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Old 17th April 2019, 03:19 PM   #161
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Test questions for our thread starter to calibrate what we are dealing with.

Earth shape. Flat, round or other?
Is space real?
When we see the ISS passing overhead, what are we seeing?
Why are all developed countries lying about the reality of space flight?
Why are physicists and engineers lying about space flight?
If communication satellites are not real, what are all those satellite dishes pointed at?
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Old 17th April 2019, 03:50 PM   #162
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Originally Posted by sts60 View Post
Iím not quite sure I understand your perspective, but the visitor center is north of the pad.
Wherever the NASA feed was taken.
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Old 17th April 2019, 03:59 PM   #163
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Originally Posted by Gingervytes View Post
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?
Because the scale isn't a rocket engine.
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Old 17th April 2019, 04:01 PM   #164
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Originally Posted by Trebuchet View Post
Here, just for grins, is a seriously similar thread at Cosmoquest, where we miss Jay Utah.
Does anyone still use Cosmoquest?
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Old 17th April 2019, 04:05 PM   #165
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Originally Posted by Captain_Swoop View Post
Does anyone still use Cosmoquest?
Yes, although not too much CT's there.
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Old 17th April 2019, 04:13 PM   #166
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Originally Posted by Doubt View Post
Test questions for our thread starter to calibrate what we are dealing with.

Earth shape. Flat, round or other?
Is space real?
When we see the ISS passing overhead, what are we seeing?
Why are all developed countries lying about the reality of space flight?
Why are physicists and engineers lying about space flight?
If communication satellites are not real, what are all those satellite dishes pointed at?
I think we can really streamline the calibration process. Just one question:

"If you say so, buddy; now what?"
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Old 17th April 2019, 04:16 PM   #167
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Originally Posted by bknight View Post
Yes, although not too much CT's there.
The way I figure Cosmoquest, their strategy is very different. Their goal is ghettoize and get rid of any against-the-mainstream claims that might otherwise derail their focus on fact based discussion.
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Old 17th April 2019, 04:19 PM   #168
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I know I was a mod there for many years.
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Old 17th April 2019, 04:32 PM   #169
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I wish you'd come back, at least to the modeling thread.
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Old 17th April 2019, 05:08 PM   #170
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Originally Posted by JoeMorgue View Post
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.
Are you sure it's not just a passive-aggressive Noah Fence drive-by?




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Old 17th April 2019, 05:39 PM   #171
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Kittens. Thread needs kittens. And recipes. Kitten recipes.
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Old 17th April 2019, 06:06 PM   #172
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rocket cannot propel in the vacuum of space

Originally Posted by MRC_Hans View Post
Yes. Pressure. The pressure accelerates the gas out. Where is the other side of that pressure?

Hans
F=m*a
The accelerated gas exerts a force equal and opposite to the force accelerating it. The base of rocket science :-).

Last edited by curious cat; 17th April 2019 at 06:24 PM.
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Old 17th April 2019, 06:20 PM   #173
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My wife and I often help groups of kids, sometimes as young as first graders, build and launch model rockets. During the build sessions, we describe some of the fundamentals of how rockets work. Most of the kids seem to understand. Not sure why it would be so challenging to an adult.
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Old 17th April 2019, 06:44 PM   #174
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Originally Posted by Gingervytes View Post
They ASSUMED incorrectly (on purpose), that there is an equal and opposite force from gas movement due to pressure gradient force. Escaping gas needs something to push off of



Mathematical proof that the thrust equation is false

Attachment 39978
Too bad this failed to make it to a reality based sub-forum.

No need to post a fake proof, the title is proof the OP is BUNK.
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Old 17th April 2019, 06:59 PM   #175
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Originally Posted by Norman Alexander View Post
Kittens. Thread needs kittens. And recipes. Kitten recipes.
Rocket propelled kitten, perhaps?
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Old 17th April 2019, 07:05 PM   #176
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Originally Posted by Horatius View Post
Well of course they didn't! Everyone knows rockets can't work in a vacuum!
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Old 17th April 2019, 07:15 PM   #177
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Originally Posted by Gingervytes View Post
You canít prove anything

All you can pick at is that I used nasa. Well I got the equation from NASAís website
There's your problem right there. NASA cannot have a 'website' because there is no 'web'. The 'internet' idea did not work. In 1969, DARPA sent an L and an O and the connection crashed. They were never able make the connection again due to entropy. The computer people had completely disregarded the T deltaS term in their programming. All their messages were lost, broken into pieces as they left their computers. They later claimed that these pieces were in fact 'packets', but few believed such an obvious coverup. In 1991 European scientists were assigned the job of creating an improved cover and came up with this 'web' idea, which they implemented by sending out operatives to load fake graphics (95% of which was porn, by the way) onto personal computers around the world. So I would not believe anything you get from this 'website' you talk of.
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Old 17th April 2019, 07:37 PM   #178
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Originally Posted by Norman Alexander View Post
Kitten recipes.


