Wing mounting nacelle for a very high by-pass ratio turbojet aero-engine

Abstract

A nacelle for mounting under the wing of an aircraft a turbojet engine unit of the rear contrafan type with a very high by-pass ratio, the engine including a gas generator driving two overlapping contra-rotating turbines integral with ducted contra-rotating propellers downstream of the gas generator. The nacelle includes generally cylindrical inner and outer cowlings defining the secondary flow path containing the propellers, and a mast for suspending the engine unit comprising a pair of arms disposed in the longitudinal vetical axial plane of the engine unit and contained in a fairing, and a horizontal carrier beam fixed to the lower ends of the arms and disposed between the inner cowling and the engine casing. The upper ends of the arms are fixed to a box structure of the wing either directly or through a conventional engine pod suspension mast. In the former case the thickness of the outer cowling is integrated into the thickness of the wing, and the outer side of the cowling merges with the lower wing surface by means of a Karman type profile evolving in a direction from upstream to downstream in such a manner that, in an axial longitudinal plane vertically through the longitudinal axis of the engine unit, the generatrix defining the inner side of the outer cowling is overall tangential to the lower wing surface. The inner and outer cowlings are each divided into 120.degree. sectors, the lower two of which can be pivoted outwards and upwards to simplify maintenance.