Does Rocketry Work beyond Earth's atmosphere?

[Heiwa]

Simon - the water jets applied to the feet/hands of the flying person only apply forces on the feet/hands to keep the person aloft or flying away sideways. The sea below has nothing to do with it. It could have been a concrete floor but ... it is safer for the person to splash down into the water.

[rusty]

Looks like you're having fun here. This will not do!

So let me just chime in and add my two cents. First of all: Yes, we can't know for sure until we test it! That applies generally and to all topics. But as we can't test any of the assertions made in this thread, all we can do is to make educated guesses. So here are mine. And thanks to Boethius for bringing up this topic. I'm more in the hoi/boethius camp on this one - rockets may work only somewhat in vacuum, but never to the extent that NASA claims.

One of the misconceptions i came across is the assumption, that throwing out a chunk of material must have the same effect as propelling out the same mass in gaseous form ("helium atoms"). That's the difference between theory and practice. In theory, it's the same. But in practice, it makes a huge difference, simply because it's impossible to propel out a gas in the same way as some fixed stuff. That's what "free expansion" is about - I don't think of it as some sort of esoteric law of physics, but simply as a logical consequence of breaking up matter into a gas and the way it behaves both in vacuum and in the presence of other gases (atmosphere).

Please note also, that a jet engine works quite differently - it's more like a very fast propeller, if I understand it correctly.

What's more, the thrust a rocket produces is NOT caused by the sheer mass/velocity of the expelled gas. The mass of the consumed gas in any instant of time is absolutely minimal compared to the mass of the whole thing (rocket + fuel). Think about standing on your skateboard with a bag full of tennis balls. Would you think that throwing the tennis balls could make you drive through your hometown? Not even if you'd shoot them with some kind of cannon, I'd say. Maybe you move a tiny little bit in this case.

Probably the propulsion of a rocket in atmosphere boils down mainly to the pressure of the gases. If there's nothing to press against (in vacuum) it would not work.

To Simon's "Red Bull Challenge": I think in theory it could work if the forces were strong enough. But in practice it won't since the forces aren't. Plus, it would be impossible to control the whole thing, to keep it in balance. But I agree with Heiwa/Lux that it doesn't matter much if the person is 3m or 30m above the surface, as both is too far away to truly interact with the water in the sea/lake and the force is too weak in any case. My guess what happened in this video is that the initial momentum created when the guy was still in the water caused him to lift off the surface. Subsequently, the force was to weak to sustain his flight, plus it got out of control. It's probably that simple.

[Flabbergasted]

...it doesn't matter much if the person is 3m or 30m above the surface, as both is too far away to truly interact with the water in the sea/lake and the force is too weak in any case. My guess what happened in this video is that the initial momentum created when the guy was still in the water caused him to lift off the surface. Subsequently, the force was to weak to sustain his flight, plus it got out of control. It's probably that simple.

Not what I see in this video at 0:33 and 0:51 and 1:05 and 2:15, and very clearly at 5:04.

full link: http://www.youtube.com/watch?v=lM8kEHjQz9U

[hoi.polloi]

Simon - the water jets applied to the feet/hands of the flying person only apply forces on the feet/hands to keep the person aloft or flying away sideways. The sea below has nothing to do with it. It could have been a concrete floor but ... it is safer for the person to splash down into the water.

I think we are using the term 'nothing to do with it' a little erroneously. The sea is the level upon which the forces of the water plumes first build acceleration against gravity.

But I agree we should be talking about force. Let's please get back to discussing gas and free expansion and whether an ejected gas at any speed would match the force of an ejected liquid — in particular under the conditions NASA claims are those in which its rockets operate.

[Heiwa]

The sea is the level upon which the forces of the water plumes first build acceleration against gravity.

No, the water jets only apply forces on the feet/hands of the person flying away.

Compare fire hose!

[Boethius]

2. Objects don't accelerate unless they exchange energy with some other object/field. There are no objects or fields in space (I regard them to be so small/weak as to be virtually non-existent)

Dear Boethius,

I believe we are saying the exact same thing - only expressing it in different manners.