Ingredients

1 Mama Cat
1 or more Daddy(ies) Cat(s)
1 Barry White Album
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Old 17th April 2019, 08:27 PM   #179
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Originally Posted by sts60 View Post
The problem is that these people invariably have no idea at all what they’re talking about, which is always entertaining when they start trying to explain this claim to people who do this for a living (like some of us in this thread).
And these people are smart enough to know the difference between real science and a hoax, so the conclusion is obvious - they're in on it!

But how could NASA have managed to keep this hoax a secret for all these years? Surely someone would have figured it out by now? Well now someone has (or is about to) so we might as well come clean and tell the truth. You see, Gingervytes, the reason NASA has no trouble with people finding out about their hoax is that we are all in on it - every single person in the Universe - except you.

But that's not all.

Your mathematical proof that the thrust equation is false is entirely correct - in the real World. But you are not in the real World. You are actually in The Matrix, and the rest of us are computer simulations created by thought-capable machines to control you while using your body as an energy source. Actually I lie. You don't have a whole body anymore, you're just a brain in a jar.

Don't believe it? OK you got me. The Real Truth this time - you are actually just a computer simulation that we created to test the Matrix's defenses against trolls spouting nonsense (seems to be holding up OK so far...).

Or... perhaps you are not a computer simulation inside The Matrix, NASA isn't covering up a vast conspiracy, and rockets do work in space. Which scenario do you think is more likely?
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Old 17th April 2019, 08:35 PM   #180
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Originally Posted by Roger Ramjets View Post
And these people are smart enough to know the difference between real science and a hoax, so the conclusion is obvious - they're in on it!

But how could NASA have managed to keep this hoax a secret for all these years? Surely someone would have figured it out by now? Well now someone has (or is about to) so we might as well come clean and tell the truth. You see, Gingervytes, the reason NASA has no trouble with people finding out about their hoax is that we are all in on it - every single person in the Universe - except you.

But that's not all.

Your mathematical proof that the thrust equation is false is entirely correct - in the real World. But you are not in the real World. You are actually in The Matrix, and the rest of us are computer simulations created by thought-capable machines to control you while using your body as an energy source. Actually I lie. You don't have a whole body anymore, you're just a brain in a jar.

Don't believe it? OK you got me. The Real Truth this time - you are actually just a computer simulation that we created to test the Matrix's defenses against trolls spouting nonsense (seems to be holding up OK so far...).

Or... perhaps you are not a computer simulation inside The Matrix, NASA isn't covering up a vast conspiracy, and rockets do work in space. Which scenario do you think is more likely?
Surely, the answer to this must come down one, and only one thing.....did you swallow the red pill or the blue pill?
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Old 18th April 2019, 02:23 AM   #181
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Originally Posted by smartcooky View Post
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
On ignition, the rocket blew off a solid chunk of itself off. Pressure built up between the chunk and rocket. Like firing a gun, yes there is recoil because pressure builds up between the gun and bullet. The pressure pushes the bullet out and in turn pushes the gun. A rocket is like a gun firing a blank. The powder burns and moves out of the barrel only pushing off the air (assuming the gun powder was not encased in anything). Furthermore, the chamber fills up with smoke quickly and thus releasing any vacuum
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Old 18th April 2019, 02:27 AM   #182
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https://www.youtube.com/watch?v=AubIFUsq7Ss

Last edited by Gingervytes; 18th April 2019 at 02:29 AM.
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Old 18th April 2019, 02:54 AM   #183
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Originally Posted by Gingervytes View Post
On ignition, the rocket blew off a solid chunk of itself off. Pressure built up between the chunk and rocket. Like firing a gun, yes there is recoil because pressure builds up between the gun and bullet. The pressure pushes the bullet out and in turn pushes the gun.

