the wing stops making lift and stalls. In other words, it stops flying.
More speed means more lift. But more lift is not necessarily better. Lift creates drag, which holds the wing and the airplane back. And drag increases much faster than the speed. When the airplane doubles its speed, the drag created by the wing quadruples! So more and more power is needed to go faster, in spite of the lift.
small angle, small lift
larger angle, more lift
too large an angle, no lift
know what?
Sometimes people say you can feel lift and drag for yourself by putting your hand out the window of a moving car. It’s true, but it isn’t a safe thing to do. Instead, try putting your hand close to the hose of a vacuum cleaner. Does it suck your hand? That’s because the air pressure is lower inside the vacuum, just like the top of a wing, and the thicker air outside is pushing your hand. Turn your hand sideways to the flow and then back to flat again. Feel the difference? That’s drag.
Streamlining
THICK OR THIN?
Too many layers of paper folded up at the front make the wing too thick. Air can’t go around it smoothly, so it gets unstuck and turbulent at the back. A thinner (or more sharply creased) wing is much better. By the way, putting thick folds on the top side of the wing doesn’t work very well either!
It’s important for an airplane to be streamlined. It has to be smooth and slick to slip through the air easily. Sleek looking airplanes fly fast because they cut right through the air. Wings and airfoils need to be streamlined too.
The more streamlined awing is, the more easily air can move around it. A blunt plate is the worst. Not only does it practically stop the air, but the flow behind it is turbulent and messy. A half circle also makes turbulence, because the air can’t join up neatly behind it. Round is better, and flat is most streamlined of all. But remember, flat wings don’t make much lift either. So the best wing shape is the one with the least drag for the most lift. In paper airplanes, that is a thin wing with two or three layers at the front.
Balance...
No matter how amazing a plane looks, it won’t fly unless it has balance. No amount of wishing will do. Here’s why!
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