A Strategy to Design Bird-proof Spinners

Birdstrike is a serious threat for flight safety which causes every year remarkable losses. Even if modern aircrafts are certified for a level of bird impact resistance, it may happen that structures designed to carry aerodynamic loads, like a propeller spinner, may collapse after a bird strike. In general, the collapse of the spinner is not a concern if the fly-home capability is not compromised. In this paper, a strategy to design bird-proof spinner is introduced and its effectiveness evaluated by means of LS-Dyna. A SPH model of the bird was initially developed and validated. Then the impact of the bird onto a composite spinners was investigated. In particular, to capture its complex failure mechanism, the dynamic behaviour of the composite material used in the aircraft constructions was validated against specific dynamic tests. The influence of the spinner motion was also investigated and the differences between motionless and revolving spinners were pointed out. Improvements to the design of the reference spinner based on the idea of deflecting-the-bird instead of bagging-the-bird were developed and their performances numerically evaluated. In view of the results obtained, it was concluded that composite material and rotational motion can be exploited to design bird-proof spinner. Furthermore, it was observed that increasing the thickness of a spinner is not only against the weight constraints typical of aircraft constructions, but it is also ineffective.