NOW IT GETS A LITTLE WEIRD
Everyone likes the basic forces diagram we started this chapter with. However, things start to go off the rails when we look at cause and effect for lift. This is the part of fight I really like. There's still m to put your two cents in. It's far from settled science we're lead to believe it is. the first thing you need to know is that all science is really our best hunch about how the work. Pick any point in history and you'll find that about 90 percent of what was "known" at that time about how the universe worked was substantially incorrect. Here's another astounding thing. What we know is usually provable, depending on our ability to observe the thing we're studying. In other words, we're always limited by the tools we can bring to bear. We can't really understand germs and bacteria without a microscope. You can see the effects and come up with theories, but that's not quite the same. Our ability to probe the secret of flight is hampered by the nature of air and gravity. We can constantly see their effects, but they're generally invisible, For your amusement and contemplation, what follows are a couple of theories regarding the creation of lift--one of the most basic tenets of flight theory. Don't choke on the chalk dust.
A "BUNCH" OF LIFT?
Some aerodynamicists will argue another idea convincingly. I like this one slightly better. The that air kind of bunches up when it encounter the leading edge of the wing. That makes There's friction. Air gets slowed from the imperfections in the wing surface. Add the idea of a ved upper surface, and now the air is bunching up more on the top of the wing. Figure 16 illustrates this bunching effect. The bunching of the air causes a pressure difference further along the wing. The pressure is lower because the air is bunched up, or under higher pressure, just upstream. Now the air speeds up to fill the lower pressure and scoots off the trailing edge of the wing, ahead of the air on the bottom. The causal relationship is usually stated something like this: the lower pressure causes the faster moving stream of air. Note that this is exactly the opposite of the Bernoulli cause-and-effect statement.
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