Winglets

The wings of jet airplanes started to look different in the late 1980s. Instead of the abrupt “sawn off” tip of the Boeing 707, narrow upturned tips called winglets were introduced. The wings of many birds—such as the Caspian Tern (below)—show similar shapes during flight.

Caspian Tern (Hydroprogne caspia)  Lopez Island, WA. August. Photographer: Peter Cavanagh

Caspian Tern (Hydroprogne caspia) Lopez Island, WA. August. Photographer: Peter Cavanagh

In both birds and airplanes, the winglet increases lift and reduces drag on the wing by reducing the turbulence generated at the wing tip.

The tern’s wing is flat at rest (see wing in the display case at the exhibit) but bends to form the winglet during the downstroke. The Caspian Tern benefits from the reduced drag during its migratory flight in the fall.

Retrofitted winglet on a Boeing 727

Retrofitted winglet on a Boeing 727

The photograph above shows the wingtip of a converted 727 that is used by NASA for parabolic flight maneuvers. Like many other models, this airplane was retrofitted with winglets. Current blended winglets are estimated to save 4-6% in fuel costs and also to reduce noise compared to a straight tip.

LEARN MORE ABOUT CASPIAN TERNS

KIDS QUESTION: In the museum exhibit, we asked: What is the bird in the above picture carrying?

The answer is: A fish that it has just caught
The tern is carrying a sculpin that is has caught by plunge diving – bill first – in the shallow waters of Fisherman Bay on Lopez Island, WA.