This is the absurd subversion of Newton's laws which NASA has sold to the public for decades:

"The rocket fuel (Force A) pushes against its own, vaporized self( Force B ). This force alone is what enables our rockets to attain the required 27.000km/h escape velocity which places them in orbit - and out of reach of Earth's gravity pull. Thereafter, no more fuel is needed and the rockets can be switched off - as the spacecraft is now safely free-falling, a bit like the moon orbiting our planet yet never falling down on us, you see?"

I'd say that burning that fuel will certainly expel it from its tank - but it wouldn't make any heavy rocket / spacecraft move upwards at any significant rate once the outside pressure reaches zero - or thereabouts.

*****************

Hello Simon,

I believe we are saying the same things...

they fool people the same way you do with a "proof that 1=0". They use valid laws in invalid situations. And of course they patrol the Internet and media calling anyone who challenges them an idiot, anyone who pressing them on details as someone who just doesn't get it.

If there's no way for a rocket to do work with the forces it generates then all the arguments about expelling gas, changing mass, conservation of momentum, massflow, Newton's Laws et. al. are moot. Remember, rooster's don't lay eggs.

[Boethius]

Here's some more info on the pioneering experiments of the good Doctor Robert Goddard, one of the founders of rocketry:

March 16, 1926 Goddard conducts the first successful flight of a liquid fueled rocket. The only problem is that he didn't film it. Even though he brought along a film crew. The excuse is that they ran out of film before the rocket took off.

Goddard was head of the Clark University Physics Department, head of their Physics Laboratories and sponsored by the Smithsonian. And he didn't have enough film in the camera to film a 3 second flight? What were they there to film?

I went to youtube to see if I could find film of any of his flights and there is a 2 hour video of Goddard's greatest moments and as far as I can see in that incredibly boring 2+hour video that I haven't watched to the end none of his rockets ever flew.

No wonder he said rockets would work better in space. His rockets worked terribly on earth.

http://www.todayifoundout.com/index.php ... ed-rocket/


full link: http://www.youtube.com/watch?v=Pq7WmrTbi-Q

[arc300]

[...] would this "Redbull Challenge" be at all feasible - providing the exact same thrust as the Flyboard emits over the sea surface? Simple, straightforward answers, please.

-Yes
-No
-If yes, why?
-If no, why?

Gut feeling would tell me, 'No.' And since reading Boethius's interesting argument I really think I'm starting to understand why my gut tells me that.

2. Objects don't accelerate unless they exchange energy with some other object/field.

At or near sea level where the air is dense, exchanging energy with some other object, ie. the sea or air molecules, is like shooting fish in a barrel. A larger proportion of the ejected water molecules can be expected to collide with the local air molecules and thereby do some useful work, resulting in an initially powerful upward thrust.

Other posters have alluded to the water jet needing more thrust at higher altitude. I agree. More thrust here must mean more water being ejected, and probably at a higher velocity. Why? To maximise both the chance of each water molecule colliding with (doing work) the increasingly rare air molecules and, for each increasingly rare 'hit', to maximise the amount of work done.

When I first read Boethius's first posts, I thought that this topic 'Rockets Don't Work in a Vacuum', if true, would be equally as powerful as 'Hollow Aluminium Wingtips Can't Cut Through Hardened Concrete and Steel', or Heiwa's 'The Smaller Weaker Top Part of a Building Can't Crush the Larger, Stronger Bottom Part'.

Of course, I could be wrong, but what the hey? It wouldn't be the first time.

[hoi.polloi]

No, the water jets only apply forces on the feet/hands of the person flying away.

You're pulling my leg.

Of course the water jets only apply direct forces on the person where they meet, but the other end of the jets are impacting the surface of the sea. I know that you are not trying to tell me that the only thing that matters in keeping this person aloft is the person and their water toy, but the entire Earth and its oceans should be discarded — notwithstanding the ocean being the very source of the water and the gravity being the thing preventing them from soaring upwards, et cetera, etc.

So I am not sure why you are trying to argue about a closed system of a person-and-their-jet-pack.

If you are, you need to pull a Bill Clinton and be more specific about what you mean by the "it" in your phrase "the sea has nothing to do with it".

[simonshack]

*

WHY ROCKETS WON'T WORK IN THE VACUUM OF SPACE



Having done some further homework on this matter, I will now expound what is possibly the main reason why NASA is constantly lying to us about their space exploits. No, I do not claim to be a rocket scientist - far from it - but I have come to a personal conclusion that it is physically impossible for any man-made rocket to be propelled in the (near)vacuum of outer space.

