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 International Skeptics Forum Merged: Rockets cannot propel in the vacuum of space.

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 17th April 2019, 11:46 AM #121 Armitage72 Master Poster   Join Date: Mar 2012 Posts: 2,836 Originally Posted by Belz... What part of "it can't go through the engine bell walls" is causing you issues? I know this one. I remember it from an old Stundie post that compared rockets to a can of silly string. The rocket doesn't actually push the exhaust out of the nozzle, so the walls don't matter. The vacuum instantly pulls the exhaust out of the rocket and into itself, so there's no thrust. ETA: Found it. Originally Posted by smartcooky I submit this pearl of wisdom, from cluesforum.info Thread: Why Rocketry Doesn't Work in the Vacuum Poster: Vext Lynchpin Date: June 18th, 2013, 8:00 pm ""I think the main point that the posters on this thread (who are more scientifically minded than I) have been making is that the vacuum itself exerts a force of its own that renders nil the force of the mass of gas escaping from a rocket's nozzle. To use a simple analogy, think of a rocket and its escaping gas as an aerosol can full of silly string. When you press the button on the aerosol can, silly string is ejected at great speed. If there's enough speed, it may exert force on the aerosol can, so that the silly string is moving in one direction, and the can in the other. Newton. But in a vacuum, the speed of the equalizing force of the vacuum is akin to someone pulling the silly string out of the aerosol can faster than it can be ejected, thus nullifying the force caused by the silly string's ejection. Of course, the analogy isn't perfect, since pulling the silly string out would actually cause the aerosol can to move in the same direction as the pull. This wouldn't be a factor with gases being pulled into the vacuum." Last edited by Armitage72; 17th April 2019 at 11:50 AM.
 17th April 2019, 11:48 AM #122 bknight Graduate Poster     Join Date: Apr 2017 Location: Houston, Texas Posts: 1,544 Originally Posted by Belz... Well, he quotes movies as if they are wisdom and seems to have a movie understanding of science. Par for the course. Wow, solipsism, so fast? The problem is, you don't want it proved. You've set yourself up to be impossible to convince anyway. Part of having an open mind is realising that you can be wrong, and you've discarded that. Density. Don't get things mixed up. Focus. That would stop the Gish gallop, which seems to be his trade mark.
 17th April 2019, 11:50 AM #123 JoeMorgue Self Employed Remittance Man     Join Date: Nov 2009 Location: Florida Posts: 17,943 It's not like you have to go to space to find a vacuum. This isn't some theoretical question we have to build a super collider the size of the moon to solve. This could be answered in any vacuum chamber here on Earth with Diet Coke and Mentos. __________________ - "Ernest Hemingway once wrote that the world is a fine place and worth fighting for. I agree with the second part." - Detective Sommerset - "Stupidity does not cancel out stupidity to yield genius. It breeds like a bucket-full of coked out hamsters." - The Oatmeal - "To the best of my knowledge the only thing philosophy has ever proven is that Descartes could think." - SMBC Last edited by JoeMorgue; 17th April 2019 at 12:40 PM.
 17th April 2019, 12:05 PM #124 GlennB Loggerheaded, earth-vexing fustilarian     Join Date: Sep 2006 Location: Arcadia, Greece Posts: 24,717 Originally Posted by JoeMorgue It's not like you have to go to space to find a vacuum. This isn't some theoretical question we have to build a super collider the size of the moon to solve. This answered in any vacuum chamber here on Earth with Diet Coke and Mentos. Exactly. But the video would have to be verifiably uneditable, which is tricky to prove. And if Gingervytes were actually there to witness the experiment he'd have to be in the chamber to check that it's really a vacuum. Looks like an irreducible delusion to me. __________________ "Even a broken clock is right twice a day. 9/11 truth is a clock with no hands." - Beachnut
 17th April 2019, 12:07 PM #125 Armitage72 Master Poster   Join Date: Mar 2012 Posts: 2,836 Originally Posted by JoeMorgue It's not like you have to go to space to find a vacuum. This isn't some theoretical question we have to build a super collider the size of the moon to solve. This answered in any vacuum chamber here on Earth with Diet Coke and Mentos. Any thrust would be the result of the exhaust pushing against the wall of the chamber, obviously.
