Drag Polar for Combat Aircraft

For combat aircraft design, the drag estimation plays a vital role for having better flight performance with less fuel consumption. The drag reduction has become a prime importance to military and civilian aircraft, because for an increase of one Count (i. e.,
CD=0.0001) necessitate for 80 kg reduction in weight for attaining the same performance. Therefore to persists a better performance of combat aircraft it is required an accurate prediction of drag at subsonic and supersonic speed. In supersonic speed, the drag becomes more essential due to shock wave formations which causes a wave drag. Computational Fluid Dynamics (CFD) techniques have been improved over the last decade for an accurate prediction of the drag at subsonic to supersonic speeds. The evaluation of drag assists in improving the aircraft design and performance. In this study, drag polar on combat aircraft with clean and stores configuration has been assessed for drag estimation. Initially, the study has been carried on body of revolution (BOR) to quantify the wave drag contribution between aircraft clean and stores configuration. Hence, BOR provides a rough estimation of drag for a given aircraft area-distribution in minimum turn-around time, as a consequence improving the aircraft design and performance through Aera-distribution. Moreover, the N-S simulation has been studied on 3D aircraft for drag polar from subsonic to supersonic speed. Results were shown that the estimated wave drag through BOR has shown similar to 3D Navier Stokes (NS) aircraft simulation. Further, the drag estimated at subsonic and supersonic regimes for clean and store configuration has shown that the drag was predominant at supersonic regimes due to the cause of wave drag than at subsonic regimes. Therefore minimizing the wave drag play an essential for combat aircraft performance. Several analytical [1, 2], experimental [3, 4] and numerical [5, 6] studies were made related to aerodynamic characteristics of fighter aircrafts for supersonic, transonic or subsonic regimes.