What prevents the rocket exhaust, whatever phase it is in, from pushing the rocket in exactly the same way as the bullet pushes the gun?
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Old 18th April 2019, 03:25 AM   #184
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Originally Posted by Mojo View Post
What prevents the rocket exhaust, whatever phase it is in, from pushing the rocket in exactly the same way as the bullet pushes the gun?
A rocket has no bullet to push off of. Rockets do not expel solid chunks. Solids do not move like fluids. Pressure gradient force moves the gas and the gas pushes the bullet. The gas is bounces off the bullet and pushes the gun.
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Old 18th April 2019, 03:44 AM   #185
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Originally Posted by Gingervytes View Post
A rocket has no bullet to push off of. Rockets do not expel solid chunks. Solids do not move like fluids. Pressure gradient force moves the gas and the gas pushes the bullet. The gas is bounces off the bullet and pushes the gun.
Remove the bullet from the cartridge... be careful!

https://www.youtube.com/watch?v=PQ25g0Whgt0

Slip the cartridge into the chamber, point the gun in a safe direction and fire the weapon.

When you've done that, report back what you felt.
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Old 18th April 2019, 03:46 AM   #186
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Originally Posted by Gingervytes View Post
A rocket has no bullet to push off of. Rockets do not expel solid chunks. Solids do not move like fluids. Pressure gradient force moves the gas and the gas pushes the bullet. The gas is bounces off the bullet and pushes the gun.
Why do you think all the worlds physicists, engineers, rocket scientists, aerospace industries, space agencies, universities and scientific institutions would disagree with you?
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Old 18th April 2019, 03:53 AM   #187
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rocket cannot propel in the vacuum of space

Originally Posted by smartcooky View Post
Remove the bullet from the cartridge, slip the cartridge into the chamber, point the gun in a safe direction and fire the weapon.

When you've done that, report back what you felt.
Let me jump the gun :-). I am sure, he will report feeling a recoil, but it happened only because the propellant pushed against the surrounding air. IF it was in vacuum, there would be no recoil :-). He, of course, can't prove it, because he doesn't have a vacuum chamber.
Taking bets?
Anyway, I consider highly irresponsible giving somebody with Gingervytes' technical expertise any ideas about playing with guns and ammunition.

Last edited by curious cat; 18th April 2019 at 03:58 AM.
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Old 18th April 2019, 03:54 AM   #188
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Originally Posted by Gingervytes View Post
On ignition, the rocket blew off a solid chunk of itself off. Pressure built up between the chunk and rocket. Like firing a gun, yes there is recoil because pressure builds up between the gun and bullet. The pressure pushes the bullet out and in turn pushes the gun. A rocket is like a gun firing a blank. The powder burns and moves out of the barrel only pushing off the air (assuming the gun powder was not encased in anything). Furthermore, the chamber fills up with smoke quickly and thus releasing any vacuum
Rubbish! The thrust builds slowly while there is little if any smoke in the vacuum.

The check is to open the vacuum chamber to air and see if there is a change in thrust. There won't be any significant change.


You're just handwaving way the inconvenient evidence
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Old 18th April 2019, 03:57 AM   #189
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Originally Posted by curious cat View Post
Let me jump the gun :-). I am sure, he will report feeling a recoil, but it happened only because the propellant pushed against the surrounding air. IF it was in vacuum, there would be no recoil :-). He, of course, can't prove it, because he doesn't have a vacuum chamber.
Taking bets?
There are two things that I will never bet against...

1. Certainty
2. Stupidity


I've always wondered why, if rockets don't work in a vacuum, aerospace companies like SpaceX make specially modified versions of their rocket engines with a larger exhaust section and a significantly larger expansion nozzle to maximize the engine's efficiency in the vacuum of space.



Left to right:
Falcon 1 Merlin 1C, Falcon 9 Merlin 1C and Falcon 9 M-Vac 1C without extension nozzle - and this is the extension nozzle
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Old 18th April 2019, 03:58 AM   #190
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Originally Posted by curious cat View Post
Let me jump the gun :-). I am sure, he will report feeling a recoil, but it happened only because the propellant pushed against the surrounding air. IF it was in vacuum, there would be no recoil :-). He, of course, can't prove it, because he doesn't have a vacuum chamber.
If, of course, he did have a vacuum chamber, then he'd claim that the initial expulsion of gas fills the chamber leaving some gas present in it for the remaining gas to push against. This is not an educational issue, it's either a matter of irrational belief or of deliberate contrarianism for the purpose of attention seeking.

Originally Posted by curious cat View Post
Taking bets?
When the outcome is predetermined, that's always a bad idea for one of the parties involved.