 17th April 2019, 12:09 PM #126 smartcooky Penultimate Amazing     Join Date: Oct 2012 Location: Nelson, New Zealand Posts: 11,632 The "NASA" rocket equation? I thought it was the Tsiolkovsky rocket equation. Oh, I get it.... Tsiolkovsky was "in on it", a NASA shill, 62 years before NASA was even established. __________________ #THEYAREUS The Mueller Report must be released to Congress in full - If Trump has nothing to hide, then he should also have nothing to fear!
 17th April 2019, 12:12 PM #127 dasmiller Just the right amount of cowbell     Join Date: Oct 2008 Location: Well past Hither, looking for Yon Posts: 6,194 Originally Posted by smartcooky The "NASA" rocket equation? I thought it was the Tsiolkovsky rocket equation. Oh, I get it.... Tsiolkovsky was "in on it", a NASA shill, 62 years before NASA was even established. I think "NASA" means he got that equation from NASA. Tsiolkovsky's equation is different and almost (but not entirely) unrelated. Tsiolkovsky's rocket equation is about total delta-V; thrust is merely implied because without thrust, the specific impulse would always be 0. __________________ "In times of war, we need warriors. But this isn't a war." - Phil Plaitt
 17th April 2019, 12:14 PM #128 smartcooky Penultimate Amazing     Join Date: Oct 2012 Location: Nelson, New Zealand Posts: 11,632 Originally Posted by dasmiller I think "NASA" means he got that equation from NASA. Tsiolkovsky's equation is different and almost (but not entirely) unrelated. Tsiolkovsky's rocket equation is about total delta-V; thrust is merely implied because without thrust, the specific impulse would always be 0. Oh, OK I didn't bother reading his attachment. Its sideways, and I have a sore neck this morning. __________________ #THEYAREUS The Mueller Report must be released to Congress in full - If Trump has nothing to hide, then he should also have nothing to fear!
 17th April 2019, 12:18 PM #129 JayUtah Penultimate Amazing     Join Date: Sep 2011 Posts: 17,185 Originally Posted by smartcooky I didn't bother reading his attachment. Its sideways, and I have a sore neck this morning. tl;dr "I can substitute this for that." Refuation: No, you can't. They are dissimilar concepts.
 17th April 2019, 12:35 PM #130 dudalb Penultimate Amazing     Join Date: Aug 2007 Location: Sacramento Posts: 43,936 Maybe this should be moved to the Science section here, since that seem to be the place for crackpot science theories. I am not denying there is a conspiracy angle, but overall I think this should be dealt with as crackpot science. __________________ Pacifism is a shifty doctrine under which a man accepts the benefits of the social group without being willing to pay - and claims a halo for his dishonesty. Robert Heinlein.
 17th April 2019, 12:39 PM #131 bknight Graduate Poster     Join Date: Apr 2017 Location: Houston, Texas Posts: 1,544 Originally Posted by dasmiller I think "NASA" means he got that equation from NASA. Tsiolkovsky's equation is different and almost (but not entirely) unrelated. Tsiolkovsky's rocket equation is about total delta-V; thrust is merely implied because without thrust, the specific impulse would always be 0. Yes but it requires fuel mass turned into gas mass to achieve that delta v.
