Does Rocketry Work beyond Earth's atmosphere?

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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby Heiwa on Thu Jun 20, 2013 9:02 am

idschmyd wrote:No propulsion without atmosphere. Newton!


So you still do not understand that a propulsion force can be released in vacuum and/or anywhere, e.g. my simple spring? A spring can be mechanical but also in shape of piston with (compressed) gas in it. Release the spring and a force is applied to what is connected to the spring. If my spring is connected to a really solid point with infinite mass, it can move the whole universe connected to the other end of the spring! Imagine that! If the support is not solid, the support will move too. Newton.

If my space ship carries solar panels that in turn can load my spring during travel, it would appear my space ship can go anywhere in space. But I still have to get rid of mass from my space ship to change velocity, when the propulsive force is applied. Space travel is therefore impossible. But you can always apply a force to a space ship.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby idschmyd on Thu Jun 20, 2013 11:36 am

I knew you'd pick up on that - taken out of context it isn't true. Revised headline: No rocket propulsion by means of big fiery blast out the back end like we've all seen on telly in a vacuum. Springs?
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby simonshack on Thu Jun 20, 2013 11:45 am

Heiwa wrote:
idschmyd wrote:No propulsion without atmosphere. Newton!


So you still do not understand that a propulsion force can be released in vacuum and/or anywhere, e.g. my simple spring?


Sigh...The "spring theory" is yet another worn-out canard/parable relentlessly rehashed by NASA nerds to 'explain' how rockets work in the void of space, much like the "gun/bullet or firehose recoil theory" and the "medicine ball thrown from wheeled office chair" - we've heard them all before, thank you very much. I'd rather not see further vapid NASA moonshine being posted and diffused on this forum, Heiwa. Please.

I am posting this video halfheartedly - with a Parental Advisory warning: do not show this to your kids!

full link: http://www.youtube.com/watch?v=L0AMQ6kRNMA

I hope you did understand / approve my graphics (THE POWER OF AIR) and reasonings on the previous page of this thread - all respectful of Newton's laws, yet not fully addressed by the same. I dare trust you won't wish to disprove the well-known aerodynamic fact that (the REACTION of) air resistance increases exponentially with (the ACTION of) speed/motion. See, the NASA boys claim that air/atmosphere has NO role whatsoever in propelling their rockets. Is this your contention too? I understand that this thread discussing whether or not rockets may work in the vacuum of space seems to be an annoyance to you for some reason. You recently called for this thread "to be locked ASAP!" This will not happen anytime soon - and certainly not on the grounds of your adamant belief in rocket propulsion in vacuum - which appears to be shared by a scant minority here.

Correct me if I'm wrong, but I have a feeling that your puzzling, double-edged and rather nebulous stance aims at ultimately upholding the existence of man-made satellites in low earth orbit - while dismissing, on the other hand, the feasibility of long-distance space travel. If so, please make yourself clear now and spit it out: stop parroting age-old NASA twaddle on this thread and make your case for satellites - on our dedicated discussion forum:
"Satellites : general discussion and musings"> viewtopic.php?f=23&t=1070&start=540
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby Boethius on Thu Jun 20, 2013 11:47 am

Heiwa wrote:
Boethius wrote:
Same goes for a ship in space. You can combust all the gasses you want. If you don't generate an external force you're not going anywhere. People say "the ship is pressing on the gasses" but the gasses don't exist outside the ship. Gas doesn't exist in the vacuum. So the ship is left pressing against itself. A space ship is like a car with an engine but no wheels.



Imagine a ship in space consisting of two parts A and B each with mass m. Thus the space ship A+B has mass 2 m. The space ship has a little internal mechanism, e.g. a spring, that can eject part A away from the space ship at velocity v leaving space ship B alone. When the mechanism is activated and applies a force on part A, space ship B gets velocity -v.


Strawman coming: rockets do not use springs to eject solids. They propel gasses.

Heiwa wrote:Newton, you know.


magic wordspeak = Newton

Let's evaluate your Calling on Newton

1. Newton didn't consider gasses, only solids. The gas/chemistry pioneers like Joule, Thompson, Boyle and others generated results which disagree with rocketry. That's why NASA types keep going back to Newton in the 1600's instead of going forward to Joule in the 1800's.

