Does Rocketry Work beyond Earth's atmosphere?

If NASA faked the moon landings, does the agency have any credibility at all? Was the Space Shuttle program also a hoax? Is the International Space Station another one? Do not dismiss these hypotheses offhand. Check out our wider NASA research and make up your own mind about it all.
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lux
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Re: Does Rocketry Work in the Vacuum?

Unread post by lux » Sat Jan 24, 2015 12:10 pm

P from the UK wrote:Hello again Simon.

...

But if you want an even simpler (& more practical) demonstration of how NASA's model of rocket propulsion is flawed, then take an ordinary firework rocket & attach a shield to it, just below the nozzle, thus blocking the exhaust from interacting with the atmosphere.

According to NASA it should still take off, as the work is being done within the rocket itself, but of course it will not; it will merely sit & sputter & go absolutely nowhere..
Trust me, the last entity on Earth I would ever defend is NASA. However, I have to take issue with this statement.

The author does not cite a reference where NASA said such a contraption would "still take off" and of course they would never say such an obviously idiotic thing as they still have to keep up some semblance of believability for all those physics students who would see through such idiocy immediately. Of course such a rocket would just "sit & sputter and go absolutely nowhere" and NASA would never claim otherwise.

The key word in the description of this experiment is "attach."
... take an ordinary firework rocket & attach a shield to it, just below the nozzle, thus blocking the exhaust from interacting with the atmosphere.
Obviously if such a shield were attached to the rocket then the exhaust would apply as much force to the shield as to the rest of the rocket and, since this shield is attached to the rocket, no motion would result. A shield that was not attached to the rocket, however, would not prevent it from taking off.

I certainly don't mind criticisms of NASA but when criticisms are made in such a fallacious and unsupported manner it tends to feed the flames of criticism of this forum and makes us all appear like idiots for not calling foul on statements like this. Perhaps that is the purpose of this “contributor” who refuses to even register on the forum?

The above is far from the only unsupported claim made on his thread and I can't help but wonder where the usual standards of research such as citing sources, etc have gone?

There are ways of proving, or at least demonstrating, the concepts of "rocket propulsion doesn't work in a vacuum" or of "rockets push against the air" as has been claimed. Small vacuum chambers, such as those used in class room demonstrations, do exist and are not expensive. Experiments involving propulsion from rearward expelling of masses can be done with models or even skateboards and weights, and so on.

How about the proponents of these concepts showing us some real world demos? Throwing theories and equations around is easy and can be done comfortably from one's easy chair. How about providing some -- dare I say it? -- real world PROOF?

And, by proof, I don't mean just saying "if you do this ..." or " if you do that ..." or drawing pictures and diagrams. I mean actually getting out of your chair and DOING it and SHOWING us. Or, at least pointing toward someone who has done it ... for real.

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Re: Does Rocketry Work in the Vacuum?

Unread post by SteinUntStein » Sat Jan 24, 2015 2:27 pm

hoi.polloi wrote:The problem with the car analogy is that you have ground and a strong, direct form of friction to work with. The rockets should be beating 9.8 m/s^2 from the start because they have nothing to "climb" or "grab on to". This is what the ships are apparently doing according to the falsified videos of the launches, except that it's so torturously slow, they should be encountering far more internal friction problems than they talk about or care to explain with anything other than the faked videos, magic diagrams of vague ship guts and fairy-tales of secret formulas.

From my understanding, initial calculations of rockets (if you believe those, even) were saying they were going to have to be like skyscrapers to achieve the power and the heights they claim to have done with the toys they show on TV.

Correct me if I'm wrong.
I don't know what's right or wrong here it's what I am trying to figure out. As for my analogy, this is assuming their thrusters work. If they work, the analogy would hold, seems to me.

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Re: Does Rocketry Work in the Vacuum?

Unread post by SteinUntStein » Sat Jan 24, 2015 2:31 pm

Selene wrote:Space is not only a vacuum (the pressure discussion for the past 31 interesting and great pages), it is also absolutely stone cold. There's nothing.
Actually not a vacuum, theoretically no such thing as a vacuum. But again, to know the constituency of outer space, you would have to have BEEN to space, seems to me.

