Why airplanes fly, curveballs curve and the shower curtains sucks to your leg.

Welcome to the first post of our musings about the machines that excite us.  We wanted to create a place where we can kick back, crack a beer and tell stories of adventure or geek out about how things work.  The stories may only be mostly true and the technical explanations not perfectly accurate but we will do our best to keep it entertaining and sometimes informative.  We are glad to have you on board for the ride.

This is a pretty basic subject to most of our pilot friends but we thought we would start out with an attempt to explain how airplanes fly.  To do this we need to talk about two principles that are utilized when designing an aircraft.

First, to make a point, inhale deeply and then blow out. You would realize that you pressed your lips together to make a small hole for the air to flow through. You instinctively applied the Venturi Effect, increasing the speed of air by constraining the area though which it flowed. This is the first principle to allow airplanes to fly: Air velocity will increase as it moves through a constriction. To keep things simple think of the wing as your bottom lip with the air accelerating over the top.

The second principle that allows flight is called the Bernoulli principle. This principle says that the air pressure on a surface is lowered as the air velocity is increased over that surface. The faster the air moves over a surface the lower the air pressure on that surface.

So, again imagine the wing as your lower lip with the air velocity over the top of the wing faster than the bottom of the wing. Since the speed of air over the top of the wing is greater than the bottom the pressure is less on the top than the bottom. The pressure is greater on the bottom of the wing compared to the top and the wing is “pushed” upwards and thus is flying.

The same principle works for a curve ball. Since the pitcher puts side spin on the ball, as the ball moves towards home plate, one side of the ball has greater airflow compared to the other side of the ball. This difference in air velocity on each side of the ball causes a higher pressure on one side of the ball and a lower pressure the other side. This difference in pressure causes a “push” which pitchers call a curve. The same principles apply to a “slider” and “sinker” too.

What about that annoying plastic shower curtain that sucks in and sticks to your leg. As the water falls from the shower head to the shower floor the air is accelerated inside the shower. The velocity difference between the inside compared to the outside of the shower causes the pressure difference that moves the curtain inwards, and to stick to your leg.

If you have any corrections, bitches or gripes go ahead and fire at us.  We appreciate having you here and welcome the discussion.

 

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