Although I will intentionally illustrate this conclusion in very simplified manner, hopefully accessible even to a 5th grader, I trust that anyone with any higher degree of qualifications will at least appreciate the sound logic of my layman's reasoning. To be sure, only NASA has large enough vacuum chambers to perform any sort of experimental verification of what I'm about to contend. So with no further ado, let me start off by reminding everyone just what tremendously powerful and seemingly 'magical' forces vacuum can 'produce' here in our Earth's atmosphere.


THE MAGDEBURG HEMISPHERES experiment (1654)

Back in 1654, Otto Von Guericke, the inventor of the air pump (to simulate vacuum on Earth) performed a spectacular experiment. He had 16 horses trying to pull apart (in vain) two empty hemispheres held together only by the force of vacuum:



QUOTE - from a scientific CERN article:

"By this experiment he demonstrated that it is impossible to pull the two halves apart against the air pressure, even by using 2 X 8 horses (the counter-pressure by air in the interior of the sphere is missing). During this time, it became clear that we are living on the bottom of a huge ocean of air and that the mass of the atmosphere corresponds to a pressure of about 1kg per cm² or 10 tons on an area of 1m². The reason why we don’t feel anything of this tremendous pressure is simply that there is the same pressure inside our body." http://www.cientificosaficionados.com/l ... 1-CERN.pdf

Indeed, folks: we are living on the bottom of a huge ocean of air - and that is something we all tend to forget. Imagine that: "10 tons on an area of 1m²". Pretty heavy stuff, huh? Draw a big breath of air and you'll feel it! Of course, this air surrounding us (our atmosphere) has a certain density. And so has, for instance, water. And so has vacuum. So let's take a look at this table, at present. I have highlighted in blue the densities which are of interest to us right now:


To visualize these differences in DENSITY in a more comprehensible / intuitive way :

1 (water)
0,001 (air) > or 10^-3
0,000000000000000000000001 (vacuum in space) > or 10^-24

As you can readily see, the two densities that NASA's rockets supposedly traverse as they rise up to the skies are hugely different.

(Just to put all this into perspective, on the other side of the spectrum we see that a "black hole" - considered by scientists as the highest imaginable pressure known to mankind - is 10 ^+27. In other words, one could say that the density gap/difference between VACUUM <vs> AIR is almost as large as the difference between WATER <vs> "BLACK HOLES". Food for thought, anyway.)

Now, remember: NASA tells us that their rockets perform below max efficiency at sea level, at optimal efficiency somewhat higher in the atmosphere (as the rocket pressure equalizes with the external air pressure) and then start losing efficiency again as they ascend into ever thinner air. Note: NASA says so - not me. http://www.septclues.com/SPACE_STATION/ ... agram1.jpg

But the BIG question is: just HOW MUCH power would a rocket lose as it enters into near-vacuum?

Well, consider this: no honest scientists will deny that, when opening a valve between two containers (one containing air at high pressure - and the other only vacuum) the pressures in the two containers will equalize in a fraction of a second, the vacuum container 'sucking' the air to itself with tremendous, almost explosive force. (see the above density figures to understand why.)

Imagine now the high pressure emitted by any rocket from its (always open) nozzle. As it enters the vacuum of outer space, the very same - almost explosively rapid - pressure equalization is bound to occur. The rocket will be emptied of all of its pressurized fuel in a flash - by the overwhelmingly superior power of the vacuum itself. No matter how powerful the rocket (propelled by any fuel known to man / and designed to perform in our 0,001 atmosphere) - the very laws of physics will not allow it to ascend any further into the void of space. It will haplessly tumble back to Earth.

This insurmountable 'little problem' may have been understood back in the heydays of early rocket research - thus paving the way for the ridiculous NASA circus and its clowns to take over and explore exploit outer space ... financially.