Dave
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Old 18th April 2019, 04:17 AM   #191
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What do you mean by solid chunks?
Why does it matter if it is solid or if it is in a chunk?
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Old 18th April 2019, 04:23 AM   #192
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Originally Posted by smartcooky View Post
Surely, the answer to this must come down one, and only one thing.....did you swallow the red pill or the blue pill?
He made a mistake and took the white pill, the one that creates a vacuum between the ears.
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Old 18th April 2019, 05:08 AM   #193
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Originally Posted by Horatius View Post
Ingredients

1 Mama Cat
1 or more Daddy(ies) Cat(s)
1 Barry White Album
you forgot the bottle of catnip infused wine.
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Old 18th April 2019, 05:25 AM   #194
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Gingervytes, I took another look at your derivation. Your math isn't necessarily wrong (though that Ve=V is dangerous because it's not necessarily true anywhere but the exit point), but your interpretation is confused. While Ve is no longer explicit in the final formulation, it's still implied.

Try this: Make a little diagram with a pipe diameter and a fluid density and a Ve and calculate the force. Now, change just Ve and calculate the force again. It'll be different, because when you change Ve, Mdot will change too. So Ve still matters, it's just not explicit.
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Old 18th April 2019, 05:39 AM   #195
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Originally Posted by Gingervytes View Post
Stopped watching when three incorrect statements had been claimed. That was before the two minute mark.

1) Flow under pressure. The pressure is against something. That is your equal and opposite force (and what propels a rocket, in air as well as in vacuum).

2) An object falling under gravity. Silly claim that the opposite force should be against whatever dropped the object. Of course it is not. The force of gravity works between two masses. In the case in question, it is the falling object and Earth. Earth pulls down on the object and the object pulls up on the Earth (but as the Earth is a zillion times more massive that the object, the object moves while Earth stays virtually unperturbed).

3) Buoyancy. The pressure is between different parts of the fluid. As the floating object is less dense than the fluid, the downwards pressure it exerts is less than the upwards pressure the fluid exerts on it. Displacement of masses happen within the fluid.

#2 and #3 are totally irrelevant for the discussion of rockets.

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Old 18th April 2019, 05:47 AM   #196
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Originally Posted by Gingervytes View Post
A rocket has no bullet to push off of. Rockets do not expel solid chunks. Solids do not move like fluids. Pressure gradient force moves the gas and the gas pushes the bullet. The gas is bounces off the bullet and pushes the gun.
Pressure gradient is your keyword. The gas is under pressure in the combustion chamber. As it exits the nozzle it is accelerated because the outside pressure is low, or zero. The push on the rocket comes from accelerating the gas.

You might intuitively think that a solid (and hence dense) object like a bullet being accelerated would cause more push, but you would be mistaken: The burning fuel releases a given amount of energy, which is directed towards the nozzle/barrel. The density of the mass accelerated will determine the velocity it attains, but the energy will be the same. And hence the opposite energy accelerating the rocket will also be the same.

Hans
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Old 18th April 2019, 05:51 AM   #197
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Originally Posted by Gingervytes View Post
A rocket has no bullet to push off of. Rockets do not expel solid chunks. Solids do not move like fluids. Pressure gradient force moves the gas and the gas pushes the bullet. The gas is bounces off the bullet and pushes the gun.

Are you claiming that the exhaust from the rocket has no mass?
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Old 18th April 2019, 05:52 AM   #198
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Originally Posted by Gingervytes View Post
Solids do not move like fluids.
But many of the demonstrations of Newton's third law on Earth involve moving solids, not gases.

Regardless, gas has mass. Therefore moving gas must have momentum. That momentum is calculable. It is a firm fact of physics that momentum must be conserved. Amid all your attempts to muddy the waters with irrelevant analogies and demonstrations, you have omitted to explain why you believe this fact doesn't hold for rockets. If Newtonian physics is universal, then rockets must work the way we say.
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Old 18th April 2019, 05:58 AM   #199
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Oh, I see I already explained how a rocket basically works. Not that I have much hope of this turning into a rational discussion, but .... I repost the explanation here for you ro re-read:

Originally Posted by MRC_Hans View Post
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.)

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Old 18th April 2019, 05:59 AM   #200
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I am tickled pink I knew the science on this stuff already. I feel almost adult! Almost.

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Jay,

The nozzle part is new to me. As I've always been fascinated by steam engines (the history of changes in stream locomotives is like an object lesson in structured creativity), I was wondering if you know of any other tidbits of still-valid inventions relating to steam? (Apart from it's larger role in deriving the 2nd Law of Thermo.)

Thks.

ETA: I guess that may be a derail, though. Shucks. For another rainy day, then.
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