Can Plane Take Off

Morphyous_foh

shitlord
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findar said:
i think the ice cube question is the new one.

an ice cube is in a glass of water. it melts.

will the water level raise, lower, stay the same?
The level stays the same for the most part.

If you froze a full glass of water, the ice is going to expand. If the entire thing was ice and it melted, it is going to reduce in volume relative to the original ice. So does this volume cause the ice in glass to go down? I would say not. To the human eye you are not going to see a large enough change in water level to see an increase/decrease.

The only way to see a huge increase or decrease is to make the glass of water so fucking narrow that a single drop of water added would raise the level of water.

To make the water level raise?

You can"t, even if you had the glass filled with 99% ice and 1% water, the thing isn"t going to go up in water level. Ice is not densely packed in and when it melts, it"s going to have less molecules of water than the same volume of ice, but with all liquid water.

To make the water go down?

The only real way to "see" a noticeable change in water level is the make the entire glass filled with ice (pretty much fill the glass with water, freeze it, then let it melt). Ice takes more volume than liquid water, so you will see the water level drop.
 

Abysmal_foh

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that was the stupidest fucking thing i have ever heard. the answer is on page 23. never post anything even vaguely related to science ever again.
 

brekk

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eureka!!!


nuff said.

(if you don"t get this you fail)
 

Cadrid_foh

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I guess the notion of slower moving (hence, more compact) molecules being the result of colder temperatures (i.e. less energy) and faster moving (hence, more wide-spread) molecules being the result of higher temperatures (i.e. more energy) was out of his grasp during chemistry/physics.

It"s this same principle that explains why one inch of snow equates to 10 inches of rainfall; less energy = more density = less space used; more energy = less density = greater space used.
 

Torrid_foh

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Nar said:
I"m not going to read through 22 pages of threads to see if someone beat me to the punch - but Mythbusters did this already.
I"m (very) far from an expert on aerodynamics, but I don"t think Mythbuster"s explanation and test was entirely accurate.

An air foil generates lift by slicing the air and creating two pressure zones. The air moving above the wing takes longer to traverse the width of the wing, creating a lower pressure zone. More pressure on the bottom of the wing will then push the wing up.

So, in order to slice through the air and generate lift under the wings, the air and/or the aircraft need to be moving relative to each other..

I think the reason why the planes on Mythbusters took off was because the propeller was moving the air over and under the wings. It also appeared to me that the planes were out-pacing the conveyor belts before they took off, although not by much. I doubt an aircraft powered by a gas turbine would take off nearly as easily, if at all, or at the very least would need significantly more power than what would be needed if it were not on a conveyor. Also the placement of the props/turbines would (I assume) greatly vary the results. I also noticed that the planes Mythbusters used had a seemingly high thrust to weight ratio. They also didn"t measure how much thrust was needed to take off.

So really, I think the answer is both, depending on the aircraft. If a plane had a means of propulsion that did not push air over the wings (such as a rocket perhaps?), or did not push air fast enough, then it would not take off on a conveyor. The exception to this being aircraft that have a thrust to weight ratio greater than one, and even then the thrust would have to be multi-vectorable. If a plane could always take off on a conveyor, then aircraft carriers would use conveyors.

I could be wrong though.
 
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Cadrid said:
I guess the notion of slower moving (hence, more compact) molecules being the result of colder temperatures (i.e. less energy) and faster moving (hence, more wide-spread) molecules being the result of higher temperatures (i.e. more energy) was out of his grasp during chemistry/physics.

It"s this same principle that explains why one inch of snow equates to 10 inches of rainfall; less energy = more density = less space used; more energy = less density = greater space used.
A key exception being of course water, which is really the only substance germane to the retarded question at hand.

Also, the movement of individual atoms and molecules in snow and rain for determining density is largely irrelevant. Water equivalence of snow is largely due to whichever crystal shape is most prevalent, which is determined by a lot of external factors.

Short/Common Sense answer: Snow on the ground has a lot of air in it.
 

Cad

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So Torrid thinks a prop plane can take off on a conveyor because it "pushes air over the wings, generating lift" but a ROCKET would be held at a standstill?

Wow.
 

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Torrid said:
If a plane could always take off on a conveyor, then aircraft carriers would use conveyors.
Im sure designing a conveyor belt able to operate in upwards speeds of 80 miles an hour, while carrying more that 10 tons in weight will not be is not an easy task.
 

Pancreas

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Cadrid said:
I guess the notion of slower moving (hence, more compact) molecules being the result of colder temperatures (i.e. less energy) and faster moving (hence, more wide-spread) molecules being the result of higher temperatures (i.e. more energy) was out of his grasp during chemistry/physics.

It"s this same principle that explains why one inch of snow equates to 10 inches of rainfall; less energy = more density = less space used; more energy = less density = greater space used.
Except liquid water takes up less space than frozen water. It"s the same principle that causes physics-ly challenged individuals to neglect winterizing their homes as they go on vacation for a month just to come home to a house full of burst pipes.

As far as the snowfall thing... why do you often hear about snow storms in excess of 3 to 6 feet of snow but no where on earth has 6 feet of rain fallen within the same time frame? Unless of course you count that guy who had the boat full of animals, but that"s hardly a scientific example.
 

