In attempts to solve the mysteries of insect flight, scientists made enlarged scale models of bumblebee wings. These models produced viable results by combining the two essential forces in a fluida pressure force produced by fluid inertia, and a shear force caused by fluid viscosity. Professor Dickinson reported new findings of his own in 2001 as a result of building upon the theories of Ellington that he previously had attempted to refute. In his study published in Scientific American (Solving the Mystery of Insect Flight), Dickinson attributed the flight of the bumblebee to the phenomena of delayed stall, wake capture, and rotational circulation.

Delayed stall occurs when an aircrafts wing cuts through the air at too steep of an angle. Vortices created by airplanes usually leave behind a pestering turbulence in the slipstream. However, insects require these vortices to remain in flight. A vortex is a rotating flow of fluid, such as occurs in a draining bathtub. When proceeding at shallow angles, the air splits at the front of the wing and flows smoothly in two streams along the upper and lower surfaces. The upper flow travels faster, resulting in a lower pressure above the wing. This draws the wing upward, producing lift. The first stage of stall initially increases the lift because of a brief flow structure called a leading-edge vortex. This type of vortex forms directly above and behind the wings leading edge. Airflow in the vortex is extremely fast, and the resulting low pressure adds substantial lift.
The Flight of the Bumblebee
by Matthew Vanhorn