Control of Tailless Aircraft

This paper presents the details about lateral-directional and longitudinal control of a tailless aircraft for landing condition. Tailless aircraft configurations are specifically designed for stealth and the absence of a vertical fin aids in low visibility to RADAR. For such configurations, yaw control becomes a major challenge. Usage of control surfaces, known as spoilers, specifically to obtain yaw-controllability is one of the approaches. For the considered tailless aircraft configuration, it was observed that due to deflection of spoilers, the effectiveness of elevons was significantly hampered. This decrease in effectiveness demands higher deflection of elevons which is not preferred due to actuator requirements. Another approach to tackle the yaw-controllability would be to use the existing elevons present in aircraft. This approach is discussed and analyzed in this paper. Critical landing condition have been chosen as the design point to cater for, namely: (a) to generate sufficient yawing, rolling and pitching moments to restore the aircraft (b) by using minimum deflection angles to control (c) to attain required CL at landing condition. Few results of this study are presented here.