Aerodynamic Performance of Lambda Wing-UCAV at Different Back-sweep Angles

Document Type : Regular Article


NMICPS Technology Innovation Hub on Autonomous Navigation, Indian Institute of Technology, Hyderabad, India



Unmanned Combat Aerial Vehicles (UCAVs) are designed to be lightweight and compact, which can impact their overall lift and aerodynamic capabilities. This study focuses on enhancing the Coefficient of Lift (CL) by optimising the Back Sweep Angle in the Lambda wing-UCAV. The model's baseline geometry remains unchanged during the experimental and numerical analysis, while different back sweep angles ranging from δ=00 to δ=500 are investigated at varied free-stream velocities and angles of attack. This helps to understand the generation of induced lift in the intricate shapes of the Lambda Wing. The results indicate a 5% to 10% increase in the lift for every 100 increments of the Back Sweep Angle, and the vortices' strength increases and reaches a maximum at δ=400. At greater angles (δ >400), the lift drops gradually with the Reynolds number. The stagnation point shifts from 25% to 35% along the chord towards the pressure surface as the angles of attack increase from α=50 to α=100. The angle of attack α>100.


Main Subjects

Aelaei, M., Karimian, S., & Ommi, F. (2019). Sensitivity analysis and optimization of delta wing design parameters using CFD-Based response surface method. Journal of Applied Fluid Mechanics, 12(6), 1885–1903.
Al-Garni, A. Z., Saeed, F., & Al-Garni, A. M. (2008). Experimental and numerical investigation of 65 degree delta and 65/40 degree double-delta wings. Journal of Aircraft, 45(1), 71–76.
Chaplin, R., & Birch, T. (2012, June 25). The aero-acoustic environment within the weapons bay of a generic UCAV. 30th AIAA Applied Aerodynamics Conference.
Coppin, J., Birch, T., Kennett, D., Hoholis, G., & Badcock, K. (2018). Prediction of control effectiveness for a highly swept unmanned air vehicle configuration. Journal of Aircraft, 55(2), 534–548.
Cummings, R. M., & Schütte, A. (2012). Integrated computational/experimental approach to unmanned combat air vehicle stability and control estimation. Journal of Aircraft, 49(6), 1542–1557.
Cummings, R. M., Liersch, C., & Schuette, A. (2018). Multi-Disciplinary design and performance assessment of effective, agile NATO air vehicles. 2018 Applied Aerodynamics Conference.
Frink, N. T., Tormalm, M., & Schmidt, S. (2012). Three unstructured computational fluid dynamics studies on generic unmanned combat aerial vehicle. Journal of Aircraft, 49(6), 1619–1637.
Lakshmanan, D., Boopathi, R., & Saravanan, P. (2023). Aerodynamic investigation and simulation studies on wing section of an unmanned aerial vehicle attached with solar plate. Journal of Applied Fluid Mechanics16(8), 1666-1674.
Nagel, A., Levy, D. E., & Shepshelovich, M. (2006, January 9). Conceptual aerodynamic evaluation of Mini/Micro uav. 44th AIAA Aerospace Sciences Meeting and Exhibit.
Peng, X., Kou, J., & Zhang, W. (2023). Multi-fidelity nonlinear unsteady aerodynamic modeling and uncertainty estimation based on Hierarchical Kriging. Applied Mathematical Modelling, 122, 1–21.
Petterson, K. (2006, January 9). CFD Analysis of the Low-Speed Aerodynamic Characteristics of a UCAV. 44th AIAA Aerospace Sciences Meeting and Exhibit.
Schütte, A., Huber, K. C., Frink, N. T., & Boelens, O. J. (2018, March). Stability and control investigations of generic 53 degree swept wing with control surfaces. Journal of Aircraft, 55(2), 502–533.
Sukruthi, C., Ashika, & Shali, S. (2021). Analysis of subsonic flow over delta winged aircraft. Seventh International Symposium on Negative Ions, Beams and Sources (Nibs 2020).
Syam Narayanan, S., & Asad Ahmed, R. (2021). Effect of fluid-structure interaction on noise generation in MAV with fixed and flapping membrane wing. Journal of Applied Fluid Mechanics, 14(6), 1817-1826.
Syam Narayanan, S., & Asad Ahmed R. (2022). Effect of chord-wise flexibility in the lift generation of flapping MAV with membrane wing. Aircraft Engineering and Aerospace Technology, 94(5), 792–798.
Van Rooij, M., & Cummings, R. M. (2018, June 24). Aerodynamic design of an unmanned combat air vehicle in a collaborative framework. 2018 Applied Aerodynamics Conference.
Younis, Y., Bibi, A., Haque, A. U., & Khushnood, S. (2012). Vortical flow topology on windward and leeward side of delta wing at supersonic speed. Journal of Applied Fluid Mechanics2(2), 13-21.
Zimper, D., & Hummel, D. (2018). Analysis of the transonic flow around a unmanned combat aerial vehicle configuration. Journal of Aircraft, 55(2), 571–586.