 17th April 2019, 12:45 PM #132 dasmiller Just the right amount of cowbell     Join Date: Oct 2008 Location: Well past Hither, looking for Yon Posts: 6,194 Originally Posted by bknight Yes but it requires fuel mass turned into gas mass to achieve that delta v. Tsiolkovsky's rocket equation doesn't assume gas at all, merely that mass is ejected to create thrust (e.g. there's reaction mass). The Rocket Equation works just fine if, instead of thrusters, you have little slingshots firing mass slugs, or you're using a water rocket __________________ "In times of war, we need warriors. But this isn't a war." - Phil Plaitt
 17th April 2019, 12:52 PM #133 JayUtah Penultimate Amazing     Join Date: Sep 2011 Posts: 17,185 We did an design exercise once to see whether you could pee with enough thrust to lift yourself off an asteroid.
 17th April 2019, 12:53 PM #134 cow_cat Mr. Parodied     Join Date: Feb 2006 Location: Between the Sun and the Stars Posts: 1,598 The thing is, NASA (and other private companies) live-stream the launches, then afterwards the whole thing is available to view on youtube. For instance, Northrop Grumman are sending up an Antares resupply mission to the ISS, launching in about 40 minutes from now. You can watch the live stream now, here. https://www.rocketlaunch.live/?filter=northrop-grumman They are prepping the rocket now, and you can actually watch it all the way up from 0m above ground to space. Go and look! __________________ Now that is Scientific Fact. There's no real evidence for it, but it is Scientific Fact. -'Dr' Neil Fox, speaking on brasseye Used to have another username, but I hated it.
 17th April 2019, 12:55 PM #135 bknight Graduate Poster     Join Date: Apr 2017 Location: Houston, Texas Posts: 1,544 Originally Posted by dasmiller Tsiolkovsky's rocket equation doesn't assume gas at all, merely that mass is ejected to create thrust (e.g. there's reaction mass). The Rocket Equation works just fine if, instead of thrusters, you have little slingshots firing mass slugs, or you're using a water rocket Fair enough I was attempting to put it into terms our OP might grasp. https://en.wikipedia.org/wiki/Tsiolk...ocket_equation
 17th April 2019, 01:04 PM #136 lionking In the Peanut Gallery     Join Date: Jan 2007 Location: Melbourne Posts: 43,688 Well one good thing has come from this thread. I’ve obviously accepted that rockets work in space, but I’ve never taken the time to understand how. Now I have a much better understanding, so thanks to Jay and others. __________________ A fanatic is one who can't change his mind and won't change the subject. Sir Winston Churchill
 17th April 2019, 01:04 PM #137 phunk Illuminator     Join Date: Aug 2007 Posts: 3,977 Originally Posted by JayUtah We did an design exercise once to see whether you could pee with enough thrust to lift yourself off an asteroid. Don't leave us hanging, what was the result?
 17th April 2019, 01:06 PM #138 dasmiller Just the right amount of cowbell     Join Date: Oct 2008 Location: Well past Hither, looking for Yon Posts: 6,194 Originally Posted by bknight Fair enough I was attempting to put it into terms our OP might grasp. Ah, a worthy challenge. And I suppose I was being a bit pedantic; offhand I don't know of any real-world space propulsion systems* that aren't arguably using gas** for reaction mass. *Not including propulsion systems that don't have a traditional reaction mass, e.g. lightsails or clever ways to push off Earth's magnetic field. **in this context, "gas" includes traditional gas (e.g. N2), plasma, and streams of ionized noble gasses. __________________ "In times of war, we need warriors. But this isn't a war." - Phil Plaitt
 17th April 2019, 01:06 PM #139 sts60 Illuminator     Join Date: Jul 2007 Posts: 3,191 Originally Posted by cow_cat The thing is, NASA (and other private companies) live-stream the launches, then afterwards the whole thing is available to view on youtube. For instance, Northrop Grumman are sending up an Antares resupply mission to the ISS, launching in about 40 minutes from now. You can watch the live stream now, here. https://www.rocketlaunch.live/?filter=northrop-grumman They are prepping the rocket now, and you can actually watch it all the way up from 0m above ground to space. Go and look! Watched an Antares launch in the wee small hours once. The Wallops visitor center parking lot was full at 2 AM, and people were off parking on the roadside.
