Gurney flap

A Gurney flap shown on the underside of a Newman airfoil[1]

The Gurney flap (or wickerbill) is a small tab projecting from the trailing edge of a wing. Typically it is set at a right angle to the pressure-side surface of the airfoil[2] and projects 1% to 2% of the wing chord.[3] This trailing edge device can improve the performance of a simple airfoil to nearly the same level as a complex high-performance design.[4]

The device operates by increasing pressure on the pressure side, decreasing pressure on the suction side, and helping the boundary layer flow stay attached all the way to the trailing edge on the suction side of the airfoil.[5] Common applications occur in auto racing, helicopter horizontal stabilizers, and aircraft where high lift is essential, such as banner-towing airplanes.[6]

It is named for its inventor and developer, American race car driver Dan Gurney.[7][8]

  1. ^ Liebeck, Robert H. Design of Subsonic Airfoils for High Lift. Journal of Aircraft, Vol. 15, no. 9, September 1978, pp. 547-561.
  2. ^ Van Dam, C. P.; Yen, D. T.; Vijgen, P. (1999). "Gurney flap experiments on airfoil and wings". Journal of Aircraft. 36 (2): 484–486. doi:10.2514/2.2461. These devices provided an increased region of attached flow on a wing upper surface relative to the wing without the flaps.
  3. ^ Storms, B. L.; Jang, C. S. (1994). "Lift Enhancement of an Airfoil Using a Gurney Flap and Vortex Generators". Journal of Aircraft. 31 (3): 542–547. doi:10.2514/3.46528. One candidate technology is the Gurney flap, which consists of a small plate, on the order of 1–2% of the airfoil chord in height, located at the trailing edge perpendicular to the pressure side of the airfoil.
  4. ^ Giguere, P.; Lemay, J.; Dumas, G. (1995). "Gurney flap effects and scaling for low-speed airfoils". AIAA Applied Aerodynamics Conference, 13 th, San Diego, CA, Technical Papers. Pt. 2. pp. 966–976. through the proper use of Gurney flaps, the aerodynamic performance of a simple design, easy-to-build airfoil can be made practically as well as those of a modern, high performance, complex design.[permanent dead link‍]
  5. ^ Cite error: The named reference Myose1998 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Troolin2006 was invoked but never defined (see the help page).
  7. ^ "The Gurney Flap – Dan Gurney's All American Racers". allamericanracers.com. Retrieved 23 April 2018.
  8. ^ SEAS. "Gurney Flap". www.formula1-dictionary.net. Retrieved 23 April 2018.