Kylie Irving: The Earth is Flat

ThreatMatrix

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He does. Just go look at your school books back then if you are up in age a little and see how many false things were said about the universe, galaxy and even the solar system back then.
:shocked:
Are you suggesting that some times scientists get it wrong.

 

Gator2222

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Schools still teach things that are untrue simply because of tradition or because it's easier.

Two prominent examples.

Almost everything you learned in school about George Washington is untrue to some extent. They won't teach kids that Washington was the largest distiller of liquor in the US, his false teeth weren't wood, that while he was a great general he lost the vast majority of his battles and that a very good case can be made that Washington was not the first president of the United States. If you ever go to the Smithsonian Museum of American History you can see a letter that George Washington wrote to John Hanson congratulating him on becoming the first president of the United States. Washington was actually number nine.

Flight schools commonly teach pilots Bernoulli's principle and "equal transit-time" as the primary reason planes are able to fly. They do this despite the fact that Bernoulli's principle is used to explain fluid dynamics and is incorrectly used to explain lift.
 
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Gatordiddy

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Don't let him fool you - he's one of these

ed248939a65a81525440738466a5e245.jpg
 

Gator2222

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He's a commercial pilot and former Marine Fighter pilot.

God bless him. Always grateful for those who serve.

It appears that he is gone for a while, but I will expound as requested anyway.

I used to have a next door neighbor who was an international pilot for Delta. I also have a friend that owns a plane and has a license. One evening when we were all hanging out the two of them started talking about flight school and flying in general. They both rolled their eyes when Bernoulli's principle came up. I knew the basics of the science, but did not know the nuances. I had been taught equal transit time in physics classes.

They explained to me that in flight school they were taught Bernoulli's principle and equal transit time as the science behind lift. One of them questioned the instructor and told him that equal transit time was known to be incorrect. Apparently, the instructor agreed that it was wrong, but insisted it was still the best way to teach people because it was easier to understand.

It's always stuck with me as really odd that people would teach something they know is not correct.
 

Zambo

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Are you a pilot? Did they teach you equal transit time in flight school?
Yes I've been flying professionally for 24 years.

When you drink out of a straw, aren't you sucking the coke into your mouth? Well an engineer might point out that actually what you are doing is creating a low pressure area above the drink and allowing the high pressure atmosphere around the drink to force the fluid up the straw and into your mouth. Does this make the original statement wrong? Not really, it just expounds upon it and goes into more detail.

Equal transit time IMO is simply an incorrect inference. The air going over the top of the wing is certainly moving faster and creating lower pressure (and resulting in lift) than the air going under the wing. I don't think that two adjacent molecules splitting up at the front of a wing and rejoining at the trailing edge of the wing was the thrust of how Bernoulli principle was explained to me way back when. Bernoulli certainly applies to airflow since air is a fluid. Where geeks go crazy is thinking that the shape of the wing is the only thing creating differential pressure. Heck, an isosceles triangle has a flat bottom and a longer path on top but it certainly wouldn't create enough lift to fly by running it quickly through the atmosphere. The real story is that the air going over the wing not only travels faster than the air going underneath, but in fact much faster than would be calculated simply by measuring the distance from the leading edge to the trailing edge and dividing by the speed.

The high pressure air underneath and the low pressure air on top are affected by the shape, but also by the angle of attack. By rotating the wing in relation to the incoming air, you are effectively changing the shape of the wing with regard to how air flows over it. The point where the oncoming air hits the leading edge of the wing gets lower as the angle increases, which effectively makes the air going over the top travel an even greater distance than a wing with a lower angle of attack, thereby increasing the pressure differential and increasing lift.

This is the point where the drinking straw naysayers would point out that the "wings" of an airplane are not all designed like the main wing with a flat bottom and a curved top. I say this because not all "wings" as you probably know are designed for one way lift like the main wing of an airplane. The rudder, stabilizer, and other types of airfoils need to turn in both directions and are symmetrical in crosssection....so the only way they make lift is by changing AOA. But if AOA was the sole creator of lift, then the main wing wouldn't be shaped like it is with a mostly flat bottom and a curved top. So how can some planes fly upside down? Well they simply generate enough AOA in the opposite direction from the natural lift direction to overcome those little Bernoullis zipping over the wings surface. I can promise that a fighter, with its thin, high speed wing, is a lot more nose up when flying inverted than it would be flying at the same speed while upright. The best way to think of AOA and lift is by imagining sticking your hand flat out of a car window and then angling it up and down....the wind makes your arm want to climb and descend. But just like the soda straw geeks, I could draw a diagram of how tilting your hand to change the angle of attack simply creates high pressure on one side of your hand and low pressure on the other. Its just easier to think of it as the wind hitting one side of your hand and not the other.

