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.
Post Reply
hoi.polloi
Administrator
Posts: 5061
Joined: Sun Nov 14, 2010 7:24 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by hoi.polloi » Sat Jun 22, 2013 6:10 am

I thought it might be pertinent to add one more step to Simon's proposed graduation of rocket chamber pressures.
RocketExpansionDiagram2.JPG
In this model, given the role of theoretical free expansion in the void, gases in the combustion chamber cannot even be pushed to the nozzle, since — by virtue of being in vacuum — they are already headed to the nozzle and interacting with themselves at maximum freedom. Once in the vacuum, they would bounce off one another and go in every direction available, forming billowing clouds of uselessly massed pseudo-gas. Since nothing would be preventing the gas from moving, there would probably not even be measurable swirls on the edges of this instant ever-expanding "cloud".

Even liquid reactions that took place in the combustion chamber that resulted in exploding gases would create gas. This gas would instantly be under the laws of free expansion before they reached the nozzle. Perhaps NASA is hoping the cold of outer space will freeze the gas and cause it to be more effective?

Anyway, work being done on the traditional combustion chamber and nozzle is lost.

Only shooting compressed, extremely dense liquid such as mercury, would move the rocket quickly and effectively in space. And then, how would you get that enormous mass of dense material up into space in the first place?

Ergo, is there no present rocket design that satisfies the required efficiencies of being operational in both atmosphere and void according to this free expansion theory? Well ...
totalrecall wrote: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.
Based on this cheery and optimistic report, perhaps we shouldn't say rocketry is impossible. Maybe we should just say its purpose and functionality should be reconsidered. Water's proven effectiveness according to Heiwa should mean if we pump enough water quickly enough, a rocket that works like the jet board could surpass all previous ineffective and cumbersome models of rocketry. Hell, we could even have geostationary orbiting "satellites" (above places used to rain fail such as England or the Amazon).
rocket_for_outerspace.JPG
You do not have the required permissions to view the files attached to this post.

Heiwa
Banned
Posts: 1062
Joined: Tue Oct 20, 2009 6:20 pm
Contact:

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Heiwa » Sat Jun 22, 2013 6:33 am

hoi.polloi wrote: Water's proven effectiveness according to Heiwa should mean if we pump enough water quickly enough, a rocket that works like the jet board could surpass all previous ineffective and cumbersome models of rocketry.
Not really!
A water jet on a boat just pumps water from the sea and adds some extry energy to the water to create thrust (force) driving the boat.
A propeller (attached to a vehicle) in water or air - when rotated by some engine - creates a thrust (force) to drive the vehicle.
A rocket engine does not pump anything or does not rotate any propeller - it just ejects a mass of hot gases (previously liquid or solid fuel) at high velocity through a nozzle into the environment (gas or vacuum) - which creates the thrust (force) driving the rocket. Doing so the rocket loses mass (the burnt/ejected fuel) and gets lighter and lighter.
I cannot understand that it is so difficult to grasp? Clever USSR rocket and rocket engine designers (assisted by some Germans) managed to build a working model in the 1950's that put a little 80 kg sputnik in very LEO so it crashed a month or so later. USA got nervous and tried to be better. And there we are. It seems we all agree that the French Ariane 5 is the best rocket today (at €150 M a shot to put 16 tons (200 sputniks) in LEO).

hoi.polloi
Administrator
Posts: 5061
Joined: Sun Nov 14, 2010 7:24 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by hoi.polloi » Sat Jun 22, 2013 8:37 am

My ridiculous water rocket above is operating on the ridiculous notion of a pump that is so powerful, and a hose so strong, that it can actually blast off 40 kilometers or more into the air and keep an object hovering because that object does not actually require any fuel on board, it just has to support the incredible pressures of this contraption. I was not talking about existing rockets but proposing a new one based on the jet board. Apparently, my sarcasm was lost in the bad drawings; the inherent superiority of two examples of equal work is in the eye of the beholder, I guess.

But surely, you're not disagreeing with me that (by the physics you believe in and have been describing in this topic) ejecting liquid mass at a high enough velocity and volume could do the same work as gas, given appropriate mechanisms to each? And it would also be the same for solid matter?

