The question of whether to use winglets on a design is not at all straightforward. Close study of the papers is required to decide on the possible benefits for a specific application. This remains a close call on when a winglet is the best solution. The choice is not based solely on aerodynamics, and requires consideration of structures and stability and control as well.
Richard T. Whitcomb, “A Design Approach and Selected Wind-Tunnel Results at High Subsonic Speeds for Wing-Tip Mounted Winglets,” NASA TN D-8260, July 1976.
Kichio K. Ishimitsu, “Aerodynamic Design and Analysis of Winglets,” AIAA Paper 76-940, Sept. 1976.
Lawrence C. Montoya, Stuart G. Fletcher and Peter F. Jacobs, “Effect of Winglets on a First-Generation Jet Transport Wing,” II - Pressure and Spanwise Load Distributions for a Semispan Model at High Subsonic Speeds, NASA TN D-8474, July 1977.
Harry H. Heyson, Gregory D. Riebe and Cynthia L. Fulton, “Theoretical Parametric Study of the Relative Advantages of Winglets and Wing-Tip Extensions,” NASA TP 1020, 1977.
P.T. Reynolds, W. M. Gersten and Voorhees, C. G., “Gates Learjet Model 28/29, the First "Longhorn Learjet,” AIAA Paper 78-1445, August 1978.
James F. Marchman III, David Manor, and Fred Faery, “Whitcomb Winglet applications to General Aviation Aircraft,” AIAA Paper 78-1478, Aug. 1978.
J.J. Spillman, “The use of tip sails to reduce vortex drag,” Aeronautical Journal, Sept. 1978, pp. 387-395.
J.J. Spillman, H.Y. Ratcliffe and A. McVitie, “Flight experiments to evaluate the effect of wing-tip sails on fuel consumption and handling charactersitics”, Aeronautical Journal, July 1979, pp. 279-281.
Norm Conley, “Winglet Toe-Out Angle Optimization for the Gates Learjet Longhorn Wing,” AIAA Paper 79-1832, August 1979, Journal of Aircraft, December 1980
Bruce J. Holmes, Cornelis P. van Dam, Philip W. Brown and Perry L. Deal, “Flight Evaluation of the Effect of Winglets on Performance and Handling Qualities of a Single-Engine General Aviation Airplane,” NASA TM 81892, December 1980.
John M. Kulhman, “Longitudinal Aerodynamic Characteristics of a Wing-Winglet Model Designed at M = 0.8, CL = 0.4 Using Linear Aerodynamic Theory,” NASA CR 172186, July 1983. This report includes lots of tabulated data.
Bruce Rosen, “Transonic Analysis of Canted Winglets,” AIAA Paper 84-0302, Jan. 1984.
Keisuke Asai, “Theoretical Considerations in the Aerodynamic Effectiveness of Winglets ” Journal of Aircraft, Vol. 22, No. 7, July 1985. This is probably the best discussion of the issues I've seen. My student Chris Johnston pointed this out to me.
John M. Kuhlman, M.J. Cerney and P. Liaw, “Transonic Low Aspect Ratio Wing-Winglet Design,” AIAA Paper 88-0007, Jan., 1988.
John M. Kuhlman, “Winglets on Low-Aspect-Ratio Wings,” Journal of Aircraft, Vol. 25, No. 10, Oct. 1988, pp. 932-941.
John M. Kuhlman, “Computational Design of Low Aspect Ratio Wing-Winglets for Transonic Wind-Tunnel Testing,” AIAA Paper 89-0644, Jan. 1989.
John M. Kuhlman, “Winglet Effectiveness on Low Aspect Ratio Wings at Supersonic Mach Numbers,” AIAA Paper 91-3305, Sept. 1991.
Tracy L. Bagwill and Bruce P. Selberg, “An Inviscid Aerodynamic Investigation of Wing/Winglet Geometries for RPV Application,” SAE Paper 941144, April, 1994.
R. Eppler, “Induced drag and winglets,” Aerospace Science and Technology, Jan. 1997, pp.3-15. An interesting paper. He includes profile drag also, and shows that with profile drag the net benefit of winglets may not be as large as expected from induced drag alone considerations.
Ilan Kroo, “Drag Due to Lift: Conceptsfor Prediction and Reduction,” Annual Review of Fluid Mechanics , Vol. 33, pp. 587-617, 2001. Another very good discussion of winglets, including the multidisciplinary design issues. A good list of references is included also.
Mark Maughmer, “The Design of Winglets for High-Performance Sailplanes,” AIAA Paper 2001-2406, June 2001.
M.J. Smith, N. Komerath, R. Ames, O. Wong and J. Pearson, “Performance Analysis of a Wing with Multiple Winglets,” AIAA Paper 2001-2407, June 2001.
Mark Maughmer, T.S. Swan and S.M. Willits, “The Design and Testing of a Winglet Airfoil for Low Speed Aircraft,” AIAA Paper 2001-2478, June 2001.
Neal Pfeiffer, “Numerical Winglet Optimization,” AIAA Paper 2004-0213, Jan, 2004. This paper includes profile drag in the optimization process.
Jean-Jacques Chattot, “Analysis and Design of Wings and Wing/Winglet Combinations at Low Speeds,” AIAA Paper 2004-0220, Jan. 2004. Very nice paper that includes computation of yaw effects and directional stability.
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direct comments and suggestions to W.H. Mason, whmason@vt.edu