People on skateboards.

Why an infinite reaction mass?

Quote from: rabinoz on December 12, 2015, 01:05:12 AM

At what ambient pressure does a rocket fail to work?[/b]

LULZ!!!

Obvious lurker/stalker is obvious...
Well, I guess that'd depend on the nozzle design, wouldn't it, .?
But unless NASA can design a nozzle that is Infinitely wide, or provide an Infinite amount of 'reaction mass' (lol!), then their shpayze-rokkits won't be working too well.
*Yawn!*

You say "Well, I guess that'd depend on the nozzle design, wouldn't it"  Well, no it does NOT!
You still cannot answer a simple question.  A rocket nozzle does not need to be "optimum" to work at low pressures.  The equation I gave you showed that the static thrust increases as the pressure decreases!  The rocket obviously does work at normal air pressure, so at what air pressure does it stop working?  Simple question, simple answer.

BTW when you design your next rocket nozzle don't try to make it "optimum" for a very low pressure.  It might theoretically give the best "specific impulse" for the fuel, but the nozzle will be excessively large and heavy!  It is "optimum" in that one respect only, but not the best design.  On second thoughts, papa, please do not design a rocket nozzle!

You seem to have NASA on the brain.   Konstantin Tsiolkovsky knew that rockets did not depend on air pressure, and he died 23 years before NASA.  NASA did not invent rockets, much of the work was done well before they came around!

 Why would looking at YouTube and replying make me a "lurky/stalky youtube troller Rab Downunder." any more than you are?
I see where you get you funny ideas from.  EU school kids handouts and Popular Mechanix seem to be your standard and I thought you FEers went on and on about the false indoctrination schoolkids get!

I thought you FEers went on and on about the false indoctrination schoolkids get!

Instant Fail from the man voted 'most blocked youtube troll 2015', our very own 'rabinoz', aka 'rab downunder'.

Because I'm not a flat earther.

Nor am I a raown derfer.

I have stated this repeatedly, so why should I answer your troll-spam questions when you clearly have not even read my posts?

It does not matter what shape the earth is; a rocket still cannot function in a vacuum.

Now; Carry On Wasting your Weekends by Lying on the Internet!

Cos that doesn't look at all suspicious...

Lol yes it does!

Toodle-pip, Losers...

Where does popular mechanics say a rocket pushed off the atmosphere?

Where does popular mechanics say a rocket pushed off the atmosphere?

So are you agreeing that jet engines DO push off the atmosphere, but still saying rocket engines DON'T?

You raown derf trolls really do need to make your minds up about exactly what does what & how...

Wouldn't want anyone to think you're just making shit up as you go, would you?

Lol yes you are & everyone knows it anyway!

Once again: Carry On Lying!

Quote from: sokarul on December 12, 2015, 05:56:27 AM

Where does popular mechanics say a rocket pushed off the atmosphere?

So are you agreeing that jet engines DO push off the atmosphere, but still saying rocket engines DON'T?

You raown derf trolls really do need to make your minds up about exactly what does what & how...

Wouldn't want anyone to think you're just making shit up as you go, would you?

Lol yes you are & everyone knows it anyway!

Once again: Carry On Lying!

No, I'm not saying that. Just like you aren't saying rocket engine are attached to commercial aircraft. Don't jump to stupid conclusions.
So I ask again where does the article claim that a rocket or jet engine pushes off the atmosphere?

As for convergent/divergent nozzles; fortunately for us, genuine engineers have to use them, for turbines etc, so the facts of their operation cannot be twisted & obscured by NASA pseudo-science.

And one of the facts of their operation is that they require back-pressure in order to work, a thing that cannot be achieved in an infinite vacuum.

Please cite a credible source that says Del Laval nozzles can't work if back-pressure is zero.

Quote from: markjo on December 11, 2015, 04:49:53 PM

Quote from: Papa Legba on December 11, 2015, 09:40:41 AM

No matter how hard you try to spin it, cultists, every child knows that You cannot Push on Nothing.

No one is saying that you can.

LOL!!!

Actually you all are; hence your insane claims that the rocket's own fuel mass is somehow Object B, and a rocket somehow 'pushes on itself' (lol!).

If the mass of the rocket is object A and the mass of the fuel is object B, then the rocket isn't pushing on itself (object A), is it?

Quote from: markjo on December 11, 2015, 04:49:53 PM

I suggest that you take your own advice and study up on Mass Flow as it applies to Fluid Dynamics.

