Non Linear Induced Drag Study of Generically Cambered Closely Coupled Dual Wings

A non-linear thin vortex lattice method, BSAERO, with wake rollup has been used to analyze closely coupled generic dual wings. These induced drag studies involved using generic mean camber line wings created using two parabolas. Using this parabola method the location of maximum camber and the magnitude of the maximum camber were varied independently of one another. C_L/C_Di was used as the success parameter for a particular wing system configuration. The best dual wing geometry configuration had a C_L/C_Di 18% greater than the comparable dual baseline with symmetric wings. The worst dual wing configuration had a C_L/C_Di which was 63% below the dual wing baseline. Systematic result are presented which will demonstrate trends as well as magnitudes for the best types of dual wing configurations for minimum induced drag. Contrary to single wing results in which essentially the same C_L/C_Di results were found with or without wake rollup these dual wing results under certain wing geometries yield significantly different C_L/C_Di results with and without wake rollup. The differences with this parameter for a flat wake versus a rolled up wake varied from 0.5% to 48% with an average of 7.2%. These differences are discussed in detail.