The objective of this research is to implement and validate a method to compute the induced drag of multiple lifting surfaces aircraft configurations. The lifting line theory serves as a fundamental basis to calculate the induced drag. It was used by Laurendeau to develop a methodology to solve for the minimum induced drag lift distribution of three lifting surfaces aircrafts; equations that were used as a starting point for this work. Implementation is made such that non-planar wing and user-defined spanload distributions could be analyzed. A curve-fitting methodology is developed to adapt mathematics to the input spanload distribution, and a correction is applied to the induced drag results so that the lift over the fuselage is taken into account. Minimum induced drag lift distribution is also obtained as per Laurendeau’s methodology. Results for wing-body-winglet configurations show good concordance with computational fluid dynamics (CFD) with a precision of more or less two drag counts. This shows that a lifting line approach, once corrected for the fuselage effect and dihedral, can provide accurate induced drag results. However, due to the absence of proper comparative data for two and three lifting surfaces aircraft configurations, an in-depth validation remains to be done for such aircraft designs. To do so, an approach to obtain the Oswald efficiency factor from Euler CFD results is proposed.

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Implementation and validation of a method for computing the induced drag of multiple lifting surfaces aircrafts

Comparison of Vortex Lattice and Prandtl-Munk Results for Optimized Three-Surface Aircraft

The experimental procedure and aerodynamic force and moment measurements for wind tunnel testing of the three lifting surface configuration (TLC) are described. The influence of nonelliptical lift distributions on lift, drag, and static longitudinal stability are examined; graphs of the lift coefficient versus angle of attack, the pitching moment coefficient, drag coefficient, and lift to drag ratio versus lift coefficient are provided. The TLC data are compared with the conventional tail-aft configuration and the canard-wing configuration; it is concluded that the TLC has better lift and high-lift drag characteristics, lift to drag ratio, and zero-lift moments than the other two configurations. The effects of variations in forward and tail wind incidence angles, gap, stagger, and forward wind span on the drag, lift, longitudinal stability, and zero-lift moments of the configuration are studied.

C. Ostowari

Papers

An experimental study of the lift, drag and static longitudinal stability for a three lifting surface configuration