Patent ID: 8870120

Claim:
An aerofoil comprising a pair of skins which form low pressure and high pressure surfaces of the aerofoil; and a pair of spars which join the skins, wherein one of the skins and at least one of the spars are formed by a composite structure comprising a first section; a second section; and a curved corner joining the first section to the second section, the structure comprising a stack of fibre-reinforced plies, the stack including: a. a first external ply which runs from the first section into the second section round an inside of the corner; b. a second external ply which runs from the first section into the second section round an outside of the corner; c. a discontinuous first internal ply which is sandwiched between the first and second external plies and is dropped off inside the structure so that more of the first internal ply is located within one section than within the other section; and d. a second internal ply which is sandwiched between the first and second external plies, wherein at least part of the first and second internal plies are both located within the same section, the fibres of the first internal ply run at an angle θ to the fibres of the second internal ply in the section where they are both located, and the angle θ is greater than 3° but less than 20°.