Why Planes Fly: What They Taught You In School Was Wrong

Posted on October 22, 2007  Comments (3)

Why Planes Fly: What They Taught You In School Was Wrong

So we all know how planes fly, right? The top of the wing is rounded and the bottom of the wing is more straight. Air takes longer to travel over the top of the wing than the bottom, which results in more pressure on the bottom, hence the lift. Right? As it turns out, no.

This is what I was taught, and it’s what I’ve always believed (it’s even in most lower-level text books), but it’s simply not true. The concept is called the Bernoulli Principle, and it accounts for very little of the lift that makes flight possible. The main reason planes fly is far simpler: wings force air downward, which in turn pushes the wings upward.

The primary actor here is the the Coanda Effect, with the Bernoulli Principle taking a supporting role. It all starts with the air wrapping downward along the back of the wing (Coanda).

Related: The Silent Aircraft InitiativeEngineering the Boarding of Airplanes

3 Responses to “Why Planes Fly: What They Taught You In School Was Wrong”

  1. Curious Cat Science and Engineering Blog » Successful Emergency Plane Landing in the Hudson River
    January 15th, 2009 @ 6:56 pm

    [...] Why Planes Fly: What They Taught You In School Was Wrong – Engineering the Boarding of Airplanes by curiouscat   Tags: Engineering   [...]

  2. Curious Cat Science and Engineering Blog » Why Planes Need to Avoid Fine Volcanic Ash
    April 15th, 2010 @ 7:00 pm

    “Aircraft avoid any airspace that has volcanic ash in it for a simple reason: the ash can wreck the function of propeller or jet aircraft, because it is so fine [less than 2mm in diameter, and some as fine as 6 microns] that it will invade the spaces between rotating machinery and jam it..”

  3. Dave
    April 16th, 2010 @ 2:00 pm

    I remember having this arguement with my physics professors in college many many years ago. I was told I was wrong and ignorant. I’m glad that it only took about 45 years for theme to get it right. Bernoulli’s principle doesn’t apply at all to modern high speed wings with diamond cross sections or to some of the old time flat surface wings. But somehow theyse wings still fly.

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