None of what I just typed means that the idea of Bernoulli's law creating lift is false. Its just not the whole enchilada of flying. I would hardly call the use the simplified explanation of lift to gradeschool students and laypersons a fallacy. Certainly not on the level of whether the earth is flat or not.
 

ThreatMatrix

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God bless him. Always grateful for those who serve.

It appears that he is gone for a while, but I will expound as requested anyway.

I used to have a next door neighbor who was an international pilot for Delta. I also have a friend that owns a plane and has a license. One evening when we were all hanging out the two of them started talking about flight school and flying in general. They both rolled their eyes when Bernoulli's principle came up. I knew the basics of the science, but did not know the nuances. I had been taught equal transit time in physics classes.

They explained to me that in flight school they were taught Bernoulli's principle and equal transit time as the science behind lift. One of them questioned the instructor and told him that equal transit time was known to be incorrect. Apparently, the instructor agreed that it was wrong, but insisted it was still the best way to teach people because it was easier to understand.

It's always stuck with me as really odd that people would teach something they know is not correct.

Technically you're correct.
https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html

But it's probably not the best example. As a private pilot myself we were taught "longer path/equal transit". Not that it mattered much as we weren't designing wings just hoping to keep the plane in the air.
 

GatorJ

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Yes I've been flying professionally for 24 years.

When you drink out of a straw, aren't you sucking the coke into your mouth? Well an engineer might point out that actually what you are doing is creating a low pressure area above the drink and allowing the high pressure atmosphere around the drink to force the fluid up the straw and into your mouth. Does this make the original statement wrong? Not really, it just expounds upon it and goes into more detail.

Equal transit time IMO is simply an incorrect inference. The air going over the top of the wing is certainly moving faster and creating lower pressure (and resulting in lift) than the air going under the wing. I don't think that two adjacent molecules splitting up at the front of a wing and rejoining at the trailing edge of the wing was the thrust of how Bernoulli principle was explained to me way back when. Bernoulli certainly applies to airflow since air is a fluid. Where geeks go crazy is thinking that the shape of the wing is the only thing creating differential pressure. Heck, an isosceles triangle has a flat bottom and a longer path on top but it certainly wouldn't create enough lift to fly by running it quickly through the atmosphere. The real story is that the air going over the wing not only travels faster than the air going underneath, but in fact much faster than would be calculated simply by measuring the distance from the leading edge to the trailing edge and dividing by the speed.

The high pressure air underneath and the low pressure air on top are affected by the shape, but also by the angle of attack. By rotating the wing in relation to the incoming air, you are effectively changing the shape of the wing with regard to how air flows over it. The point where the oncoming air hits the leading edge of the wing gets lower as the angle increases, which effectively makes the air going over the top travel an even greater distance than a wing with a lower angle of attack, thereby increasing the pressure differential and increasing lift.

This is the point where the drinking straw naysayers would point out that the "wings" of an airplane are not all designed like the main wing with a flat bottom and a curved top. I say this because not all "wings" as you probably know are designed for one way lift like the main wing of an airplane. The rudder, stabilizer, and other types of airfoils need to turn in both directions and are symmetrical in crosssection....so the only way they make lift is by changing AOA. But if AOA was the sole creator of lift, then the main wing wouldn't be shaped like it is with a mostly flat bottom and a curved top. So how can some planes fly upside down? Well they simply generate enough AOA in the opposite direction from the natural lift direction to overcome those little Bernoullis zipping over the wings surface. I can promise that a fighter, with its thin, high speed wing, is a lot more nose up when flying inverted than it would be flying at the same speed while upright. The best way to think of AOA and lift is by imagining sticking your hand flat out of a car window and then angling it up and down....the wind makes your arm want to climb and descend. But just like the soda straw geeks, I could draw a diagram of how tilting your hand to change the angle of attack simply creates high pressure on one side of your hand and low pressure on the other. Its just easier to think of it as the wind hitting one side of your hand and not the other.

None of what I just typed means that the idea of Bernoulli's law creating lift is false. Its just not the whole enchilada of flying. I would hardly call the use the simplified explanation of lift to gradeschool students and laypersons a fallacy. Certainly not on the level of whether the earth is flat or not.

AE1F01DE-F97A-4AFD-842B-389BFD6F1C49_zpsxte2yvdf.gif
 

Gator2222

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Technically you're correct.
https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html

But it's probably not the best example. As a private pilot myself we were taught "longer path/equal transit". Not that it mattered much as we weren't designing wings just hoping to keep the plane in the air.

"longer path/equal transit" is exactly what I was referring to in my post. It's technically not correct and yet still taught.

