Bernoulli, yes or no?

Does Bernoulli’s law apply to an airfoil?

  • Yes

    Votes: 42 73.7%

  • No

    Votes: 5 8.8%

  • Maybe

    Votes: 2 3.5%

  • I don’t speak Italian but I like pizza

    Votes: 8 14.0%

  • Heretic!

    Votes: 0 0.0%
  • Total voters
    57
Clark1961

Clark1961

Touchdown! Greaser!
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We’ve all read about and looked at pictures depicting airflow around an airfoil. Of course lots of research has gone into determining the lift and drag of various shapes. Some researchers believe Bernoulli doesn’t really apply and that lift is a Newtonian thing.

The more I think about it the more I believe lift is Newtonian. After brain dumping on an FAA knowledge test yesterday I had a bit of epiphany on lift and why Bernoulli doesn’t apply. I do have a background in fluid flow so there is some bias. Also some solid understanding of the physics of fluid flow.

Anyway, thought this might be a good POA discussion/argument topic.
 
Gawd I love pizza. I'm Italian so I guess I have to side with Mr. Bernoulli. But actually it's both IMO.
 
I needed more choices.....was fighting the pizza response. o_O


sounds like someone needs to take a trip and spend more time in the wind tunnel. :D I'm sure you know that fluids become incompressible....and more Newtonian at higher Reynolds numbers. So....it depends.
 
At best, he applies a negligible amount of lift.
He gets far too much credit and he is riding Newton's coattails and taking almost all of the credit.

Really ****es me off.

Certainly, I can recreate the Mr. Wizards World episode where he blows under the folded piece of paper and it suctions to the desk versus flipping over but I think paper airplanes, kites, and symmetrical wings expose Bernoulli for what he really is. A crafty vacuum salesman.
 
Ryanb said:
NY Style.
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Sicilian, thick as hell! My grammom made it that way and she came from Italy. Of course she called it tomato pie and it only had sauce and a couple spices on it. Pizza is so American. But, I like that too. Damn I'm hungry...

How's that for thread drift? He did have pizza though as an answer...
 
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Checkout_my_Six said:
I needed more choices.....was fighting the pizza response. o_O


sounds like someone needs to take a trip and spend more time in the wind tunnel. :D I'm sure you know that fluids become incompressible....and more Newtonian at higher Reynolds numbers. So....it depends.
Click to expand...
Wind tunnels are part of the problem folks have with understanding lift. The only thing we know for certain about airfoils in wind tunnels is that all the observations apply directly in and only in wind tunnels.
 
mscard88 said:
Sicilian, thick as hell! My grammom made it that way and she came from Italy. Of course she called it tomato pie and it only had sauce and a couple spices on it. Pizza is so American.

How's that for thread drift? He did have pizza though as an answer...
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Sicilian is good, but NY Style has a higher stall speed being as thin as it is. Also more aerodynamic.

Hey, atleast I’m trying to keep this thread Aviation related!
 
Ryanb said:
Sicilian is good, but NY Style has a higher stall speed being as thin as it is. Also more aerodynamic.

Hey, atleast I’m trying to keep this thread Aviation related!
Click to expand...

Too thin. You probably like your womens thin too huh?

skinny-wrinkles-1.jpg
 
Ryanb said:
Sicilian is good, but NY Style has a higher stall speed being as thin as it is. Also more aerodynamic.

Hey, atleast I’m trying to keep this thread Aviation related!
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Do pepperoni slices add lift or drag?
 
Clark1961 said:
Do pepperoni slices add lift or drag?
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Pepperoni is fine, it’s sausage that you have to watch out for. Add’s drag and spoils the smooth airflow over the crust.
 
Ryanb said:
Pepperoni is fine, it’s sausage that you have to watch out for. Add’s drag and spoils the smooth airflow over the crust.
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Sausage is what’s for breakfast. It does not enter into the pizza equation.
 
Bernoulli's equation (the real equation - not the air buddies meeting at the trailing edge myth) can be easily derived from Newtons Equation with a few basic assumptions (ideal gas being the primary one), so there is really no difference and both can be used to model / calculate lift and both give exactly the same answers.
 
