Experimental simulation of maneuvers in a wind-tunnel

Abstract

In the process of aircraft development numerical approaches are gaining more and more importance. Not only steady flight conditions need to be modelled but also dynamic derivatives and last but not least realistic flight maneuvers. At DLR a numerical simulation framework is under development for calculating a freely flying maneuvering delta-wing aircraft. In order to obtain a data base for validating the simulation framework ground-based simulations of complex maneuvers of an aircraft have been performed in the open test section of the 2.85 X 3.20 m2 low-speed atmospheric wind tunnel NWB of the German-Dutch Wind Tunnels DNW. A fully equipped wind tunnel model of the X-31 was developed and built to a scale of about 1/7.25. The model is equipped with eight remotely controlled flaps that are moved by eight servo motors. Dynamic surface pressures have been measured by miniature piezo-resistive pressure sensors located at 60% and 70% chord length on the upper surface of the delta wing and on the leading edge flaps. Forces and moments were obtained by a 6-component strain gauge also included in the main part of the model. In the wind tunnel a newly installed novel test rig with six degree of freedoms was used for the first time for moving the model. The complex three-dimensional motion of the model is controlled by an optical position tracking system. In addition to pitching, rolling and yawing motions also real flight maneuvers, for example corresponding with steady-heading sideslip test points, were simulated. Both, the specific technical equipment of the model and the novel six DOF test rig will be reviewed. Thereafter, experimental results obtained will be discussed and compared with numerical results.