter View Post
    It does decay. In every rocket launch video you can see this decay as the rocket starts to move sideways.
    All launches to low earth orbit end up with roughly zero vertical velocity and very high horizontal velocity, so they definitely do start to move "sideways". That doesn't mean the thrust is decaying (all else being equal, the acceleration is increasing as the rocket burns away mass): it means that the rocket is turning away from vertical. From an observer's perspective at the launch site, this effect is amplified by the horizon caused by the curvature of the earth - the disappears over the horizon like a ship sailing into the distance.

    If rocket thrust decayed at lower ambient pressures, do you think air-to-air missiles have shorter or longer ranges when launched at high altitudes?

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    Quote Originally Posted by rockethunter View Post
    I believe I have experimented to my satisfaction. There is no other proof, other than NASA fake video footage, of rockets working in a vacuum.
    ...and of course, NASA is the only organisation on Earth that has put anything into space...

    Can.you clarify - do you think that nothing can get into space at all, or just that nothing can leave a low Earth orbit? I'm just curious as to how far this misapprehension of yours extends.

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    Quote Originally Posted by rockethunter View Post
    Experiments in here show no opposite reaction due to gas movement due to pressure differential. At the end of the video, the NASA thrust equation if invalidated.

    https://www.youtube.com/watch?v=AubIFUsq7Ss




    Here is another independent video.

    https://www.youtube.com/watch?v=D-v_K1k8Se0
    Obviously you didn't read my post. What experiments have you done and what was measured in these experiments. Consider this a second request to answer the question.

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