2. Newton's 3rd Law, equal and opposite forces, action/reaction, only applies if you have the necessary net external force. An object can't move itself. Not understanding or ignoring this principle leads to a misapplication of Newton.

3. Newton's 2nd Law, Force = Mass x Acceleration only applies if the ship is already accelerating (changing velocity) when its mass is reduced.

4. You don't specify which Newton you are going for, 2nd Law, 3rd Law, both?

5. NASA folk only seem to know Newton as far as NASA wants them to. For instance completely ignore the fact that gasses are not solids and that a different set of equations are used to evaluate the work done by and forces generated by gasses.

Continuing on with the Strawman
You've described a rocket that uses a solid propellant and now, of course, you'll switch it to using gasses without any consideration of the different physical properties of a gas or the fact that gasses are undefined in space. Nearly 200 years of gas/chemistry research in the vacuum nullified by NASA without any reason given except, trust us, we're scientists.

Heiwa wrote:I can evidently replace my mechanical spring by a liquid that burns producing a hot gas that ejects part A. That's why my space ship works in vacuum.


Strawman complete The difference between gas and solid is ignored.

Let's just say...this may be your blind spot in the analysis...

You cannot eject gasses into space. Why not?
Because free expansion states that no work is done by a gas entering a vacuum.
Ejecting something requires work.
If the gasses do no work in space they cannot help move the ship once they enter space.
So the only force available to move the rocket are the accelerated gasses in ship itself which cannot move it because it is not a net external force (proper application of Newton's 3rd Law).

Heiwa wrote:Problem is that I have to get rid of part A every time I want to change velocity so my space ship gets smaller and smaller in the process.


This is another misapplication of Newton
Force = Mass x Acceleration only works if you are already accelerating. If Acceleration = 0 then Force = 0 no matter how much Mass you release.

In space, when you release exhaust gas, that gas is just going to drift away. Yes, the gas will drift away very, very quickly, at many km/s but it's still just drifting off. It's not pushing the rocket because it imparts no force. Acceleration = 0, Force = 0.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby Heiwa on Thu Jun 20, 2013 3:11 pm

simonshack wrote:Correct me if I'm wrong, but I have a feeling that your puzzling, double-edged and rather nebulous stance aims at ultimately upholding the existence of man-made satellites in low earth orbit - while dismissing, on the other hand, the feasibility of long-distance space travel.

Yes, I think the French Ariane 5 is feasable to put a 12 ton satellite in geostationary Earth orbit, GSEO, and vacuum using about total 700 tons of fuel costing €150M per shot. It is made in two steps - first you get into LEO using the main rocket and then the satellite is pushed up to GSEO using a smaller rocket - that works in vacuum. And hopefully Ariane 6 will put a 7 ton satellite there at much reduced cost 2020. But that's the end of space exploration in my view.
The reason why rockets work in vacuum is that the mass of solid or liquid fuel in a tank is transformed/burnt into the same mass of very hot gas taking much more space that can be ejected from the rocket at very high velocity into vacuum via a nozzle. The resulting thrust propels the rocket that, e.g. carries an Ariane 5 satellite, from LEO to GSEO. Newton.
The NASA/SPACEX/JPL suggestions of Moon and Mars travel are evidently 100% nonsense as you cannot carry the required mass of fuel to complete the voyage or even get away from Earth gravity. Same with the US space SHUTTLE. It was much too heavy from the start ... and only empty mock-ups were sent away to disappear somewhere and impress stupid observers. The SHUTTLE seen landing on Earth a week later was just dumped from an airplane a little earlier. The 100 tonnes SHUTTLES never reached LEO (or the ISS) because for that you needed five or more Ariane 5s to get there, which the US didn't have. So the ISS is 100% hoax.
I assume the same airplane was used to drop off the Apollo modules allegedly coming back from the Moon 1969-72 at 10 000 m altitude, so they could splash into the Pacific carried by a parachute. Hollywood style.
Only the Ariane 5 works. :D So no cute girls are required to wave off the Ariane 5s in videos of the blast offs. :(
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby simonshack on Thu Jun 20, 2013 7:31 pm

*

40 MILLION HP
The Wondrous Power of Air

I woke up this morning wondering: "how much horsepower would a Porsche Carrera sports car (which is shaped a bit like a rocket plume) need to reach a speed of 16.000km/h (4.4km/s) in our atmosphere?" Remember, that's the velocity at which hydrogen/oxygen propellant is ejected from a rocket nozzle.

