Prediction of Aerodynamic Loads on Close-Coupled Canard Configurations - Theory and Experiment.

Abstract : The close-coupled canard configuration has emerged as an advanced design for highly-maneuverable fighter aircraft, achieving much of its lift at high angles of attack from vortex lift. This paper summarizes the progress to data on a comprehensive investigation to develop a simplified theory for the aerodynamic performance. Flow visualization tests on a 6 ft (1.83 m) semi-span model of a representative configuration are first discussed. These tests are followed by measurements on a 12 ft (3.66 m) full-span model to obtain force and moment data, as well as pressure data on the upper surface of the wing. With this understanding, the proper velocity/vorticity relationships on the wing and the burst vortex above the wing are found and a compatible mathematical model is formulated. The general solution to the potential flow problem is then given and the influence of conical parts of the burst vortex system is derived. Numerical results for these steps look very good. In conclusion, the final steps in the development of the theory are outlined and a new mechanism for the vortex lift is identified. (Author)