Comment by bloppe
2 years ago
Ya, I was hoping for more nuance related to this. I'm sure the air foils generate lift, but atmospheric pressure at cruising altitude is ~4psi, and the pressure differential across the foil must be only a tiny fraction of that. According to my understanding of Bernoulli's principle, you'd have to quadruple the speed to cut the pressure in half, and I can't imagine the top air traveling that much faster than the bottom air.
Yet a 747 can produce 850000 pounds of lift with only 729000 square inches of wing? Feels like a very incomplete description at best
The pressure differential is what causes the direction change of the flow, pushing the air down. The shape of the wing and the angle of attack cause the pressure differential.
The airfoil shape causes formation of vortex around the wing, which ridiculously changes the relative speeds and pressures involved. At low pressure you compensate with speed, which is squared in lift equation.