 17th April 2019, 01:15 PM #140 bknight Graduate Poster     Join Date: Apr 2017 Location: Houston, Texas Posts: 1,544 Originally Posted by dasmiller Ah, a worthy challenge. And I suppose I was being a bit pedantic; offhand I don't know of any real-world space propulsion systems* that aren't arguably using gas** for reaction mass. *Not including propulsion systems that don't have a traditional reaction mass, e.g. lightsails or clever ways to push off Earth's magnetic field. **in this context, "gas" includes traditional gas (e.g. N2), plasma, and streams of ionized noble gasses. I'm not an aerospace engineer, but rather an inner space engineer, so some of these calculations are new to me, but I understand the math, although I'm quite sure I couldn't solve them. I didn't take offense at your correction, BTW.
 17th April 2019, 01:19 PM #141 bknight Graduate Poster     Join Date: Apr 2017 Location: Houston, Texas Posts: 1,544 Originally Posted by sts60 Watched an Antares launch in the wee small hours once. The Wallops visitor center parking lot was full at 2 AM, and people were off parking on the roadside. Looking at te launch pad with the bay/ocean on the right, where is the parking lot?
 17th April 2019, 01:23 PM #142 MRC_Hans Penultimate Amazing     Join Date: Aug 2002 Posts: 22,070 Originally Posted by Gingervytes And gas moving out of the chamber is due to pressure gradient force Yes. Pressure. The pressure accelerates the gas out. Where is the other side of that pressure? Hans __________________ Experience is an excellent teacher, but she sends large bills.
 17th April 2019, 01:32 PM #143 Gingervytes Critical Thinker   Join Date: Mar 2019 Posts: 283 Originally Posted by MRC_Hans Yes. Pressure. The pressure accelerates the gas out. Where is the other side of that pressure? Hans Is there pressure still pushing. Let us put an object on a scale and pick it up with a vacuum, why is there no opposite force on the scale?
 17th April 2019, 01:33 PM #144 JoeMorgue Self Employed Remittance Man     Join Date: Nov 2009 Location: Florida Posts: 17,943 "If NASA was willing to fake great accomplishments they'd have a second one by now." - xkcd. __________________ - "Ernest Hemingway once wrote that the world is a fine place and worth fighting for. I agree with the second part." - Detective Sommerset - "Stupidity does not cancel out stupidity to yield genius. It breeds like a bucket-full of coked out hamsters." - The Oatmeal - "To the best of my knowledge the only thing philosophy has ever proven is that Descartes could think." - SMBC
 17th April 2019, 01:34 PM #145 JoeMorgue Self Employed Remittance Man     Join Date: Nov 2009 Location: Florida Posts: 17,943 Originally Posted by Gingervytes Let us put an object on a scale and pick it up with a vacuum, why is there no opposite force on the scale? Because gravity and thrust aren't the same thing. __________________ - "Ernest Hemingway once wrote that the world is a fine place and worth fighting for. I agree with the second part." - Detective Sommerset - "Stupidity does not cancel out stupidity to yield genius. It breeds like a bucket-full of coked out hamsters." - The Oatmeal - "To the best of my knowledge the only thing philosophy has ever proven is that Descartes could think." - SMBC
 17th April 2019, 01:37 PM #146 Dr.Sid Graduate Poster   Join Date: Sep 2009 Location: Olomouc, Czech Republic Posts: 1,895 Btw. the atmospheric pressure actually plays role. It lowers efficiency of rocket engine, as the speed through the nozzle depends on difference between pressures inside the engine and outside. If there was enough outside pressure, the gasses would just stay inside, and no work would be done.
