Lift per unit span = ρ × V × Γ Where ρ is density, V is freestream velocity, and Γ is circulation.
A wing is not a "suction machine." The low pressure on top is caused by the air following a curved path. For a fluid parcel to move in a curve, there must be a net inward force (centripetal force). That force comes from a pressure difference: lower pressure toward the center of curvature. The top of the wing is the center of curvature, so pressure drops. Section 4: The Circulation Explanation (The Mathematically Honest Version) In advanced physics, we use circulation (Γ). This is not a fiction; it is a measurable quantity: the line integral of velocity around a closed loop enclosing the wing. understanding aerodynamics arguing from the real physics pdf
"Force equals the rate of change of momentum." This is the only direct cause of aerodynamic force. For a wing to experience an upward force (lift), it must impart a downward change of momentum to the air. Lift is the reaction to turning the flow downward. Lift per unit span = ρ × V
Understanding Aerodynamics: Arguing from the Real Physics That force comes from a pressure difference: lower
Do not settle for stories that feel good. Test every explanation against Newton’s laws and the conservation of mass. If an explanation cannot account for a flat plate flying upside-down, discard it. Real aerodynamics is not magic; it is the beautiful, inevitable consequence of a solid object moving through a fluid that must obey three simple rules. Master those rules, and you master the air.