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Re: Does Rocketry Work in the Vacuum?

Unread post by SteinUntStein » Sat Jan 24, 2015 2:42 pm

lux wrote:...
There are ways of proving, or at least demonstrating, the concepts of "rocket propulsion doesn't work in a vacuum" or of "rockets push against the air" as has been claimed. Small vacuum chambers, such as those used in class room demonstrations, do exist and are not expensive. Experiments involving propulsion from rearward expelling of masses can be done with models or even skateboards and weights, and so on.
...
And, by proof, I don't mean just saying "if you do this ..." or " if you do that ..." or drawing pictures and diagrams. I mean actually getting out of your chair and DOING it and SHOWING us. Or, at least pointing toward someone who has done it ... for real.
Actually this has been part of the problem. The following are terrestrial facts:
1. There is no such thing as a vacuum, unless you mean what you clean the floor with. I dare say it is impossible and a lie. None have ever been devised. You can suck out most of the matter ppm but you can't get it all out. Those cheap toys in school are just that, cheap toys. The concept here is part of the problem.
2. All the experiments have been done in partial vacuum, meaning, simply very low ppm.

lux
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Re: Does Rocketry Work in the Vacuum?

Unread post by lux » Sat Jan 24, 2015 7:32 pm

^ Space is not a true vacuum either, were told.

In any case, approaching a vacuum with experiments could at least lend some supporting evidence.

I asked a question earlier which has so far been ignored by the armchair physicists on this thread: Do rockets fly slower at higher altitudes than at lower? The answer may not solve the puzzle but it at least asks for real world data. My guess is no one on this thread knows or cares about the answer.

And, there is still the matter of propulsion via expelling mass which does not necessarily depend on a vacuum to prove or to at least demonstrate.

Personally, I don't really care if rockets work in space or not. A rocket wouldn't be practical for the kinds of distances involved in real space travel anyway (my opinion). By the time you got anywhere you'd be long gone from radiation, heat, cold, meteorites, starvation, suffucation, etc., etc. or just frigging lost. Aluminum cans don't hold up well against rocks moving at tens of thousands of mph nor would they provide much protection from other space hazards (except for NASA's magic space ships, of course). :lol:

I just care about doing valid research.

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Re: Does Rocketry Work in the Vacuum?

Unread post by Selene » Sat Jan 24, 2015 7:54 pm

Pilgrim wrote:Hi Selene, I fail to see what difference the temperature of "space" makes to the fact that Rockets cannot produce a thrust in a vacuum. A vacuum by its own definition has no matter to hold any temperature so is neither hot or cold and the fact the Rocket gases are hot and can only lose heat by radiation in a vacuum which takes time seems irrelevant to the immediate fact of whether they are hot gases or cold gases in terms of thrust produced by expelled mass. It should make no difference according to their logic. Of course I agree with the OP - only a reaction with another mass can produce an opposite reaction and Rocket fumes have nothing to react against in vacuum due to no pressure against anything as the vacuum offers zero resistance and will suck up all you have to offer with zero resistance so no "thrust" is possible.
Hi Pilgrim,

it's not so much a "difference", it's more that there are more parameters affecting the behaviour of rockets in a near vacuum.

If not only the Pressure is ~0, but also the Temperature ~0 (or 2.7 K as Wiki says), then material behaviour is completely different to whatever circumstance we know of.

I agree with lux that we should have a thorough research into the topic, but it will be hard to find "lab tests" where AND Pressure AND Temperature are almost 0. And not to forget the radiation which is impossible to test as we do not even know which kinds of radiation are there. And the lack of gravity, also impossible to test. We might ask NASA to show us the test in their vomit comet, with vacuum conditions, as 24 cosmoclowns allegedly traveled to the Moon, that shouldn't be such a problem, right?

The chemical changes to the materials (either gaseous as the rocket fuel or solid as the metal can) couldn't be circumvented.

The near vacuum, so incredibly low Pressure, makes there is no friction between the rocket and space. How would you describe the temperature profile from inside to outside?

