Utah State University College of Engineering
Mechanical & Aerospace Engineering

Warren F. Phillips

Mechanics of Flight
Wiley Store
Barnes & Noble
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Instructor's Companion Site
Reader's Companion Site

Technical Publications
CFD Validation
Media Coverage
Adam Aircraft
Prototype aircraft with operational twisterons and the wing tip vortex responsible for induced drag.

Warren F. Phillips
Mechanical & Aerospace Engineering
Utah State University
4130 Old Main Hill
Logan UT 84322-4130

Email: wfphillips@engineering.usu.edu
Phone: (435) 245-3614

United States Patent Number 6,970,773
A newly developed mathematical solution to a well-established theory of lifting wings has led to the development of improved technology that can significantly reduce the drag acting on an aircraft in subsonic flight. This drag reduction is accomplished through twisting the wing, or some portion of the wing, in a special manner that depends on wing shape and aircraft operating conditions. Of course twisting the wing of an aircraft is not new. Only eight years after the first unpowered human flight by Otto Lilienthal in 1891, and more than four years before their first powered flight in 1903, the Wright brothers began experimenting with wing twist as a means of controlling the rolling motion of an aircraft. Many hours of watching birds in flight led Wilbur to conclude that birds “regain their lateral balance, when partly overturned by a gust of wind, by a torsion of the tips of the wings.” This was one of the most important discoveries in aviation history. Less than two decades later, Ludwig Prandtl published the first theory of lifting wings, which allowed us to mathematically analyze and predict the effects of wing twist. In the 1920s, Hermann Glauert discovered from Prandtl’s theory that twisting the two sides of a wing in a symmetric manner could affect the drag acting on the wing. However, under some conditions wing twist was found to reduce the drag and for other conditions twist was found to increase the drag. The foundation of the recent technology improvement is a new analytical solution to Prandtl’s theory that allows us to predict and maintain the proper distribution and amount of wing twist, which is necessary to minimize an important component of aircraft drag. With modern sensors and flight computers, which are used on most aircraft today, this new mathematical solution can be incorporated in an active feedback control system to provide the capability for adjusting wing twist on-the-fly. In this manner minimum possible drag is always maintained as the environment and operating conditions change. This technology may eventually become one small part of a completely new generation of morphing aircraft that are capable of automatically adapting to a changing set of environmental conditions and mission requirements.