Capt. Geoffrey Thorpe said:
Bernoulli's equation (the real equation - not the air buddies meeting at the trailing edge myth) can be easily derived from Newtons Equation with a few basic assumptions (ideal gas being the primary one), so there is really no difference and both can be used to model / calculate lift and both give exactly the same answers.
Click to expand...


Oh along come facts and math...
This stuff really gets in the way of our conjecture.
 
Capt. Geoffrey Thorpe said:
Bernoulli's equation (the real equation - not the air buddies meeting at the trailing edge myth) can be easily derived from Newtons Equation with a few basic assumptions (ideal gas being the primary one), so there is really no difference and both can be used to model / calculate lift and both give exactly the same answers.
Click to expand...
Explain how the air buddies meeting at the trailing edge is a myth
 
Clark1961 said:
We’ve all read about and looked at pictures depicting airflow around an airfoil. Of course lots of research has gone into determining the lift and drag of various shapes. Some researchers believe Bernoulli doesn’t really apply and that lift is a Newtonian thing.

The more I think about it the more I believe lift is Newtonian. After brain dumping on an FAA knowledge test yesterday I had a bit of epiphany on lift and why Bernoulli doesn’t apply. I do have a background in fluid flow so there is some bias. Also some solid understanding of the physics of fluid flow.

Anyway, thought this might be a good POA discussion/argument topic.
Click to expand...
Which FAA exam?
 
Capt. Geoffrey Thorpe said:
Bernoulli's equation (the real equation - not the air buddies meeting at the trailing edge myth) can be easily derived from Newtons Equation with a few basic assumptions (ideal gas being the primary one), so there is really no difference and both can be used to model / calculate lift and both give exactly the same answers.
Click to expand...
Huge difference since streamline flow of a gas is required for Bernoulli. Newton just requires movement.
 
Tarheelpilot said:
Explain how the air buddies meeting at the trailing edge is a myth
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A) It violates Newtons Laws (aside from quantum mechanics and relativity, everything obeys Newtons Laws)
B) Airplanes as we know them couldn't fly if it were true.
C) Wind tunnel data clearly shows that it is false.
D) Flying upside down would be even more impossible than flying right side up.
E) Airplane wings would be flat on the bottom and curved on the top if the myth were true.
https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html
 
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Clark1961 said:
Huge difference since streamline flow of a gas is required for Bernoulli. Newton just requires movement.
Click to expand...
Yes, Bernoulli is a special case. But the calculations still work reasonably well for pressure distributions - and without pressure differences, there wouldn't be any force on the wing.

There is a bit of a chicken vs. egg thing, but...
 
Capt. Geoffrey Thorpe said:
Bernoulli's equation (the real equation - not the air buddies meeting at the trailing edge myth) can be easily derived from Newtons Equation with a few basic assumptions (ideal gas being the primary one), so there is really no difference and both can be used to model / calculate lift and both give exactly the same answers.
Click to expand...
Best answer right here. Everyone seems to treat Bernoulli's equation as some kind of independent law, but it's actually a consequence of Newton's laws with some additional assumptions. In the end, everything is either Newtonian, or obeys a more general law of which Newtonian physics is a limiting case.
 
Clark1961 said:
Do pepperoni slices add lift or drag?
Click to expand...

Pepperoni slices act as vortex generators, energizing the airflow, removing some of the slow moving boundry layer and improving lift. They also significantly add to the available supply of grease which can act as a de-icing mechanism.

Sausage, on the other hand, provides significant amounts of flavor, but, due to the lumpy morphology, tends to have a negative effect upon the aerodynamics of the pizza.

And although no one has yet brought up the effects of pineapple chunks on the pizza’s aerodynamics, let me just clearly state that adding pineapple to a pizza is just plain wrong.


Sent from my iPad using Tapatalk
 
Bernoulli said it, I believe it, and that settles it.
 
An airplane wing stalls when the critical angle of attack is exceeded and airflow separates from the top of the wing. I don't see how you can explain that without the Bernoulli effect. :confused2:
 
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