Inside - a nice comfortable 20 degrees C?
Outside - heated due to radiation? - how would this heat be transferred?
Space - near zero temperatures

The outside of the spacecraft would have such enormous temperature fluctuations even when and if it can be heated by solar radiation alone, that only that would make the rocket/craft behave very strangely.

In short, to answer your question; the pressure is indeed a crucial point, but even so crucial is the temperature which until recently was not included in the discussion.

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Re: Does Rocketry Work in the Vacuum?

Unread post by simonshack » Sat Jan 24, 2015 9:01 pm

lux wrote:
My guess is no one on this thread knows or cares about the answer.

(...)

Personally, I don't really care if rockets work in space or not.

(...)

I just care about doing valid research.
Care to clarify? D'you care - or caren't you ? That is The Question.

As for your 'armchair physicists' comment, I'm sure you meant no offense - or else you would have typed "wheelchair physicists". :P

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Re: Does Rocketry Work in the Vacuum?

Unread post by lux » Sat Jan 24, 2015 9:24 pm

I don't understand. Do you see a contradiction in those 3 sentences of mine?

I just couldn't resist a little ranting when I saw that comment about a shield attached to a rocket but I'm happy to sit this thread out if I'm being a party pooper.

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Re: Does Rocketry Work in the Vacuum?

Unread post by simonshack » Sat Jan 24, 2015 10:33 pm

lux wrote:I don't understand. Do you see a contradiction in those 3 sentences of mine?

I just couldn't resist a little ranting when I saw that comment about a shield attached to a rocket but I'm happy to sit this thread out if I'm being a party pooper.
Yes, Lux - your 3 sentences strike me as a tad contradictory, but maybe it's just me.

Besides, we are not exactly having a jolly party here - so there is no party to poop. A jolly "party" is a more apt description of what NASA has had ever since its inception - defrauding ALL of us honest citizens, armchair scientists included. Most of us here are just trying our damndest best to restore some sanity in this long-degenerated, foolish and mind-numbing "party" ruthlessly imposed on us all by NASA & Co for well over half a century now. These shamelessly arrogant party-throwers are universally hailed as the 'most eminent scientific brains' of this planet. Therefore, I don't think that ANY sarcasm or snide remarks against our members are appropriate in the context of our valiant, collective efforts on this forum.

lux
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Re: Does Rocketry Work in the Vacuum?

Unread post by lux » Sat Jan 24, 2015 11:10 pm

To clarify, the armchaim remark was directed at Boetheus who has insulted all of us on another forum and also to the guy who made the rocket shield remark who isn't a member here. I will apologize to Boethius just as soon as he apologizes to the forum for the prior insults he wrote about us on LRF.

If you, Simon, or anyone else felt insulted by my armchair remark, I apologize. It wasn't meant for you.

I will now let you all carry on with this thread without my input. :)

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Re: Does Rocketry Work in the Vacuum?

Unread post by Selene » Sat Jan 24, 2015 11:23 pm

lux wrote:I will now let you all carry on with this thread without my input. :)
That would be a pity, lux. :)

You said you have doubts with space travel because of the radiation, length, etc. And as far as I understood, you don't agree with Boethius vision on thrust & (near) vacuum?

What about combining your expressed doubts and the points of Boethius and let's throw temperature in the equation as well?

Would there be any pre-NASA source that can help us tackling this problem? In the 50's they must have published about this most interesting question, right? Could we leave this Earth with a craft/rocket at all?

Later I will look for pre-NASA publications myself, will be somewhere coming week.

lux
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Re: Does Rocketry Work in the Vacuum?

