Flow Control and High-Lift Performance for Flying-Wing Unmanned Combat Air Vehicle Configurations by inserting slots


  • U Ali
  • E Chadwick




The objectives of the present study on Unmanned Combat Air Vehicles (UCAVs) are two-fold: first to control the flow by inserting leading-edge and cross-flow slots and analysing the viscous flow development over the outer panels of a flying-wing configuration to maximise the performance of the elevons control surfaces; second to predict high-lift performance particularly the maximum-lift characteristics. This is demonstrated using a variety of inviscid Vortex Lattice Method (VLM) and Euler, and viscous CFD Reynolds Averaged Navier-Stokes (RANS) methods. The computational results are validated against experiment measured in a wind tunnel. Two flying-wing planforms are considered based around a generic 40˚ edge-aligned configuration. The VLM predicts a linear variation of lift and pitching moment with incidence angle, and substantially under-predicts the induced drag. Results obtained from RANS and Euler agree well with experiment.


Schütte, A., D. Hummel, and S.M. Hitzel, Flow Physics Analyses of a Generic Unmanned Combat Aerial Vehicle Configuration. Journal of Aircraft, 2012. 49(6): p. 1638-1651. https://doi.org/10.2514/1.c031386

Bertin, J.J., Aerodynamics for Engineers. 4th ed. 2002, USA: Prentice Hall.

Gudmundsson, S., Chapter 9 - The Anatomy of the Wing, in General Aviation Aircraft Design, S. Gudmundsson, Editor. 2014, Butterworth-Heinemann: Boston. p. 299-399. https://doi.org/10.1016/b978-0-12-397308-5.00009-x

Frink, N.T., M. Tormalm, and S. Schmidt, Three Unstructured Computational Fluid Dynamics Studies on Generic Unmanned Combat Aerial Vehicle. Journal of Aircraft, 2012. 49(6): p. 1619-1637. https://doi.org/10.2514/1.c031383

Shevell, R.S., Fundamentals of Flight. 2nd ed. 1989, New Jersey: Prentice Hall.

Buchholz, M.D. and J. Tso, Lift Augmentation on Delta Wing with Leading-Edge Fences and Gurney Flap. Journal of Aircraft, 2000. 37(6): p. 1050-1057. https://doi.org/10.2514/2.2710

Anderson, D.F., Understanding flight. 2nd ed. ed, ed. S. Eberhardt. 2010, New York: New York : McGraw-Hill.

Kermode, A.C., Mechanics of flight. 12th ed / rev. by R.H. Barnard and D.R. Philpott. ed, ed. R.H. Barnard and D.R. Philpott. 2012, New York: Pearson Education.

Gudmundsson, S., Chapter 10 - The Anatomy of Lift Enhancement, in General Aviation Aircraft Design, S. Gudmundsson, Editor. 2014, Butterworth-Heinemann: Boston. p. 401-457. https://doi.org/10.1016/b978-0-12-397308-5.00010-6

Coppin, J., Aerodynamics, Stability and Shape Optimisation of Unmanned Combat Air Vehicles, in Department of Mechanical Engineering. 2014, University of Sheffield.

Robert, N., et al., Modification of the Flow Structure over a UAV Wing for Roll Control, in 45th AIAA Aerospace Sciences Meeting and Exhibit. 2007, American Institute of Aeronautics and Astronautics. https://doi.org/10.2514/6.2007-884

Anderson, J.D., Fundamentals of Aerodynamics. 2010, Boston: McGraw-Hill Education.

Wilson, H.A. and J.C. Lovell, Full-scale Investigation of the Maximum Lift and Flow Characteristics of an Airplane Having Approximately Triangular Plan Form. 1947.

Earnshaw, P.B., An experimental investigation of the structure of a leading-edge vortex, M.o. Aviation, Editor. 1961.

Polhamus, E.C., Predictions of vortex-lift characteristics based on a leading-edge suction analogy, in 6th Annual Meeting and Technical Display. 1969, American Institute of Aeronautics and Astronautics. https://doi.org/10.2514/6.1969-1133

Elkhoury, M. and D. Rockwell, Visualized Vortices on Unmanned Combat Air Vehicle Planform: Effect of Reynolds Number. Journal of Aircraft, 2004. 41(5): p. 1244-1247. https://doi.org/10.2514/1.6290

Kingsley, S. and S. Quegan, Understanding Radar Systems. 1992, Berkshire: Mcgraw-Hill.

Jenn, D.C., Radar and laser cross section engineering. 1995, Washington, DC: American Institute of Aeronautics and Astronautics.

Johnston, L.J., High-Lift Aerodynamics of Uninhabited Combat Air Vehicle Configurations with Reduced Radar Cross-Section Characteristics, in RAES Applied Aerodynamics Conference. July 2012: Bristol.

Gad-el-Hak, M., Flow Control: Passive, Active, and Reactive Flow Management. 2000, New York: Cambridge University Press. https://doi.org/10.1017/cbo9780511529535

Lachmann, G., Results of Experiments with Slotted Wings. 1924, NACA.

Johnson, R.W., The handbook of fluid dynamics. 1998, Heidelberg: Springer-Verlag.



How to Cite

Ali, U. and Chadwick, E. (2016) “Flow Control and High-Lift Performance for Flying-Wing Unmanned Combat Air Vehicle Configurations by inserting slots”, The International Journal of Multiphysics, 10(2), pp. 117-138. doi: 10.21152/1750-9548.10.2.117.