Flying wings are nothing new in aerospace, the Soviet Union began designing and building them in 1946 — the Horten brothers from Germany and aerospace companies from United States, Russia, France and United Kingdom have built them; however, none are designed quite like the Prandtl-D.
“I wanted to figure out how birds can fly without vertical tails,” says Albion Bowers, chief scientist at NASA Armstrong. He studied birds and discovered it was all in the curve, twist and bend of their wings, and so he designed a model with just the right “twists” — called the Preliminary Research Aerodynamic Design to lower Drag, or more commonly referred to as Prandtl-D.
Working with interns for several years, Bowers and his team are now flight testing their third model of a flying wing that could possibly change the future of aviation by making aircraft more aerodynamic. His design may also be used in exploring Mars.
“One of the unique things about this wing is that unlike a normal aircraft that sheds vortices (the major component of turbulent flow) at the wingtip, this wing sheds about 75 percent of the way out,” explains Robert “Red” Jensen, UAS chief pilot and master UAS technician. “By getting the vortex to shed further inboard, we are realizing a similar benefit to a winglet, but to a greater extent, something on the order of an 11 percent reduction in induced drag.”
Acceleration data — roll, pitch, yaw, speed and altitude — is collected by a cell phone strapped onto the wing. Recycled video tape is secured to the wing to visually inspect the inboard vortex.
“The testing today was fantastic,” said Jensen, “the aircraft performed as expected and we accomplished our goal of analyzing the flow visualization of the inboard vortex.”