The Benouilli Effect

  • Thread starter lavalamp
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  • #26
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Originally posted by Fairfield
I won't venture to offer my interpretation of what I observed there, when I made a fat wing with a large camber, because I am the low man on the totem pole for physics education here. But I hope nobody missed it.
You are probably not the low man.
My sophomore year in high school I had to take a general Science class. That's the only formal Physics education I've had. The rest is picked up from reading, and is spotty.

That being the case, what did you observe? (I can't do that site with this webtv).

-Zooby
 
  • #27
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Originally posted by lavalamp
You can't measure the velocity of every particle, but it can be shown that the r.m.s. speed of particles in the air is directly related to the speed of sound (ie: they are the same).
OK, I hope you can see that you started off explaining everything in reverse.
And from the temperature of the air and the mass of the particles in the air, the r.m.s. speed can be calculated for each type of particle.
So, what this is telling me is thatyou actually have to start with the temperature and mass, then you can find the r.m.s.

The explanation of negative velocities made sence.

So your ultimate point is that finding the r.m.s. speed for air of a given mass at a gven temperature will automatically give you the speed of sound in air at that mass and temperature?
 
  • #28
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Zooby:

Regarding my take on the Foil Sim picture at the NASA web site,
since a picture is worth a thousand words, I don't think I can fill that request in any useful way. If you have MS WORD, in practically any version, I could probably send you a still picture made with the Print-Screen key, by e-mail, as an attachment. But if you haven't seen the picture in motion first, it'll be hard to make any particular sense of it.

I'm very curious about why webtv can't deal with the Foil Sim program. Surely the link is not all that much different than the link to Science Forums. What's the obstacle?
 
  • #29
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I will confess that the primary obstacle is my laziness when confronted by the complicated instructions on how to operate the simulation. When I saw the word "java" that killed my interest completely because the webtv won't do java.

My impression is that the fatter the aerofoil the slower the speed must be for it to work at all.

Edit: OK, I went back to the sight and tried everything I could but the animation wont work for webtv. Oh, well.
 
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  • #30
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Zooby:

If the Foil Sim program won't work for you on the net, maybe it will work for you if you download it. That option is available there.

But let me double check whether you tried these particular things.

1. Were the dashes moving when the picture arrived?

2. Could you stop the dashes from moving if you clicked on the word "Frozen" which is just below the dashes?

3. If you click on the blue button labeled, "Shape/Angle", did it change the array of boxes, over about 3" to the right, to a different set of boxes?

4. Can you get any reaction in the main picture when you click in any of those new boxes on the right?

If nothing happened in these tests, then I guess you are truly blocked from operating the program on the net.
 
  • #31
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Thanks for the suggestions, Fairfield. The dashes were not moving, and nothing I did would make them start. WebTv can download nothing. It's just a modem and a keyboard. Not even a mouse - you have to use the arrows. (I can plug a printer in, which I have done, because these just print straight off the web.)

-Zooby
 
  • #32
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Try a little common sense, Fairfield: A symmetric airfoil's upper and lower surfaces are the same, yet the plane flies ... Ever hear of a little something called 'angle of attack'?
 
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  • #33
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Originally posted by Chagur
Try a little common sense, Fairfield: A symmetric airfoil's upper and lower surfaces are the same, yet the plane flies ... Ever hear of a little something called 'angle of attack'?
Did I say something to the contrary somewhere? Please quote me.
 
  • #34
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Originally posted by Chagur
Try a little common sense, Fairfield: A symmetric airfoil's upper and lower surfaces are the same, yet the plane flies ... Ever hear of a little something called 'angle of attack'?
Fairfield did not describe what he saw, so what fuels this testy attitude and irritation? You can read minds?
 
  • #35
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This was your quibble:

Originally posted by zoobyshoe
OK, this part here is confusing to me because I don't see how they can possibly measure the velocity of any individual particle, much less all of them.
I was simply trying to explain how you could attain a value for the r.m.s. speed, since as you said, it is not possible to measure the velocity of each individual particle.
 
  • #36
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Yes, Fairfield, you did:
The importance of the "lift" airfoil design is over hyped
because most airplanes can be flown upside down
without losing altitude, it just takes more gas.
Completely ignoring that when flying 'upside down' you
are relying completely on an increased angle of attack
and that the required AofA increases drag; hence the
greater power/fuel requirement.

No, zoobyshoe, I cannot read minds, but I do know a little
about aerodynamics. A simple vector force analysis is all is
all that is required to determine even extremely slow flight
or 'flight' via turbulence creation, the 'flapping of wings',
either by birds or insects.

Given the required control surfaces and sufficient power,
even a kitchen table can be made to 'fly'. An excellent
example would be 'the hopeless diamond' which became
the F-117 in its combat configuration.
 
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  • #37
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OK Chagur, I over simplified the problem. I completely agree with you.
 
  • #38
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Originally posted by Chagur

No, zoobyshoe, I cannot read minds...
That's good, cause neither can anyone else here. Therefore quote the remark you are taking exception to, especially when you are being irritated and testy about it, because otherwise it looks like you are refering to the last thing said.
 
  • #39
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Originally posted by Chagur A simple vector force analysis is all is
all that is required to determine even extremely slow flight
or 'flight' via turbulence creation, the 'flapping of wings',
either by birds or insects.

Given the required control surfaces and sufficient power,
even a kitchen table can be made to 'fly'. An excellent
example would be 'the hopeless diamond' which became
the F-117 in its combat configuration.
I am not sure why you are directing this explanation at me. I am the one who said earlier that it is possible to design a wing that works exclusively on Newton III.
 
  • #40
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Originally posted by zoobyshoe
Thanks for the suggestions, Fairfield. The dashes were not moving, and nothing I did would make them start. WebTv can download nothing. It's just a modem and a keyboard. Not even a mouse - you have to use the arrows. (I can plug a printer in, which I have done, because these just print straight off the web.)

-Zooby
Now that webtv has been exposed, may I suggest an economical computer with a Windows operating system, and all the needed extras, which can be had for about $440 (before tax and shipping) at

" http://www.tigerdirect.com/applications/Category/category_tlc.asp?CatId=6 "

If you love the frustration of installing the operating system yourself you can get a computer for about $300, and buy a slightly passe version of Windows at

http://www.recycledsoftware.com/

for about $100. The software sold there is not used, just superseded. Make sure you get an OEM version of Windows, and not earlier than Windows 95, if you buy it. You'll still need to get a monitor, or else an adapter card to use your TV as a monitor.
 
  • #41
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Not a bad suggestion at all, except my finances are such that the odd 4 or 5 hundred dollars that comes my way must always go to maintaining my vehicle, among other more pressing things.

The webtv is as limited as you can get and still be on the web, and I find I have to make excuses for it frequently, but it is cheap and, at this point, that overides the limitations.
 
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