To my delight, I found a handy Drag Coefficient/to Horsepower calculator. It basically calculates for you how much horsepower a given car (with a given Cx /aerodynamic drag - and a given weight) would need to reach a given speed. Wonderful! This calculator was just what I was looking for:
http://www.wallaceracing.com/Calculate% ... 0Speed.php

I then looked up the drag coefficient of a Porsche, and found it here : the Cx of a Porsche is 0.3. For the frontal area of the car, I used the figure of 20 Sq/Ft - which I found here. Ok, so it's that of a Chevrolet Corvette - but it should be pretty similar to that of a Porsche. It also approximately matches the stated area of a Space Shuttle main engine nozzle:

Image
http://en.wikipedia.org/wiki/Space_Shuttle_Main_Engine

Then, I looked up the weight of a Porsche Carrera, and found that it is 3230lbs. But I decided to 'cheat' a little, and went with the weight of the larger Porsche Cayenne (4400lbs- or 2000kg) - since it perfectly matches the weight of the fuel mass claimed to be released every second* by large rockets such as Ariane and the Space Shuttle.

*(To be sure, a horsepower unit is defined as a force produced over one second of time. One metric horsepower, for instance, is the power needed to raise a mass of 75 kg against the earth's gravitational force over a distance of one metre in one second).

So, these are the figures I inserted into my wonderful calculator:

Drag coefficient: 0.3 (Cx of Porsche Carrera)
Frontal area of car (think rocket nozzle area): 20Sq/Ft)
Weight of car (think fuel mass ejected per second): 4400Lbs(2000kg)
Velocity of car (rocket exhaust velocity of 4,4km/s): 9941mph (16.000km/h)

Here's what the calculator came up with:

Image

40.239.275 HP - or roughly 40million HP ! Wow! it certainly looks like the REACTIVE FORCE of air, fighting the ACTIVE POWER of a car travelling at hypersonic speeds produces an awful lot of resistance/ counter-power! I honestly didn't think it would amount to as much as 40million HP. But then again, NO Porsche - nor any car - can go as fast as 16.000km/h...
^ NOTE that the rolling resistance (1,516) is absolutely negligible in comparison to the colossal force of AIR. ^

Image

So finally, I decided to look up how much horsepower NASA claims the Space Shuttle engines produce...and... LO AND BEHOLD ! - it isn't far off my above, approximated figure of "40million HP"! Here's from the official NASA website:

"The engines' exhaust is primarily water vapor as the hydrogen and oxygen combine. As they push the Shuttle toward orbit, the engines consume liquid fuel at a rate that would drain an average family swimming pool in under 25 seconds generating over 37 million horsepower."
http://www.nasa.gov/returntoflight/syst ... _SSME.html

Or, if you prefer:
Standing about the same height as the Statue of Liberty but weighing three times as much,
the two white Solid Rocket Boosters ignite in anger and push out a combined 6.6 million pounds of thrust (equivalent to 44 million horsepower.)

http://www.roadandtrack.com/special-rep ... our-ov-105


So I guess we can now tranquilly say - without fear of sounding stupid or ignorant - that rockets do indeed push against air - or rather - air pushes against the rockets to propel them up through our atmosphere. Yet, one mystery remains: NASA claims that their rockets reach speeds of 8km/s - almost DOUBLE the 4.4km/s exhaust velocity. Yet, NASA clearly states that their rockets LOSE efficiency as they reach higher altitudes. They even have a name for it: "UNDEREXPANSION":

Image
Source of original rocket nozzle over/under expansion diagram: http://en.wikipedia.org/wiki/Rocket_engine

Oh well, that's NASA for you I guess... In any case, it should be obvious that when air/atmosphere gradually thins out and eventually goes missing altogether(vacuum), no more counter-force (as of Newton's laws)is available for the rocket to keep ascending. Much like a dolphin jumping out of the sea - and briefly flying before gravity brings it plunging back into its own, denser fluid for which it was 'designed for'. Just like a rocket attempting to leap into the void of space.

****
An interesting article about aerodynamic drag: http://phors.locost7.info/phors06.htm
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby simonshack on Thu Jun 20, 2013 8:33 pm

Heiwa wrote:Only the Ariane 5 works. :D So no cute girls are required to wave off the Ariane 5s in videos of the blast offs. :(

Allright, Heiwa.