 17th April 2019, 01:38 PM #147 JoeMorgue Self Employed Remittance Man     Join Date: Nov 2009 Location: Florida Posts: 17,943 Originally Posted by Dr.Sid Btw. the atmospheric pressure actually plays role. It lowers efficiency of rocket engine, as the speed through the nozzle depends on difference between pressures inside the engine and outside. If there was enough outside pressure, the gasses would just stay inside, and no work would be done. Shill. Who's lining your pockets? No seriously who. I want in. __________________ - "Ernest Hemingway once wrote that the world is a fine place and worth fighting for. I agree with the second part." - Detective Sommerset - "Stupidity does not cancel out stupidity to yield genius. It breeds like a bucket-full of coked out hamsters." - The Oatmeal - "To the best of my knowledge the only thing philosophy has ever proven is that Descartes could think." - SMBC
 17th April 2019, 01:40 PM #148 MRC_Hans Penultimate Amazing     Join Date: Aug 2002 Posts: 22,070 Originally Posted by Gingervytes Is there pressure still pushing. Let us put an object on a scale and pick it up with a vacuum, why is there no opposite force on the scale? Why should there be? Anyway, irrelevant. Stay on topic: The gas is accelerated out of the rocket by pressure. Pressure is a force. Where is the opposing force to the pressure? ... I'll save some iterations (and predictable diversions) by answering the question. The force acts in two directions: 1) Against the gas, which is accelerated and leaves the rocket. What happens to the gas afterwards is essentially irrelevant. 2) Opposite, against the bottom of the combustion chamber. The force of this pressure is what propels the rocket. (actually it works in all directions, against the side walls of the chamber, but these forces cancel out.) Hans __________________ Experience is an excellent teacher, but she sends large bills.
 17th April 2019, 01:41 PM #149 JoeMorgue Self Employed Remittance Man     Join Date: Nov 2009 Location: Florida Posts: 17,943 Don't do it. Don't get drug down into nitpicking the details when the core argument is fundamentally flawed. He's trying to Jabba us. __________________ - "Ernest Hemingway once wrote that the world is a fine place and worth fighting for. I agree with the second part." - Detective Sommerset - "Stupidity does not cancel out stupidity to yield genius. It breeds like a bucket-full of coked out hamsters." - The Oatmeal - "To the best of my knowledge the only thing philosophy has ever proven is that Descartes could think." - SMBC
17th April 2019, 01:42 PM   #150
smartcooky
Penultimate Amazing

Join Date: Oct 2012
Location: Nelson, New Zealand
Posts: 11,632
Don't believe rockets work in a vacuum?

Watch the demo

 YouTube Video This video is not hosted by the ISF. The ISF can not be held responsible for the suitability or legality of this material. By clicking the link below you agree to view content from an external website. I AGREE
__________________
#THEYAREUS
The Mueller Report must be released to Congress in full - If Trump has nothing to hide, then he should also have nothing to fear!

 17th April 2019, 01:46 PM #151 cow_cat Mr. Parodied     Join Date: Feb 2006 Location: Between the Sun and the Stars Posts: 1,598 Originally Posted by sts60 Watched an Antares launch in the wee small hours once. The Wallops visitor center parking lot was full at 2 AM, and people were off parking on the roadside. Very nice. I only ever saw one launch, of Shuttle STS111 from a friend's place across the river. Wallops looks like a very nice place to observe from. But of course none of this ever happened because rockets are a lie. Or some such thing... __________________ Now that is Scientific Fact. There's no real evidence for it, but it is Scientific Fact. -'Dr' Neil Fox, speaking on brasseye Used to have another username, but I hated it.
 17th April 2019, 02:16 PM #152 Dancing David Penultimate Amazing     Join Date: Mar 2003 Location: central Illinois Posts: 39,640 Originally Posted by Gingervytes Too ignorant to even try understanding the argument maybe the problem is in your argument that perhaps you can not express clearly, dasmiller has great comprehension, perhaps you should try to actually explain your self in more than sound bytes. __________________ I suspect you are a sandwich, metaphorically speaking. -Donn And a shot rang out. Now Space is doing time... -Ben Burch You built the toilet - don't complain when people crap in it. _Kid Eager Never underestimate the power of the Random Number God. More of evolutionary history is His doing than people think. - Dinwar
 17th April 2019, 02:17 PM #153 Steve Philosopher     Join Date: May 2005 Posts: 5,056 Originally Posted by phunk Don't leave us hanging, what was the result? Yeah, some real science is neede here. __________________ Caption from and old New Yorker cartoon - Why am I shouting? Because I'm wrong!"