Or are you now ascribing a special quality to gas in a vacuum that is the opposite of free expansion, whereby gas does more work in a vacuum than any of gas, liquid or solid do in an atmosphere?

I don't think any of our concepts are that difficult to grasp. That's not the problem. The problem is experimental data to prove each of our predictions.

By the way, your political stories are interesting but sound a bit naive to my ear. Perhaps the 'space race' is another topic that needs your particular world view on. But I guess I am of a more jaded generation?

Heiwa
Banned
Posts: 1062
Joined: Tue Oct 20, 2009 6:20 pm
Contact:

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Heiwa » Sat Jun 22, 2013 10:08 am

hoi.polloi wrote:My ridiculous water rocket above is operating on the ridiculous notion of a pump that is so powerful, and a hose so strong, that it can actually blast off 40 kilometers or more into the air and keep an object hovering because that object does not actually require any fuel on board, it just has to support the incredible pressures of this contraption. I was not talking about existing rockets but proposing a new one based on the jet board. Apparently, my sarcasm was lost in the bad drawings; the inherent superiority of two examples of equal work is in the eye of the beholder, I guess.
Whatever - pumping water from the sea via a long hose to a rocket ejecting the water back to the sea evidently doesn't provide any thrust/force on the rocket, which will never take off. The thrust of the water ejected is balanced by the forces in the hose between sea/rocket.
The water jet on the sea works because the engine on the boat adds energy to the water scooped up and then ejected producing a thrust.
Evidently the engine driving the vehicle must be attached to the vehicle. But do not forget removing and mooring lines when going off with a water jet.
Compare water hose + fire man holding hose and thrust/force pushing fire man back by water ejected from hose. That force cannot be used to drive the fire man to the fire. Rather the opposite. Or not at all depending on the length of the hose.

When a bomb explodes anywhere and the solid low volume gun powder is transformed into great volumes of hot gases due combustion, the hot gases can be used for many things, e.g. killing people, blowing down houses, blowing up enemy, etc, etc, ... and it works also in vacuum. Same basic principle is used in a rocket engine that sometimes even blow up.

hoi.polloi
Administrator
Posts: 5061
Joined: Sun Nov 14, 2010 7:24 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by hoi.polloi » Sat Jun 22, 2013 10:42 am

Heiwa (my bolds) wrote:The water jet on the sea works because the engine on the boat adds energy to the water scooped up and then ejected producing a thrust.
Evidently the engine driving the vehicle must be attached to the vehicle. But do not forget removing and mooring lines when going off with a water jet.
Of course the water is ejected at high volume producing thrust. That's the point of the pump or engine or whatever you want to add energy to the water. Is my English really that incomprehensible to you?

I don't think you can really understand anything I'm saying or else I missed somewhere where you felt attacked and felt the need to re-educate everyone on the most basic premises we've already established. I feel like you are just using every post as an opportunity to rehash the most obvious information instead of trying to sympathize and understand what I'm saying to you. Please, take a break from this thread until you can.
Heiwa wrote:Whatever
Indeed. Dismiss everything I'm saying and talk about whatever is on your mind. Just not in this thread.

Boethius
Member
Posts: 118
Joined: Wed May 22, 2013 12:39 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Boethius » Sat Jun 22, 2013 12:16 pm

A big problem with rockets in space continues to be
how does the gas expelled through the nozzle contribute any force to the system?
when:

1. Free Expansion says gas does no work entering the vacuum

2. The Laws of Gasses say gas can't exist in the vacuum

3. The Laws of Gasses say gas can't do any work in the vacuum

(note that 1., 2. and 3. above all agree with and support each other)

If the gas expelled from the ship in space produces no force how does the ship move?

First, there should be a theoretical reason why I am wrong/mistaken about how gasses work in the vacuum or how they are used by the ship.

Second, there should be reasonable experimental evidence that supports the above theory. Pictures of the Space Shuttle don't count.

Come on Rocketry Forum members / NASA supporters. Show me how I have been mistaken. Can you do this using science? Without strawmen and ad hominem arguments? Let's stick to gasses in the vacuum, please. That's where my doubts stem from.

