Further Discussion of Bird Strike Design Issues for Engines with Obscured Fans

A previous conference presentation (Baltimore, 2004) introduced the subject of obscured turbo-fans and discussed it in the context of bird strikes. In such a case, the bird will have significant interaction with the internal structure of the aircraft intake during its passage from intake lip to fan and damage to the bird may well occur causing it to pose a significantly different threat to the integrity of the engine. This paper explores the possible interactions that take place in such an installation prior to the bird reaching the fan face and makes use of engine and bird structural test data to describe the effect of such interactions on the bird structure. The implications of these interactions on the behaviour of the fan during the bird ingestion are then explored; again using test and analytical evidence.