Investigation of factors affecting the sticking of insects on aircraft wing surfaces

Abstract

This aircraft industry is concerned with the increase of drag on planes due to the sticking of insects on critical airfoil areas. The objectives of the present study were to investigate the effects of surface energy and elasticity on the number of insects sticking onto the polymer coatings on a modified aircraft wing and to determine the mechanism by which insects stick onto surfaces during a high-Velocity impact. Analyses including scanning electron microscopy (SEM), electron spectroscopy for chemical analysis (ESCA) and contact angle measurements of uncoated and polymer-coated aluminum surfaces have been performed. An air-gun was designed to accelerate insects to high speeds and impact them onto modified wing surfaces in a laboratory environment.

A direct relation between the number of insects sticking on a sample and its surface energy was obtained. Since the sticky liquid from a burst-open insect will not spread on the low energy surface, it will ball up providing poor adhesion between the insect debris and the surface. The incoming air How can easily blow oH' the insect debris thus reducing the number of insects that remain stuck on the surface. Also a direct relation between the number of insect sticking onto sample surfaces and their moduli of elasticity was obtained. The deceleration of an insect impacting onto an elastomer reduces in proportional to the modulus of elasticity of the material. As a consequence, the rate of change of momentum is lower and the force and pressure exerted on the body of the insect is reduced if it impacts onto a material with a low modulus of elasticity. This lessens the chance of bursting the i insect exoskeleton.