Why I don't think anyone can answer me: In my opinion, space rocketry is unproven, unscientific conjecture. A fantasy world that has captured the imagination of many and led otherwise rational and intelligent persons to abandon logic and fall under its spell, which is pretty much the story of "advances in science" in the 20th century. Engineering has done pretty well for itself, but science seems to be going backwards.

sceppy
Member
Posts: 67
Joined: Sun Jun 09, 2013 2:39 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by sceppy » Sat Jun 22, 2013 1:39 pm

Space rockets, among other things, are , indeed fantasy, Boethius... and what you say, is correct and a lot of people know this, yet billions don't, because it's the classic magicians trick of people being employed to be the face of bull shit.
Any rational thinking, clear minded, unbiased person who has the ability to push aside peer pressure will know that a rocket can not kick itself up its own arse and fly into the sky, which is what they are being told to accept as gospel truth.

If only space rockets were really hot air balloons with a basket full of cannonballs around a man in a space suit, I could be more persuaded by the arguments that it works and goes higher because the space man is throwing cannon balls out of the basket, until his balloon folds up in no atmosphere that is. :D
It would be akin to seeing Wile E Coyote trying to light a match and blowing it back up as he's falling to his doom. :P

Farcevalue
Member
Posts: 386
Joined: Sat Aug 27, 2011 11:21 am

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Farcevalue » Sat Jun 22, 2013 4:44 pm

Boethius wrote:A big problem with rockets in space continues to be
how does the gas expelled through the nozzle contribute any force to the system?
when:

1. Free Expansion says gas does no work entering the vacuum

2. The Laws of Gasses say gas can't exist in the vacuum

3. The Laws of Gasses say gas can't do any work in the vacuum

(note that 1., 2. and 3. above all agree with and support each other)

If the gas expelled from the ship in space produces no force how does the ship move?

First, there should be a theoretical reason why I am wrong/mistaken about how gasses work in the vacuum or how they are used by the ship.

Second, there should be reasonable experimental evidence that supports the above theory. Pictures of the Space Shuttle don't count.

Come on Rocketry Forum members / NASA supporters. Show me how I have been mistaken. Can you do this using science? Without strawmen and ad hominem arguments? Let's stick to gasses in the vacuum, please. That's where my doubts stem from.

Why I don't think anyone can answer me: In my opinion, space rocketry is unproven, unscientific conjecture. A fantasy world that has captured the imagination of many and led otherwise rational and intelligent persons to abandon logic and fall under its spell, which is pretty much the story of "advances in science" in the 20th century. Engineering has done pretty well for itself, but science seems to be going backwards.
Isn't the atmosphere made up of gases? Oxygen, Co2, Helium, etc. Why are these not sucked into the vacuum of space under the principles of free expansion?

Boethius
Member
Posts: 118
Joined: Wed May 22, 2013 12:39 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by Boethius » Sat Jun 22, 2013 5:11 pm

Farcevalue wrote:
Boethius wrote:A big problem with rockets in space continues to be
how does the gas expelled through the nozzle contribute any force to the system?
when:

1. Free Expansion says gas does no work entering the vacuum

2. The Laws of Gasses say gas can't exist in the vacuum

3. The Laws of Gasses say gas can't do any work in the vacuum

(note that 1., 2. and 3. above all agree with and support each other)

If the gas expelled from the ship in space produces no force how does the ship move?

First, there should be a theoretical reason why I am wrong/mistaken about how gasses work in the vacuum or how they are used by the ship.

Second, there should be reasonable experimental evidence that supports the above theory. Pictures of the Space Shuttle don't count.

Come on Rocketry Forum members / NASA supporters. Show me how I have been mistaken. Can you do this using science? Without strawmen and ad hominem arguments? Let's stick to gasses in the vacuum, please. That's where my doubts stem from.

Why I don't think anyone can answer me: In my opinion, space rocketry is unproven, unscientific conjecture. A fantasy world that has captured the imagination of many and led otherwise rational and intelligent persons to abandon logic and fall under its spell, which is pretty much the story of "advances in science" in the 20th century. Engineering has done pretty well for itself, but science seems to be going backwards.
Isn't the atmosphere made up of gases? Oxygen, Co2, Helium, etc. Why are these not sucked into the vacuum of space under the principles of free expansion?
Gravity holds the atmosphere in place keeping the gasses (as well as you and me) from floating off into space.

simonshack
Administrator
Posts: 6783
Joined: Sun Oct 18, 2009 8:09 pm
Location: italy
Contact:

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by simonshack » Sat Jun 22, 2013 8:30 pm

*


:) As of...
Newton's Third Law of Motion Image

"Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards.
But a push on the water will only serve to accelerate the water. Since forces result from mutual interactions, the water must also be pushing the fish forwards, propelling the fish through the water."


http://www.physicsclassroom.com/Class/n ... /u2l4a.cfm
Therefore, in absence of water, air - or any other adequate reaction force...

