Added: 2 years ago
From: draftblader
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  • Air, going over the top of a convex wing, is not travelling faster but, instead, slower. It slows even more when required to travel (flow) over an extended surface such as flats & slats. The slower the speed the more negative air pressure, the more lift which is created from events on the top, rather than the bottom, of the wing. Right?

  • The region of high pressure is between your lips and the microphone. Move it away from your mouth next time.

  • The airfoil statement is wrong, but good job though!

  • I recommend "A Physical Description of Flight; Revisited" if you're interested.

  • Bernoulli's equation applies to flows with no work. You're airfoil explanation relies on the theory of equal transit times which is wrong...The shape of the wing influences stall characteristics. A flat plate or even the wing you showed if turned upside down will fly. It's about diverting air down and Newton's laws not Bernoulli. I recommend reading this if you're really interested.

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  • @dmartinez95 While this is true, the Bernoulli principle is still in effect when a wing is completely level, and there is no downward deflection.

    I think there are way too many fans of specific "camps" in aerodynamics and wing lift theory. In the end it's the combination of much lower pressure on top than on the bottom of the wing. Deflection, Bernoulli effect, and the Coanda effect are all in play here at the same time.

  • @mobius1aic An upside down wing requires a very significant α in order to influence the fluid to travel faster along it's "top". Aerobatics aircraft tend to have the teardrop airfoil shape since it's a relatively symmetrical airfoil that can allow for the plane to fly upside down without much trouble. Normal level flight requires the wing to have a small +α, so it's installation on the aircraft tends to be within the 10° region judging by it's chord.

  • @mobius1aic Aircraft moving relatively fast enough to have the wing at 0°/low α in level flight will be flying on lift developed via the Bernoulli principle, not deflection.

  • @mobius1aic It is however completely correct that the "equal transit time" is a misguided answer as to why air going over the top of the wing is moving faster. From what I understand, it's more or less the compression and deflection of air as it hits the curve/edge that forces it to increase it's velocity as the wing slices through it, in a diffusive manner.

  • Obviously you don't row boats very much. Enjoyed the hair dryer thing but the wing is oversimplified. The leading edge is active and leads to the air traversing the top section significantly faster than that below. I wonder how much of the physics you understand.

  • @ToReSnipin Bronoulli drives a lifted Toyota Tacoma and drinks hella natty...

  • I thought the boat would go to the left in the example due to the paddle action. I guess it depends on the boat a bit

  • nice one dude

  • thanks! really helpful :)

  • cheers dude

  • really nice dude i tried the whole time to get it .although i´m actually german i have understood your video!

    So thanks a lot dude^^

  • Sorry, but at least the part about wings is wrong. The air split by the wing does NOT meet again at the end of the wing. The shape of a wing is mainly to provide lift over a wide range of angles of attack and reduce drag at the same time.

    How else would you explain that paper planes can fly while having a completely flat wing surface at top AND bottom?

  • @superdau Dude, it does meet back. At certain time, they will meet back if the angle of attack is zero. So theorically, we make an assumption that they do meet back.

    And another thing is, dude that's paper plane. You use your momentum to fly it. Lulz do you ever made a paper plane that can really fly about 10 minutes? not even 1 minute. so think about it.

  • @AsyrafRCKS

    You didn't get it. Of course there's no vacuum behind a wing. But the air molecules right above each other before the split DON'T meet again at the trailing edge of the wing. The arrows moving at the same speed above and below the wing imply that. The argument then is: because the upper curve is longer, the air has to move faster. Which is totally wrong, because there's no law that dictates the same molecules have to meet again after the wing.

  • @superdau

    You are right, this incorrect theory is shown everywhere, even in some reference books. The real explanation comes from Euler and Navier-Stoke equations and agree with both Bernoulli and Newtons laws (energy and momentum conservation).

  • @AsyrafRCKS

    I don't get your logic and it seems you aren't good at building paper planes. First i have made paper planes that flew longer than a minute. Second why do you compare a plane with engines with one without engines. How many planes have you seen that can fly without thrust?? Turn off the engines of a jet plane and see how far it gets. A jet plane can go about 10km for every km it descends without thrust. Paper planes can have a lower descent rate than that.

  • Looking at your air video and looking at the roof box on my car I was wondering have the manufacturer got it facing the wrong way i.e. with the largest end at the rear of the roof (probably causing drag) and the wedge shape at the front of the car. I know it will look stupid with the big end facing forward and if will take a brave man to drive his car down the street and with it facing like an air-foil. Am I missing something with this air foil thingy!!

  • @itsmefergal Ye, the wheels.

  • annoying to listen too

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