Although the study of Aerodynamics has been a done deal for quite some time, I still wonder about a few things. Most likely my lack of understanding is at fault.

Lift is created by a drop in pressure when air travels faster over the top of the wing. It’s said that the distance between air molecules above the wing is greater (less of them) than below. This localized “lighter air” on top of the wing allows the greater pressure below the wing to push upward on it creating lift.

They claim the same principle holds true for a hydrofoil. I just can’t imagine water being pulled apart on top of the hydrofoil causing a pressure drop.

Intuitively, lift appears to be created by the angle of the wing (pitch) and Newton’s third law.

When you were a kid did you ever fly balsa wood gliders? They flew great and their wings were perfectly flat.

Have you ever noticed the flaps on a 747 when it lands? Don’t they create added lift by pushing downward on the airflow?

We all have placed our hands out the car window and tilted them up and down. Remember what happens?

You could probably demonstrate lift by pulling a wing through sand. How could say the lift was caused by a pressure drop?

Look atTom’s post about Sangers’ designs. Notice the angle of the rotors on the Triebflugel. It’s more like a big propeller. By the way, aren’t propellers designed to pull or push the craft through the air. They don’t do it by creating negative pressure in front of themselves ….

Or do they?