Analysıs of a Bırd Strıke on the External Fuel Tank of a Jet Traıner Aırcraft

Abstract

Bird strike is defined as a collision between a bird and an air vehicle during flight, take-off of landing. According to statistics, a bird strike occurs once every 2000 flights. [1]

A collision with a bird during flight can cause serious damage on aircraft. All forward facing components shall be taken into account i.e. the engine fan blades, inlet, windshield, canopy, radome, forward fuselage skin and the leading edges of wing and empennage. The Aviation authorities require that the bird strike resistance of these components should be proved by certification tests.

The aviation authorities regulations for forward facing components are mainly listed below. • For windshield and canopy, 4 lb bird impact resistance is required at cruise speed without penetration. • For wing leading edges, 4 lb bird impact resistance is required at operational speed. • For empennage leading edges, 8 lb bird impact resistance is required at operational speed. • For engine and inlet, 4 lb bird impact resistance is required.

The aim of this study is to analyze the effect of bird strike on an external fuel tank of a jet trainer aircraft and contribute an example study to the literature of our country. After theoretical method was mentioned, information was given about numerical methods and compared with each other. After that, a geometry, dimensions and density of bird was defined and analyses were done using cylindrical with hemisperical ends bird geometry using SPH method according to speed and mass given in literature.

The bird strike analysis performed for an external fuel tank of a jet-trainer aircraft. Fuel carrying capacity of the external fuel tank is 1000lb. The cross-section is elliptical. The analysis was carried out using two materials which are Aluminium 2024-T3 and Aluminium 7075-T6. The numerical analysis was carried-out using LS-DYNA program to analyse a 4 lb bird strike. The geometrical model of the impactor is 4lb and the density is 950kg/m³. For numerical simulation, the structure was modelled as a shell element by using hypermesh software and the bird was be modelled using SPH method. Using numerical analysis, the stress and displacement distributions, maximum stress and displacement were calculated. As a result, the robustness of the external fuel tank under bird strike was verified.