So only ESA's Ariane5 works. While NASA has been fooling the world with their bullcrap for half-a-century.

Yeah - makes perfect sense... Vive la France! :rolleyes:
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby totalrecall on Fri Jun 21, 2013 4:58 pm

I just lost a big long post due to letting my reply sit on the computer for too long. Ok, second attempt.

I've just been on holiday for 2 weeks doing nothing so my brain is fried. I left this thread at page 14 and have read up to page 16, so I may have missed something important.

I am with heiwa and lux on this one. If you look at the flyboard video from 05:18 to 05:21, you will see the man attempting to fly up further than the water cable allows. If it hadn't been for the weight of the jet machine and lack of water to pump, the man would have flown up high in the sky.

Image

Secondly, I don't think a rocket pushes against the air underneath it to cause it to rise. A firework rocket has little air under it to push against when it is several meters high, especially compared to the several tons of air pushing down on it from above. Rocket propulsion must use another method.

Perhaps the ultimate questioning should be along the lines of "What is movement?", "What causes movement?", "Is there a common source behind all movement?". These are question about perception and reality and are not for the topic of this thread. It would be interesting to research it nevertheless.

Lastly, we all must be careful when using theory to try and define reality or possible reality. Recently, not related to this topic, I have been looking into why an airplane flies and why light refracts in a denser medium. Surprisingly when delving deep into the subject I found that nobody knows the answer for sure, even physicists. There are plenty of guesses on the physics forums, some good ones IMO, but again nobody really knows.

Observation and experimentation are the only real tools we have for perceiving reality correctly, and this rocket subject obviously doesn't allow that. We know when we do x, y happens, and engineers have developed mathematical formula to predict the outcome based on these past experiences. But maths can't tell us why something happens, nor foolproofly predict the outcome when another variable is involved, such as vacuum as a medium.

Therefore I don't think I will ever be able to know whether a rocket travels in a vacuum due to my own theories on how a rocket may work.

Theory is schmery after all.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby Flabbergasted on Fri Jun 21, 2013 5:34 pm

totalrecall wrote:If it hadn't been for the weight of the jet machine and lack of water to pump, the man would have flown up high in the sky.

A firework rocket has little air under it to push against when it is several meters high, especially compared to the several tons of air pushing down on it from above. Rocket propulsion must use another method.

I have been looking into why an airplane flies [...] I found that nobody knows the answer for sure, even physicists.

I've just been on holiday for 2 weeks doing nothing so my brain is fried.


I was going to write something in response, but by your own confession I see it won´t be necessary. :)

No offense, totalrecall. Your comments on theory vs. perception of reality are interesting.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby Boethius on Fri Jun 21, 2013 6:32 pm

totalrecall wrote:Lastly, we all must be careful when using theory to try and define reality or possible reality. Recently, not related to this topic, I have been looking into why an airplane flies and why light refracts in a denser medium. Surprisingly when delving deep into the subject I found that nobody knows the answer for sure, even physicists. There are plenty of guesses on the physics forums, some good ones IMO, but again nobody really knows.

Observation and experimentation are the only real tools we have for perceiving reality correctly, and this rocket subject obviously doesn't allow that. We know when we do x, y happens, and engineers have developed mathematical formula to predict the outcome based on these past experiences. But maths can't tell us why something happens, nor foolproofly predict the outcome when another variable is involved, such as vacuum as a medium.


This is the essence of science. You don't really know until you run the experiment. Until then all you have are hypotheses.

As far as I can see nobody, not even NASA, has ever run a serious space rocket experiment. Where are the zero-gravity vacuum chambers big enough to fly rockets? There's a 17-mile long supercollider but the largest vacuum chamber is 120 feet.


totalrecall wrote:Therefore I don't think I will ever be able to know whether a rocket travels in a vacuum due to my own theories on how a rocket may work.
Theory is schmery after all.


And nobody can ever go out and investigate NASA claims around rockets in the vacuum independently of NASA.

