Відео

Didn't think it was obvious at all until the le closes up. Incredible stuff

@jacksonsingleton As the slat extends, watch the somke lines transition from a downward path to an upward one.

Wouldn’t it make no difference whether the airfoil is moving relative to the air, or if the air is moving relative to the airfoil? I am pretty sure that these 2 cases are equivalent. Please correct me if I am wrong.

@@mismis3153 For an airfoil/wing to generate appreciable lift, IT must be moving relative to the air. If it is not, no vacuum is created on the backside of the airfoil to pull down (“scoop”) and accelerate air from above to create lift. In a wind tunnel the AIR is moving relative to the airfoil: No backside vacuum, no scooping of air, no acceleration of air downward, so little to no lift. Anderson’s “Understanding Flight” is a good resource. There are vids of jumbos landing in certain atmospheric conditions where the “scooping” and accelerated air down the trailing edge is visible. Another fact: Airfoils/wing derive the vast majority of the energy that sustains flight from gravity. Unpowered glide ratios, autorotation, autogyros, etc. the proof.

but the airfoil is moving relative to the air

@@sgtjonzo The airfoil is not moving. Therefore no vacuum can form on the upper-rear of the airfoil to generate lift. It is the interaction of a MOVING airfoil with air that generates lift, NOT the movement of air over an airfoil. There are videos of jumbos landing where condensation is seen in the low pressure zone above the jumbos’ airfoils/wings. Even better are the ones that show the so scooped and accelerated air blasting down the airfoils’/wings’ trailing edge.