AS BELOW - SO ABOVE
Image

No Martini? No party!

sceppy
Member
Posts: 67
Joined: Sun Jun 09, 2013 2:39 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by sceppy » Sat Jun 22, 2013 9:52 pm

Absolutely spot on Simon.
It's one of the reasons why I tell people to understand what atmospheric pressure can do and how it works, because it's just a gaseous liquid like everything above us is.
People underestimate the meaning of atmospheric pressure at sea level of 14.7 psi and think it's nothing, because we walk in it and wave our arms and it doesn't crush us.
What they don't realise is, it doesn't crush us, because we equalise that pressure easily, because our bodies are essentially a denser liquid and also minerals applying the exact same pressure back...but we do suffer the effects of cell break down due to the pressure and it starts with our skin that we notice but it's a pressure on all cells in the body.

I hate being a simplistic genius but I can't help it. :lol:

Air molecules equalise the pressure inside our bodies as to what is outside and it's a case of earth's law of, every action has an equal and opposite reaction.
Newton may have thought it up but the truth is, it applies to "everything" on this earth no matter what.

By the way, gravity does not exist, it's simply air pressure acting on everything but that's another story.
To show how strong atmospheric pressure is, we only have to look at people climbing up buildings using vacuum clamps or window companies carrying huge panes of glass with window vacuum clamps.

People think they suck but it's atmospheric pressure trying to get inside the clamp to equalise the pressure that's inside it, which there is always a small amount of air inside the clamp, as a perfect vacuum cannot be created on earth.
Anyway this may get boring so I'll save that for another time if anyone would like to know all about it in another topic.

Basically, understanding of air pressure by those that believe it to be weak, will go a long way into them understanding how rockets and everything else works on this earth.

arc300
Member
Posts: 166
Joined: Fri Apr 27, 2012 10:13 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by arc300 » Sat Jun 22, 2013 11:10 pm

sceppy wrote: By the way, gravity does not exist, it's simply air pressure acting on everything but that's another story.
I've spent my whole life skirting around the edges of insanity, so I'm perfectly capable of entertaining all manner of seemingly contradictory notions. :) Just one example being the ongoing "The Cold of Space and Our Universe..." thread. If you're game to write more, I'll read it.

hoi.polloi
Administrator
Posts: 5061
Joined: Sun Nov 14, 2010 7:24 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by hoi.polloi » Sun Jun 23, 2013 2:11 am

Please move gravity discussion to: http://cluesforum.info/viewtopic.php?f=23&t=1641

simonshack
Administrator
Posts: 6783
Joined: Sun Oct 18, 2009 8:09 pm
Location: italy
Contact:

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by simonshack » Tue Jun 25, 2013 7:54 am

*

Whereas we may conclude that no motion can be applied to a stationary rocket in a vacuum - this old NASA movie seems to 'prove' that humans do indeed get around when exposed to near-zero pressure ! :lol:

Image

From the Science Channel:

SPACESUIT TESTING
"The instantaneous effects on a human when exposed to near-vacuum conditions"


full link: http://www.youtube.com/watch?v=KO8L9tKR4CY

I, Gestalta
Member
Posts: 149
Joined: Wed Jul 25, 2012 9:00 pm

Re: Why Rocketry Doesn't Work in the Vacuum

Unread post by I, Gestalta » Tue Jun 25, 2013 9:42 am

simonshack wrote:*

Whereas we may conclude that no motion can be applied to a stationary rocket in a vacuum - this old NASA movie seems to 'prove' that humans do indeed get around when exposed to near-zero pressure ! :lol:

Image
Well, I never!

How dare you besmirch the good and wholesome name of NASA with such carnal filth? MODS!

Post Reply