Weekends

There was this fellow, Bernoulli, who in the 1700s figured out that the movement of a gas changes its pressure. Since a sail (or an airplane wing) is curved, air moves over its two surfaces at different speeds, generally faster over the outside of the curve, slower over the inside.



I read an article this week that says even a flat barn door can act as a wing, and that it is thus the angle of attack (the angle of the sail/wing relative to the direction of the air flow) rather than curvature that really matters. I ponder these matters from a hammock at the mouth of the Volta.