Joined Wing Configuration for High Speeds - A First Stage Aerodynamic Study

Abstract

Joined Wing Configurations have been proposed for Unmanned Sensor Craft air vehicles as the air-breathing component of a future intelligence, surveillance, and reconnaissance (ISR) infrastructure to provide revolutionary capabilities. In this role the Sensor Craft is required to house a large diamond shaped antennae within the wing planform. The high aspect ratio (AR) wings offer aerodynamic efficiency. Very large fuel capacities are required to enable the Sensor Craft to loiter at high altitude for a few days in each flight. This implies that a wide CL–altitude capability is required. Several types of high AR joined-wing aircraft configurations can be envisaged to meet the possible flight envelope. Previous studies have considered various joined-wing planforms (constant chord on front, rear and tip wings, increased root chord on front and rear wings and front wing with Lambda planform). Each case was designed for cruise at Mach 0.6 with aftand forwardswept tips using conventional thick super-critical aerofoil sections and laminar flow sections. The relatively clean lines of the planforms showed the potential for further development at higher speeds, Mach 0.8. With a transonic capability, the configurations can be adapted into the Unmanned Combat Air Vehicle (UCAV) role. The Lambda Joined-Wing planform was selected for this design study as it offered greater structural integrity. The implications of typical flight envelopes on wing design aspects have been mentioned. The results of Lift and Drag estimation studies have been presented. These have enabled an assessment of performance and endurance for the UCAV configuration. Further work is proposed in several areas.