Transonic Numerical and Experimental Evaluation of Unconventional Lambda Wing Control Surfaces

Abstract

Lambda wing configurations are known to possess challenging flight characteristics at transonic Mach numbers. This study tests various methods for increasing the maneuverability and stability of the SACCON, a generic lambda wing configuration. Several control concepts are presented and tested to determine their effects on the lateral-directional and longitudinal stability of the aircraft. The first category of control concepts uses smooth surface deformations of the wing tips to eliminate control surface gaps found with traditional flap-based systems. The second category uses panel deflections on the upper surface of the aircraft. Each concept is simulated at Mach numbers in the range of 0.5≤M∞≤0.850.5≤M∞≤0.85 using the TAU code of the German Aerospace Center (DLR), with subsequent wind tunnel tests taking place in the Transonic Wind Tunnel of the German–Dutch Wind Tunnels (DNW-TWG) in Göttingen, Germany. The main flow features created by each control device and the Mach number effects are discussed, as are their effects on the aircraft’s aerodynamic performance. The smooth wing-tip deformations isolate the control derivatives and are best able to enhance lateral-directional stability. The upper surface devices create a more complicated response but offer more immediate application due to their reliance on firmly established technology.