Sylas

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I"m (very) far from an expert on aerodynamics, but I don"t think Mythbuster"s explanation and test was entirely accurate.

An air foil generates lift by slicing the air and creating two pressure zones. The air moving above the wing takes longer to traverse the width of the wing, creating a lower pressure zone. More pressure on the bottom of the wing will then push the wing up.

So, in order to slice through the air and generate lift under the wings, the air and/or the aircraft need to be moving relative to each other..

I think the reason why the planes on Mythbusters took off was because the propeller was moving the air over and under the wings. It also appeared to me that the planes were out-pacing the conveyor belts before they took off, although not by much. I doubt an aircraft powered by a gas turbine would take off nearly as easily, if at all, or at the very least would need significantly more power than what would be needed if it were not on a conveyor. Also the placement of the props/turbines would (I assume) greatly vary the results. I also noticed that the planes Mythbusters used had a seemingly high thrust to weight ratio. They also didn"t measure how much thrust was needed to take off.

So really, I think the answer is both, depending on the aircraft. If a plane had a means of propulsion that did not push air over the wings (such as a rocket perhaps?), or did not push air fast enough, then it would not take off on a conveyor. The exception to this being aircraft that have a thrust to weight ratio greater than one, and even then the thrust would have to be multi-vectorable. If a plane could always take off on a conveyor, then aircraft carriers would use conveyors.

I could be wrong though.
Wow. please tell me you"re trolling.

you missed 24 pages of everyone with any sense whatsoever explaining that the conveyor does absolutely nothing, and still managed to fuck it up so bad to insinuate that the conveyors magically extend the length of the runway somehow, so that it would be better to have aircraft carriers fitted with conveyor belts?
The length of the runway isn"t the problem so much only that it limits how much lift can be generated, which is sorta why they use slingshots instead.
 

Aulirophile_foh

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Torrid said:
If a plane could always take off on a conveyor, then aircraft carriers would use conveyors.
As opposed to the extremely efficient steam catapults they use now? The plan can take off, but it makes the wheels go twice as fast. That wears it out faster. Not to mention it could take a longer runway, which space is limited on a boat and all. You"re not understanding the question. The plane doesn"t stay in the same place just because the conveyer is matching speed. That"s the whole point, the plane STILL moves, despite the conveyer.
 

brekk

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Cadrid said:
It"s this same principle that explains why one inch of snow equates to 10 inches of rainfall;
less energy = more density = less space used;
more energy = less density = greater space used.
water is its densest(sp?) at 4 degrees C, any colder or warmer and it expands.

Torrid said:
I"m (very) far from an expert on aerodynamics
never woulda fucking guessed
 

Zuuljin_foh

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So what your saying is.... if all the iceburgs on earth melted due to global warming... the ocean levels would stay the same?! I knew waterworld was a myth! =P
 

Twobit_sl

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It"s not the ice in the ocean that is the problem, it"s the ice that is landlocked that finds it way to the ocean that would be the issue.
 

Torrid_foh

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Cad said:
So Torrid thinks a prop plane can take off on a conveyor because it "pushes air over the wings, generating lift" but a ROCKET would be held at a standstill?
Well, if the rocket thrust was aimed exactly parallel to the conveyor belt, yes.

Keeping in mind that this is a hypothetical scenario, and not considering things like the amount of friction holding down the plane on the conveyor.

Although this brings up a point I neglected to mention in my post, which was that the prop plane was pointed at an upward angle. I"m just saying that I don"t think that alone is the reason why it took off, and that many aircraft (especially jets) would be unable to take off that way.

Kazgrim said:
you missed 24 pages of everyone with any sense whatsoever explaining that the conveyor does absolutely nothing,
The conveyor doesn"t do nothing. It decreases the speed of the air relative to the plane.

Kazgrim said:
and still managed to fuck it up so bad to insinuate that the conveyors magically extend the length of the runway somehow, so that it would be better to have aircraft carriers fitted with conveyor belts?
No, I said the opposite. I said that IF conveyors always worked, then they would be used on aircraft carriers. If they worked, they would essentially give every plane vertical take off capability.

I"m just tossing ideas out here is all. I suppose I should have known better to reply to a 3 year old thread though.
 

findar_foh

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Torrid said:
Well, if the rocket thrust was aimed exactly parallel to the conveyor belt, yes.

Keeping in mind that this is a hypothetical scenario, and not considering things like the amount of friction holding down the plane on the conveyor.

Although this brings up a point I neglected to mention in my post, which was that the prop plane was pointed at an upward angle. I"m just saying that I don"t think that alone is the reason why it took off, and that many aircraft (especially jets) would be unable to take off that way.



The conveyor doesn"t do nothing. It decreases the speed of the air relative to the plane.



No, I said the opposite. I said that IF conveyors always worked, then they would be used on aircraft carriers. If they worked, they would essentially give every plane vertical take off capability.

I"m just tossing ideas out here is all. I suppose I should have known better to reply to a 3 year old thread though.
saving quote to prevent editing. ill let someone else rip you limb from limb though.