Addendum

Adding to the above-mentioned 'little problem', is the fact that rockets do indeed push against our relatively dense atmosphere (see the above 0,001 figure). Naturally, NASA will tell you otherwise - and this is one of their most infamous lies. They will cite Newton and repeat ad nauseam that their rockets' forward motion is due solely to recoil reaction forces - and that aerodynamics / air pressure have nothing do with propelling them - at all ! This is of course absurd and is akin to say that water has nothing to do with a rowing boat's forward motion. You need not be a genius to figure that it is the oars pushing the water backwards that make a rowing boat move forwards (NASA would basically rebut that it moves exclusively due to the rowing man's rocking motion - and that the oars' water displacement has nothing to do with propelling the boat !). Of course, if you raise the oars out of the water (density 1) and just flap the oars in the air (density 0,001), you won't go very far. Likewise, a rocket that works fine in our atmosphere (density 0,001) will obviously not go very far once the atmospheric density drops to 0,000000000000000000000001 !

[Boethius]

Imagine now the high pressure emitted by any rocket from its (always open) nozzle. As it enters the vacuum of outer space, the very same - almost explosively rapid - pressure equalization is bound to occur. The rocket will be emptied of all of its pressurized fuel in a flash - by the overwhelmingly superior power of the vacuum itself. No matter how powerful the rocket (propelled by any fuel known to man / and designed to perform in our atmosphere) - the very laws of physics will not allow it to ascend any further into the void of space. It will haplessly tumble back to Earth.

This insurmountable 'little problem' may have been understood back in the heydays of early rocket research - thus paving the way for the ridiculous NASA circus and its clowns to take over and explore exploit outer space ... financially.

Hello simon,

fyi gas enters a vacuum at about 2,000 m/s (depends on the gas of course). So, as you point out, you're not going to get much thrust in space out of the 12 meter nozzle of an F1 engine in a Saturn 5 rocket. A molecule of gas that enters the nozzle is off into space in thousandths of a second.
http://adsabs.harvard.edu/full/1953ZA.....33..251K

I've been thinking about the pressure issue regarding space travel. As it turns out boats, planes and rockets (in the atmosphere), the 3 miracle machines of the modern age, all count on air pressure.

Metal boats float because of buoyancy, the pressure of the water below the hull is greater than the air pressure inside.

Planes fly because of lift, the pressure under the wing is greater than above.

All rockets equations have a thrust component which measures the pressure of the expelled gas.

Take away pressure (e.g. in the vacuum of space) and none of these three machines will work. Taking away pressure is like dividing by 0 in a math proof. Once you do it your answers are invalid even if you follow all the rules the rest of the way.

[Lazlo]

WEIRD FIND

Weird online mag. While the front page is funny/quirky, check out page two: the Siemens rocket advert.

https://www.google.com/search?q=siemens ... e&ie=UTF-8

It won't let me hot-link

Pick the link that says "GOVERNING Magazine March 2013"

[Maat]

WEIRD FIND

Weird online mag. While the front page is funny/quirky, check out page two: the Siemens rocket advert.

https://www.google.com/search?q=siemens ... e&ie=UTF-8

It won't let me hot-link

Pick the link that says "GOVERNING Magazine March 2013"

PDF: http://chcconnections.com/reports/GOV_M ... 5B1%5D.pdf

Screenshots:

moon-cover-Governing-mag.jpg (85.19 KiB) Viewed 12003 times

SpaceX-Siemans-ad.jpg (126.44 KiB) Viewed 12003 times

[Lazlo]

Thanks Maat!

That is just too weird! If they're not having us on I don't know what.

L.

[simonshack]

*


SIEMENS - the experts in 'virtualization'
http://www.usa.siemens.com/industrial-p ... ivity.html

Lazlo, that was mighty interesting.

A few gems from the above-linked Siemens page:

"From the increasing use of virtualization to outside-in manufacturing principles, public and private sector organizations alike are finding new ways to innovate, grow and prosper."

"Turning virtual into real and skeptics into believers
Siemens is helping leading companies explore new places in new ways. The engineers at SpaceX knew that successfully launching a rocket was contingent on millions of things going right. Just a single error could impact the entire mission to the International Space Station. To help solve this challenge, they turned to Siemens industry software. This played a critical role in enabling the SpaceX team to design and test products virtually before constructing them physically — optimizing the chances of a successful launch."

So I guess that "virtualization" is the name of the game - the 'keyword' to the phony space industry.

******
ps: I have added an addendum to my above post.