Unread post by lux » Sun Jan 25, 2015 12:03 am

Selene wrote:
lux wrote:I will now let you all carry on with this thread without my input. :)
That would be a pity, lux. :)

You said you have doubts with space travel because of the radiation, length, etc.
Doubts about serious space travel (to another planet, etc) using one of NASA's aluminum rockets, yes, many doubts. Rockets may have some minor uses in space but not as a main propulsion method. Apart from what I've already opined about rockets, NASA can't even decide if one can see stars in space so how would they even navigate a rocket across millions of miles ... if they managed to get one out there? You can't triangulate from Earth when Earth is just a dot in the far distance.
And as far as I understood, you don't agree with Boethius vision on thrust & (near) vacuum?
Correct but this has all been discussed before and I don't wish to re-hash it. I'm fine with letting others discuss it. Really -- it's not a big deal to me. I'm not leaving the forum or anything. I just don't wish to get into a debate on this topic.

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Re: Does Rocketry Work in the Vacuum?

Unread post by Pilgrim » Sun Jan 25, 2015 12:34 am

"Every action has an equal and opposite reaction" I think that has only been shown to be more or less true when actual masses react against each other. If i am on a skateboard and throw a medicine ball away from myself then i am both pushing myself backwards against the medicine ball and propelling the ball forward against my own mass. As I have a greater mass than the ball then the ball will go more forward than i will backward.
This analogy has been shown to be falsely used to justify Rocket thrust in a vacuum as the Rocket plume exhaust equates to my muscles actually pushing against the medicine ball and not the actual medicine ball itself being ejected by me as mass creating opposite force or thrust as in the case of Rocket engines.
I can punch the air with a force but i will not be propelled backwards with the same force as the air offers little resistance to my hand, if i did the same in water i would feel more resistance and if I punch a solid object like a wall then i would be propelled backwards even more.
That it's the mass of the medium (or opposing pressure created by mass) in which a force is applied against to get any opposite reaction such as air, water or solid masses is self evident from experience and reality.
A Fireman's hose will produce a thrust against the air pressure but nothing like as much force as if the same power was used for liquid or gases used in closed systems such as pneumatic applications and "push" against solid objects rather than air pressure.
If i had a pump that sucks up water from the end of the Fireman's nozzle at the same rate it was being expelled then as there is zero resistance to the ejected mass, then there can be no opposite reaction and space vacuum offers the ultimate pump that "sucks" up all you have to offer as the ejecting mass can just carry on with no resistance whatsoever to produce a force against and there is no mass to react against.
Can anyone offer another example of "equal and opposite reaction" without a mass or pressure against another mass? as Rockets in a vacuum will be unique otherwise.

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Re: Does Rocketry Work in the Vacuum?

Unread post by hoi.polloi » Sun Jan 25, 2015 3:45 am

We're back to the beginning again, where it's impossible to test for because a semi-empty vacuum chamber (excepting the test subject) will quickly become filled with molecules ejected.

You'd have to have a very large vacuum chamber and a very small, perfectly analogous, functional model rocket to even come close to a study about perfect vacuum. And even then, could you drop this perfect vacuum from 20 kilometers up to simulate zero gravity?

We could make close tests but not perfect tests. Therefore, the fantastic invention and maintenance of the "outer space rocket" concept is forever locked behind the offices of those who claim to have achieved it. It's a lie protected by scientific impossibility.

If I were the only the person to have an underground base 50 kilometers below the crust, I could make all the claims I want about what magical properties this place has. Then, I would just need to fudge some math so that its phantasy physics perfectly arcs with known mass-testable physics in our biosphere and hey presto! — a believable but purely fantastical story.

What we've at least come up with is the nigh undeniable fact that "rocket science" is a subject that most people think only a few elite are allowed to talk about because they have always been the ones to claim authority to do so while mocking others for asking for better explanation. Thank goodness we armchair physicists can finally have a small platform to make this fact known.

---

If we could get close to these rockets that are so high in security, would we find convincing evidence that they can in fact push against enough mass — not in a hose-like manner, but the perfectly timed explosive manner alleged — rather than merely eject mass to achieve the speeds claimed?

I think, as the point has been made before, it's unnecessary to remind readers that atmosphere and pressure have everything to do with this possibility, since the resistance mass encounters is what makes that mass worthy of any pushing force.