If the Recoil Principle alone were the explanation for how rockets function, then the reaction mass needed for a rocket to travel any distance would approach Infinite...

Yes, that's sorta true.  That's why 2/3 of the total mass of the Saturn V was the mass of the fuel and oxidizer for the first stage which only got about 67 km high before burnout.

Which doesn't seem very practical, does it?

That depends,  If you want to go to the corner market, then no, it isn't very practical.  But if you want to go to space, then there really aren't any more practical alternatives,

Are we done here?

I don't know.  Do you finally admit that a rocket can carry its own reaction mass?

Good; then Carry On Lying!

Keep on shitspamming.

Fantastic stuff!

You should write a sci-fi novel based on this bullshit...

Oh, wait, you already did - it was called 'teh munn lanndinks'.

Toodle-pip, Losers!

And you little kids say I shitpost.

We do.

And we are Correct.

Fantastic stuff!

You should write a sci-fi novel based on this bullshit...

Oh, wait, you already did - it was called 'teh munn lanndinks'.

Toodle-pip, Losers!

This would make a very boring book, though.

We do.

And we are Correct.

He destroyed you. Why can you never make a proper rebuttal?

Oh I know, don't have one.


Lol

Fantastic stuff!

You should write a sci-fi novel based on this bullshit...

Oh, wait, you already did - it was called 'teh munn lanndinks'.

Toodle-pip, Losers!

If you can't refute it, then dismiss it. 

Sounds like an admission of defeat to me.

This would make a very boring book, though.

It was indeed a very boring book...

For educated adults.

For kids & retards it was a soopah-speshul shapyze-expluraryshun adventcha & all-round BIIIIIIG HOOPLAH though...

There's a sucker born every minute, is there not, Mr. only-four-posts-but-definitely-not-a-sock noob?

Oh, & sokarul; in case you haven't noticed - everyone is laughing at you.

No, really; they are!

Toodle-pip, sci-fi fans & Losers; see you at Comicon!

Oh, & markjo; stop hiding behind the curtain, Captain Coward.

We all know you have access to the site's architecture, as well as 1000's of sock-puppets.

Just stop the bullshit, okay?

It's getting boring.

Sokarul, have you ever been to a farm?

Hmm...

Maybe you ain't just the average markjo back-up sock, nodnyl.

We'll see...

But even if you ain't, don't expect owt from sokarul; he's the shitpost Terminator.

He is.

Sokarul, have you ever been to a farm?

Yes

And you little kids say I shitpost.

He is.

Quote from: rabinoz on December 12, 2015, 03:41:23 AM

I thought you FEers went on and on about the false indoctrination schoolkids get!

Instant Fail from the man voted 'most blocked youtube troll 2015', our very own 'rabinoz', aka 'rab downunder'.
Because I'm not a flat earther.  Nor am I a raown derfer.
I have stated this repeatedly, so why should I answer your troll-spam questions when you clearly have not even read my posts?
It does not matter what shape the earth is; a rocket still cannot function in a vacuum.
Now; Carry On Wasting your Weekends by Lying on the Internet!
Cos that doesn't look at all suspicious...
Lol yes it does!  Toodle-pip, Losers...

Yes, I read your posts, they just say a rocket cannot function in a vacuum, and give no sound reasons - look up "choked flow"!
No, I would no accuse the EU or Popular Mechanics (BTW what issue?) or lying!  This stuff is written by journalists!  I guess you have seen how they can mangle things - with the best of intentions.
You claim "Instant Fail from the man voted 'most blocked youtube troll 2015'".  But,
1) Probably correct since the number of voters is only ONE, dear papa!
2) I have not yet been blocked on Youtube (that I know or care about).

Just what sort of response to you expect to get with your OP:
"Here is a thread for satanic sci-fi cultists to post photos/videos of people on skateboards that they think somehow prove that rockets will function in a vacuum.
Newton, Joules & Thomson will be spinning in their graves at such nonsense, but I guess these cultists are too satanically brainwashed to comprehend how basic scientific principles work...
Whatever; knock yourselves out, psychos!"
So "Because I'm not a flat earther. Nor am I a raown derfer.", what does that leave, maybe its a dodecahedron? - each face is a pentagon, should be significant!

