A Comparative Study of the Low Speed Performance of Two Fixed Planforms versus a Variable Geometry Planform for a Supersonic Business Jet

Abstract

A numerical investigation of the effects of high lift devices on the low-speed performance of a generic swept wing and a delta wing was conducted. The two fixed planforms were initially sized to achieve the same high speed performance as the baseline variable geometry wing. Following a review of high lift devices a detailed analysis of their use was conducted with the aid of vortex lattice method and empirical formulations. The slat and Fowler flap combination proved to be the best mechanical solution. In comparison with the initially sized delta planform, the final delta planform required a 26% increase in wing area with high lift devices to achieve the required low speed performance. This increase in area resulted in a 14% reduction of the maximum lift-to-drag ratio at cruise. The fixed swept wing had an increase in area of 8% over the initially sized fixed swept planform. This resulted in a decrease of the maximum lift-to-drag ratio by 1.1% at cruise. The calculated specific air range ratio for the delta planform versus the variable geometry planform was 0.95. The calculated specific air range ratio for the fixed swept planform versus the variable geometry planform was 0.94. The resulting weight penalty for the variable geometry planform did not appear to be as detrimental as initially thought when comparing against larger fixed wing planforms with high lift devices. Leading edge extensions and vortex lift could provide an even further increase in �����