PRANDTL_065
Flow visualization using a laser light sheet. Laser light is spread out into a wide thin light sheet. Optics create this sheet of light just behind the model. The camera is aimed forward along the sting mount holding the model at its centerline (visible at the right edge of both images), and the left wing tip of the Preliminary Research Aerodynamic Design to Lower Drag (Prandtl-D) model is illuminated (at the right edge of the image). Smoke is injected into the flow in front of the model, and the behavior of the smoke is seen where the smoke crosses the laser light sheet. The blob in this image is a “(” shaped smoke, this smoke is on the outboard of the wing vortex. This is an unusual characteristic as most aircraft wings create their wing vortices at the wingtips, and not along the span of the the wings. This is a unique characteristic of the Prandtl wings that we have intentionally designed into them; to reduce the drag and to create the flight behavior that allows these wings to fly like birds fly without vertical tails.
2015
Submitted photo courtesy of G. Lee Pollard