Flying Upside-Down
Part of the fascination of an aerobatics display is that with loops and upside-down flight. If the greater curvature on top of the wing and the
Bernoulli effect are evoked to explain lift, how is this possible? The illustrations below attempt to show that an increase in airstream velocity over the top of the wing can be achieved with airfoil surface in the upright or inverted position. It requires adjustment of the
angle of attack, but as clearly demonstrated in almost every air show, it can be done.
Similar sketches can show the conditions for lift on a
symmetric airfoil. While the typical asymmetric shape of an
airfoil make increase
efficiency of lift production in its upright position, the asymmetry of the
airfoil is not essential for
producing lift.