New definitions: Liar - anyone disagreeing with Papa!  satanic sci-fi cultists - anyone disagreeing with Papa!
But you still have NEVER answered the basic question! 
To put into perspective:
"On July 17, 1962, American test pilot Robert White took the X-15 to an altitude of 314,688 feet. But it’s Russian pilot Alexandr Fedotov who holds the world altitude record, set on August 31, 1977, when his MiG E-266M reached a mere 123,523 feet." from http://www.airspacemag.com/need-to-know/who-holds-the-altitude-record-for-an-airplane-141522931/?no-ist
The SR-71A "Blackbird" had a service ceiling of "over" 85,000 ft, so its jet engines work there.

Altitude	Pressure
0 ft	1013.25 mbar
85,000 ft	25.05 mbar	SR-71A service ceiling
123,523 ft	4.68 mbar	MiG E-266M record jet plane
314,000 ft	0.00117 mbar	X-15 record winged rocket plane

So at which altitude does the rocket stop working - some magic going on! 
BTW I am NOT asking about a REAL vacuum, just extremely low air pressure!  So get your log rules or slide tables out and work it out.

Do you have a point?

Except for pompously replying to your own pompous posts, throwing a dozen half-baked ideas round in the hope readers don't notice they're all blather, grovelling to the mods & generally showing us all how you gained your coveted 'most blocked youtube troll' title, that is?

Anyhoo, at least when you say this:

So at which altitude does the rocket stop working

You are acknowledging that they DO stop working when atmospheric pressure is low enough...

That's a start!

But when you say this:

look up "choked flow"!

I am most disappointed, as we have already established that 'choked flow', or convergent/divergent, nozzles, require back-pressure in order to function.

And you cannot achieve back-pressure in a vacuum.

Toodle-pip, strange Australian...

Still haven't learned that a vacuum isn't a force.
If you flow more in than out, what do you get?

If you flow more in than out, what do you get?

Teh lulz!

He is.

Once again can't make a proper rebuttal.

Maybe he gave good advice.

Maybe you're trying to lick his arse so that he locks yet another thread full of evidence of space-fraud?

You know; like this:

The combustion chamber of a rocket is open to the near-infinite vacuum of space.

Therefore, no gas can even be meaningfully said to exist within it, let alone combust.

Any gas introduced therein when the pressurised fuel tank leading to the combustion chamber is opened will simply expand freely into the enormous, zero-pressure vacuum, following the path of least resistance & doing no work whatsoever.

This will continue for as long as the fuel tank & chamber are open to the vacuum, until both exterior & interior pressures are equalised at zero.

It is a beautifully simple concept, fully supported by All the laws of physics, yet you 'round earthers' (lol!) just can't seem to grasp it...


Plus this:

You all claim that the recoil of a gun is a valid analogy for how a rocket works in a vacuum.

Here is why it is not:

With a gun you have object A, the mass of the gun; the expanding propellant, P, the gunpowder, sited between them; and object B, the mass of the bullet.

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No object B, see?

Thus, you have removed the necessary recoil mass required to produce motion.

But we know a rocket DOES produce motion, don't we?

Ergo, some other mass MUST be taking the place of object B.

& the ONLY possibility for that other mass is the Atmosphere.

Ergo, NO atmosphere, NO motion; rockets CANNOT function in a vacuum.

Q.E.D.

No matter how hard you try to spin it, cultists, every child knows that You cannot Push on Nothing.

No maths required; only common sense.


Then there's the fact that you are all trying desperately to confine this 'debate' to the wrong branch of physics, i.e. Solid Mechanics rather than Fluid Mechanics...

Kinda dishonest of you, dontcha think?

Pressure-Gradient Forces, Gas Laws, Fluid Mechanics, Continuum Assumption & Joules Expansion are the areas I suggest neutral readers research.


Read & Learn!

Oh, look Papa's the only one in step!

This stuff is written by journalists!

What makes you think this was written by journalists?





And what makes you think this journalist was lying?




*Yawn!*

Then there's the fact that you are all trying desperately to confine this 'debate' to the wrong branch of physics, i.e. Solid Mechanics rather than Fluid Mechanics...

Then why do you keep bringing up free expansion which is part of thermodynamics?

Cool. Then let people research that, too...

Cos wherever they look, they'll find no genuine physics that supports the idea of a gas-powered rocket providing thrust in a vacuum.

They'll find plenty of pseudo-science & pseudo-scientific gatekeepers though...

Won't they, Mr. 'content nazi'?

Object B is the fuel.

Incorrect.

He is.