 17th April 2019, 02:24 PM #154 sts60 Illuminator     Join Date: Jul 2007 Posts: 3,191 Originally Posted by bknight Looking at te launch pad with the bay/ocean on the right, where is the parking lot? I’m not quite sure I understand your perspective, but the visitor center is north of the pad.
 17th April 2019, 02:25 PM #155 sts60 Illuminator     Join Date: Jul 2007 Posts: 3,191 Originally Posted by Gingervytes Is there pressure still pushing. Let us put an object on a scale and pick it up with a vacuum, why is there no opposite force on the scale? Nope. Answer the questions and rebuttals already put to you.
 17th April 2019, 02:31 PM #156 Belz... Fiend God     Join Date: Oct 2005 Location: In the details Posts: 82,192 Originally Posted by Gingervytes Is there pressure still pushing. Let us put an object on a scale and pick it up with a vacuum, why is there no opposite force on the scale? Gravity isn't a sort of thrust. The thing is, you can do these experiments of thrust yourself. There are places where they can damn near make vaccuums for you, and you can find some pressurised container, make a whole in it, and see it move. So why are you wasting time on web forums rather than testing your idea? __________________ Master of the Shining Darkness "My views are nonsense. So what?" - BobTheCoward
17th April 2019, 02:34 PM   #157
Dr.Sid

Join Date: Sep 2009
Location: Olomouc, Czech Republic
Posts: 1,895
Originally Posted by smartcooky
Don't believe rockets work in a vacuum?

Watch the demo

 YouTube Video This video is not hosted by the ISF. The ISF can not be held responsible for the suitability or legality of this material. By clicking the link below you agree to view content from an external website. I AGREE
Well small engines MAYBE, but what about the big ones, ha ? You can't even fit them in vacuum this small.

 17th April 2019, 02:37 PM #158 JayUtah Penultimate Amazing     Join Date: Sep 2011 Posts: 17,185 Originally Posted by Gingervytes Let us put an object on a scale and pick it up with a vacuum, why is there no opposite force on the scale? Because gravity and momentum are two different kinds of things. None of your would-be analogies has the slightest to do with how rockets actually work. It's just a bunch of cargo-cult nonsense.
 17th April 2019, 02:55 PM #159 JayUtah Penultimate Amazing     Join Date: Sep 2011 Posts: 17,185 Originally Posted by Belz... Gravity isn't a sort of thrust. Nor is mechanical traction, although if you pull hard on something it will pull back. If instead of placing an object on a scale and pulling upward, you place a spring scale between an object and the hoist, the scale will register an increase in load as you begin to pull. This is inertial reaction, which combines with gravity to produce the scale reading. This is why crane operators take care not to lift speedily. The cable and tackle may well support the load's static weight, but not the additional dynamic force you might apply by starting and stopping the load abruptly. Lifting something off a scale by drawing it upward into a vacuum immediately severs the coupling between the object and the scale. That much is obvious. However, put a giant scale underneath a rocket and measure the impingement force of its exhaust, and you will continue to get a reading as the rocket lifts off and stops weighing down the scale. Quote: So why are you wasting time on web forums rather than testing your idea? Or collecting his Nobel prize in physics for having toppled Newton's laws of motion.
 17th April 2019, 03:16 PM #160 Trebuchet Penultimate Amazing     Join Date: Nov 2003 Location: The Great Northwet Posts: 21,430 Here, just for grins, is a seriously similar thread at Cosmoquest, where we miss Jay Utah. __________________ Cum catapultae proscribeantur tum soli proscripti catapultas habeant.

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