Brat's Weave Of Madness

Physics 101: Flight
Friday, April 18, 2008

Well, I thought it was about time that I did some good with my blog, so here's the good... Physics was pretty much my favorite science subject in high school, and you'd be amazed at all the things Physics controls and how incredibly interesting it can be...

So your first Physics 101 lesson... Flight... And if you've always wondered how airplanes fly, well, I'm here to tell you that it's NOT because of the engine, although the engine plays a role... Think of it this way, if you took a great massive engine, and you bolted it onto, say a barn door... You wouldn't have an airplane so much as a mess...

So the secret to flight? The wing... It's all in the wing of the airplane, and the rest is just simple aerodynamics and laws of motion... Contrary to what you may have thought, the wing of an airplane is not flat, and neither is it symmetrical (except for a few exceptions)... It looks more like the picture on the left...

So from the picture on the left, you can see that the top of the wing is curved lots, while the bottom is predominantly flat... Of course there are a great many variety of wings, and you'll find symmetrical ones too (on aerobatic planes)... But for the purpose of this discussion (and to cover all modern airliners) we'll talk about the flat bottom wing... So flight needs to be based on a theory... And that theory is Bernoulli's Theorem...

Bernoulli's Theorem states that the greater the velocity of air, the lower the amount of pressure it exerts... Basically, the faster air moves, the lower pressure it has on objects around it... I must say here that the picture is not entirely accurate... Specifically, the first bit, where it says "...greater distance to travel, and must move faster.." The thing is, air does not actually do any such thing... The air on the bottom is actually slower than the air on top because the air on top creates a vortex that works against the air at the bottom... But for now, just know that the air at the bottom is slower than the air that is going above the wing... So now, because of the shape of the wing, the air under the wing travels at a slow speed, and thus the pressure is higher than the pressure of air on top of the wing. So we have a high pressure zone below the wing, and a low pressure zone above the wing... There's a blanket of air under the wing, and no blanket above it... So the wing rises... An interesting fact is that if you increased the throttle of an airplane sitting on the runway, and did nothing else at all, then after a while the airplane would automatically lift of the ground... no hands :)

So again, Why is the wing important? Because when you get in an airplane, you generally want to be moving in one or both of two directions, namely, forward... and up... GENERALLY i said... don't start giving me crap about landing patterns and helicopters... So there are four forces acting on an airplane... And the picture pretty much explains it... The wing produces lift, against gravity... While the engine (the other important bit) produces thrust to move the plane forward, against drag, which is created by air particles and acts upon anything except itself...

So it's pretty obvious that drag is much less for a smaller leading cross section. That's why airplanes have noses and look cool :) Because their shapes are designed to minimize drag... Consider this... If you put your hand out the window of a fast car, the only way you'd meet the least resistance from air was if you made it flat.. just like an airplane.. try it otherwise... much harder isn't it?

Right-o... So what's the need for the rest of the stuff on the plane? Like the flaps, slats, air brakes (i think that one's obvious), ailerons, elevators (again.. obvious) and the tail? Well, it's all quite simple and every single little thing is important and quite extraordinary... But I'm afraid that's pretty much all I can type out right now... So Await your next installment of Physics 101...

And let me know if you want to hear about all the other crap... And I promise I will write.. not like the other stuff I've promised (*cough*India*cough*)...

And tell me if this is a crap idea!! :)

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