I'm still amazed that the Bernoulli's principle part garnered more interest than Washington not being the first president. LOL.
 

ThreatMatrix

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"longer path/equal transit" is exactly what I was referring to in my post. It's technically not correct and yet still taught.

I'm still amazed that the Bernoulli's principle part garnered more interest than Washington not being the first president. LOL.

FWIW I never agreed with Bernoulli on principle. :dance:
 

Gator2222

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Yes I've been flying professionally for 24 years.

When you drink out of a straw, aren't you sucking the coke into your mouth? Well an engineer might point out that actually what you are doing is creating a low pressure area above the drink and allowing the high pressure atmosphere around the drink to force the fluid up the straw and into your mouth. Does this make the original statement wrong? Not really, it just expounds upon it and goes into more detail.

Equal transit time IMO is simply an incorrect inference. The air going over the top of the wing is certainly moving faster and creating lower pressure (and resulting in lift) than the air going under the wing. I don't think that two adjacent molecules splitting up at the front of a wing and rejoining at the trailing edge of the wing was the thrust of how Bernoulli principle was explained to me way back when. Bernoulli certainly applies to airflow since air is a fluid. Where geeks go crazy is thinking that the shape of the wing is the only thing creating differential pressure. Heck, an isosceles triangle has a flat bottom and a longer path on top but it certainly wouldn't create enough lift to fly by running it quickly through the atmosphere. The real story is that the air going over the wing not only travels faster than the air going underneath, but in fact much faster than would be calculated simply by measuring the distance from the leading edge to the trailing edge and dividing by the speed.

The high pressure air underneath and the low pressure air on top are affected by the shape, but also by the angle of attack. By rotating the wing in relation to the incoming air, you are effectively changing the shape of the wing with regard to how air flows over it. The point where the oncoming air hits the leading edge of the wing gets lower as the angle increases, which effectively makes the air going over the top travel an even greater distance than a wing with a lower angle of attack, thereby increasing the pressure differential and increasing lift.

This is the point where the drinking straw naysayers would point out that the "wings" of an airplane are not all designed like the main wing with a flat bottom and a curved top. I say this because not all "wings" as you probably know are designed for one way lift like the main wing of an airplane. The rudder, stabilizer, and other types of airfoils need to turn in both directions and are symmetrical in crosssection....so the only way they make lift is by changing AOA. But if AOA was the sole creator of lift, then the main wing wouldn't be shaped like it is with a mostly flat bottom and a curved top. So how can some planes fly upside down? Well they simply generate enough AOA in the opposite direction from the natural lift direction to overcome those little Bernoullis zipping over the wings surface. I can promise that a fighter, with its thin, high speed wing, is a lot more nose up when flying inverted than it would be flying at the same speed while upright. The best way to think of AOA and lift is by imagining sticking your hand flat out of a car window and then angling it up and down....the wind makes your arm want to climb and descend. But just like the soda straw geeks, I could draw a diagram of how tilting your hand to change the angle of attack simply creates high pressure on one side of your hand and low pressure on the other. Its just easier to think of it as the wind hitting one side of your hand and not the other.

None of what I just typed means that the idea of Bernoulli's law creating lift is false. Its just not the whole enchilada of flying. I would hardly call the use the simplified explanation of lift to gradeschool students and laypersons a fallacy. Certainly not on the level of whether the earth is flat or not.

That's a great way of explaining the forces at work. I have always found physics fascinating. It just seems odd to me that they don't drop the equal transit time when explaining the theory. It's been proven that it isn't necessary for the molecules to reach the trailing edge at the same moment. It seems like a weird thing to keep alive.
 

Gatordiddy

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I'm still amazed that the Bernoulli's principle part garnered more interest than Washington not being the first president. LOL.

"Many people have argued that John Hanson, and not George Washington, was the first President of the United States, but this is not quite true. Under the Articles of Confederation, the predecessor to the US Constitution, the United States had no executive branch. The President of Congress was a ceremonial position within the Confederation Congress. Although the office required Hanson to deal with correspondence and sign official documents, it wasn't the sort of work that any President of the United States under the Constitution would have done."

https://www.constitutionfacts.com/us-articles-of-confederation/john-hanson-story/
 

Zambo

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That's a great way of explaining the forces at work. I have always found physics fascinating. It just seems odd to me that they don't drop the equal transit time when explaining the theory. It's been proven that it isn't necessary for the molecules to reach the trailing edge at the same moment. It seems like a weird thing to keep alive.
I think it's just easier for people to visualize the concept. If you take it beyond that you have to really start getting into the weeds of how an airfoil actually works. I think the equal time model is more for explaining Bernoulli than it is for explaining lift. Bernoulli and lift are not exactly the same thing.
 

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