Space science is like a cult run by ancient priests who speak to the Gods in private. We're not supposed to think for ourselves. We only wait until the NASA oracle tells us the great truths divulged only to them. This is not how science, nor modern, information-based, educated society is supposed to function. The goal of education is for us to learn how to figure things out for ourselves; to examine, to evaluate and to reason with the facts and data. What good is that training if, in the end, we can only shut up and believe what we are told with no proof, no solid theory behind it and no way to check the results or repeat their experiments ourselves?

Rocketry is not unique in this regard. Pretty much all the big results in science follow this pattern. Anyone who challenges the status quo is labeled an "idiot" or a "religious nut" which is ironic because science is behaving more and more like a religion based on faith and less and less of a method based on observation.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby totalrecall on Fri Jun 21, 2013 9:53 pm

Boethius wrote:And nobody can ever go out and investigate NASA claims around rockets in the vacuum independently of NASA.

Space science is like a cult run by ancient priests who speak to the Gods in private. We're not supposed to think for ourselves. We only wait until the NASA oracle tells us the great truths divulged only to them. This is not how science, nor modern, information-based, educated society is supposed to function. The goal of education is for us to learn how to figure things out for ourselves; to examine, to evaluate and to reason with the facts and data. What good is that training if, in the end, we can only shut up and believe what we are told with no proof, no solid theory behind it and no way to check the results or repeat their experiments ourselves?

Rocketry is not unique in this regard. Pretty much all the big results in science follow this pattern. Anyone who challenges the status quo is labeled an "idiot" or a "religious nut" which is ironic because science is behaving more and more like a religion based on faith and less and less of a method based on observation.



I couldn't agree more. I'm often finding that the 19th century was the last time experiments were conducted which produced results going against our esteemed priests' doctrines. They locked down science pretty well after that.

This forum is like a renaissance of 19th century reason. We're doing a good job at calling out their bullshit. The next step is doing a few experiments of our own perhaps. Thank goodness for the internet.
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby brianv on Fri Jun 21, 2013 10:10 pm

totalrecall wrote:
Boethius wrote:And nobody can ever go out and investigate NASA claims around rockets in the vacuum independently of NASA.

Space science is like a cult run by ancient priests who speak to the Gods in private. We're not supposed to think for ourselves. We only wait until the NASA oracle tells us the great truths divulged only to them. This is not how science, nor modern, information-based, educated society is supposed to function. The goal of education is for us to learn how to figure things out for ourselves; to examine, to evaluate and to reason with the facts and data. What good is that training if, in the end, we can only shut up and believe what we are told with no proof, no solid theory behind it and no way to check the results or repeat their experiments ourselves?

Rocketry is not unique in this regard. Pretty much all the big results in science follow this pattern. Anyone who challenges the status quo is labeled an "idiot" or a "religious nut" which is ironic because science is behaving more and more like a religion based on faith and less and less of a method based on observation.



I couldn't agree more. I'm often finding that the 19th century was the last time experiments were conducted which produced results going against our esteemed priests' doctrines. They locked down science pretty well after that.

This forum is like a renaissance of 19th century reason. We're doing a good job at calling out their bullshit. The next step is doing a few experiments of our own perhaps. Thank goodness for the internet.


Who was it wot said : "The art of thinking and reasoning in strict accordance with the limitations and incapacities of human misunderstanding." ?
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby iCONOCLAST on Fri Jun 21, 2013 10:15 pm

Ambrose Bierce
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby brianv on Fri Jun 21, 2013 10:18 pm

iCONOCLAST wrote:Ambrose Bierce


Giggle perchance? :P

edit: BTW The question was a rhetorical one!
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Re: Why Rocketry Doesn't Work in the Vacuum

Unread postby Flabbergasted on Sat Jun 22, 2013 3:37 am

totalrecall wrote:I'm often finding that the 19th century was the last time experiments were conducted which produced results going against our esteemed priests' doctrines. They locked down science pretty well after that.

This forum is like a renaissance of 19th century reason. We're doing a good job at calling out their bullshit. The next step is doing a few experiments of our own perhaps. Thank goodness for the internet.


A topic for another thread, but, yes, I think you are right: around or just after the turn of the century, a number of scientific disciplines were "locked down" through the adoption of paradigms to which all future research would have to conform. Anthropology and archeology are particularly gross examples. These paradigms have since served as "knowledge filters", preventing alternative world views and a lot of solid facts and findings from being evaluated, published and discussed by researchers and laymen alike.
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