Wingtip devices are used to improve the efficiency of the fixed wing aircraft by reducing the total drag which may lead to reduction in coefficient of lift. The winglet partially acts like an end plate to the aircraft wing. This device reduces the pressure nullification at the wingtips to a large extent and diminishes the adverse effect of the wingtip vortices. Thereby, it results in the reduction of induced drag. Aerodynamic efficiency is an important factor in commercial aircrafts wherein induced drag plays a major role. The strength of wingtip vortices is inversely proportional to wingspan and speed of the plane. So aircraft with large wingspan and high speed will have high wingtip vortices. Thus, the vortices will be maximum during takeoff, climb and landing. Changing the design of the lift producing devices will make changes in the strength of the aircraft. Winglets are extensions at the tip of the wing which reduces the vortex formation. Many types of winglets are available to serve different purposes. The primary focus of this paper is to investigate the effect on coefficient of lift using fixed to flexible winglets. A model was fabricated and tested in low speed wind tunnel for different inlet conditions and angle of attack, the coefficient of lift for each winglet is compared.

coefficient of lift, fixed winglet, multi-degree winglet, wingtip vortices.