EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF UNSTEADY AERODYNAMIC DERIVATIVES FOR A GENERIC LAMBDA WING UCAV CONFIGURATION

Abstract

Experimental and numerical investigations have been conducted in order to analyze the unsteady aerodynamic and flight mechanical behavior of a 53° flying wing configuration representing a generic unmanned combat air vehicle (UCAV). The considered vehicle is named SACCON/ DLR-F17 and the here presented results have been collected within an internal project of the German Aerospace Center in collaboration with the NATO Task Group AVT-201 on “Extended Assessment of Reliable Stability & Control Prediction Methods for NATO Air Vehicles”. Both projects have the aim to conduct studies of an integrated approach to predict the stability and control characteristics for a generic UCAV configuration based on both, experimental and numerical investigations. Systematic investigations have been performed to determine the dynamic derivatives for the longitudinal and lateral motion. A comparison between data of experimental wind tunnel investigations and numerical simulations under real flight conditions is given. In wind tunnel tests, performed in the DNWNWB wind tunnel, the SACCON configuration was studied at a reduced scale of 1:8 and a Mach number of M∞ = 0.15. Forced oscillation motions were performed during these tests to calculate the dynamic derivatives from force and moment data. For the numerical calculations the same reduced frequencies were applied with the full scale configuration under real flight conditions using the RANS method DLR-TAU. The planform aerodynamics is governed by complex nonlinear flow phenomena due to leading edge vortex flow separation at moderate to high angles of attack. Based on the numerical results an interpretation of the complex vortex flow is given in order to understand the unsteady flow phenomena for a variety of roll, pitch, and yawing motions.