Tail and control surface sizing for UAVs

Abstract

Interest in the design and development of unmanned aerial vehicles (UAVs) has increased in the past two decades, due to the versatility of this type of aircraft. Missions of surveillance, detection of fire and biological, chemical and nuclear materials are ideal to be performed by a UAV remotely piloted or autonomous. This type of aircraft is included in a Reynolds regime still not well known and of recent studies. The low Reynolds aerodynamics has particularities that make the design of UAVs slightly different from the design of a common aircraft. The presence of separation bubbles, the position of the transition to turbulent flow, the hysteresis on the aerodynamic curves and the non-linearities on the lift curves show how different can be a UAV designed based on present methods. Due to technological advance in eletronics, like very small sensors and video cameras, smaller aircraft could be used, the micro-air vehicles (MAVs), inserting future designs in a more critical Reynolds regime. This work studies the eficiency loss of the aerodynamics caracteristics due to low Reynolds and separation bubbles, based on wind tunnel tests data of an airfoil with a plain flap. The results can be used as a modification of present design methods, focusing in empennages and control-surfaces sizing of aircrafts that are included in a Reynolds number ranging from 5·104 to 2·105.