The fact that something appears to move in an equal and opposite reaction is only related to the pushing force on each object, it does not always indicate what is pushing on what.
bounce.GIF
In my above diagram, the yellow arrows indicate forces that aid the rocket in combating gravity. As you can see, its allies grow scarce the thinner the atmosphere it attempts to "climb" by spontaneously generating a ladder. One is reminded of Baron Munchausen pulling himself up by his own bootstraps to explain how a rocket must exert an exponentially increasingly powerful force, after a certain amateur height is achieved, and this power must steadily increase (i.e.; accelerate) all the way to 100 kilometers up and well beyond where balloons are known and observed to quit because of near total loss of atmosphere.

What goes up must come down.

Ever wonder why the convention of science fiction shows is to demonstrate magical means of leaving the planet — ion drive, magic crystals, anti-gravitational forces, artificially induced weightlessness, hover-craft, special undiscovered "radiation", etc.? Oooo, watch the pretty lights ...
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Re: Does Rocketry Work in the Vacuum?

Unread post by Boethius » Sun Jan 25, 2015 4:44 pm

It's my feeling that NASA is lying to me with the "massflow" equation for rocket motion because I can prove to myself experimentally that if it is easier for a force to push down than it is to push up the force will always push down and never push up. And as such the expanding gas in a rocket always pushes down into the atmosphere.

So how does a rocket lift off the ground and fly? My explanation follows. Note that under my claims a rocket cannot travel in space.

Taking a look at the Saturn V rocket with 5 F1 engines used by Apollo 11 we can start to see that "Rocket Science" is, at the core, nothing more than basic physics.

1. According to Wikipedia a mix of Liquid Oxygen oxidizer and RP-1 Kerosene based fuel was used.

2. Taking into account the flow per minute of oxidizer, fuel and their expansion ratios 140,000,000 liters per engine were produced

3. All 5 engines combined produced 700,000,000 liters per minute or 700,000 cubic meters / 25,000,000 cubic feet of gas per minute, almost the volume of the Empire State Building

4. This gas upon expanding would have immediately gone to the area between the nozzle and the launch pad. This is because all forces always move towards the area of least resistance. The rocket offers resistance of 2,800,000 kg/9.8 = 285,000 N

5. In one second (1 sec) the combined Saturn V engines produce 11,666 liters cubic meters of gas. Treating the 5 engines as one, taking the diameter of the Saturn V rocket as 10m, the formula for the cylinder of gas which would be generated underneath the rocket gives us a height of 150m and the gas moving at 150 m/s is equal 540 km/hr. If there was no launchpad the gas would form a perfect cylinder in the first second.

6. If the gas is moving 150 m/s at time=1 second the acceleration is 300 m/s^2

7. Use Newton's 2nd Law as intended: F=MA, convert the weight of the gas expanded to mass
Find the force of the expanding gas to be approx 400,000 N

8. Some of the gas slammed into the launch pad bounces back towards the rocket with 400,000 N force because the mass of the launchpad is infinite and the collision is elastic even through some of the gas billows out into the air forming very nice, showy clouds. Note that most of the molecules bounce back towards the ship because otherwise the volume of expanding gas would completely surround and occlude the ship.

9. The gas bouncing towards the ship after hitting the launch pad meets the next wave of gas coming out of the nozzle and we have a collision of two objects of the same size (gas molecules) traveling the same speed (540 km/h) in which case they exchange velocities; the one coming from this ship goes back towards it and the one from the launchpad returns that way. Eventually, through these collisions, the ship is forced upwards and we have liftoff.

10. What happens once the ship is moving vertically? I haven't done all the research but here's my guess. For a rocket away from the launchpad, the gas expanding out of the nozzle creates a Hydraulic Jump, which is that ring around water being poured into a sink when water moves along the surface until a wave begins to slow down causing the waves behind it to catch it and bunch it up creating a wall of water. The same thing happens with the expanding gas, the leading edge of which slows down due to air resistance and the fact that force decreases as the square of the distance traveled forming a dense cloud of molecules, which the next wave of expanding gas collides with and so forth, once again pushing up on the rocket. This effect should last until the rocket runs out of fuel or the air becomes thin enough so that the hydraulic jump point is far enough away from the ship to be negligible. There are probably equations for this which I may look for at some point.

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