Aircraft fuel tank

An aircraft wing fuel tank 16 comprises tank walls enclosing a liquid storage space 14. A first tank wall 10 is formed by an external skin of the aircraft, coupled to and oblique to a second tank wall 8 (rib or spar of an aircraft substructure), which are made of carbon fibre composite (CFC). A (preferably aluminium) metal or alloy reinforcing member 18 is fixedly attached to the first and second tank walls. The reinforcing member comprises a first portion 18a connected to and oblique to a second portion 18b. The first portion is attached to the first tank wall and the second portion is attached to the second tank wall. The reinforcing member may be L-shaped (having perpendicular first and second portions), and the second tank wall may be L-, J-, or C-shaped. When attached together they may form T-, I-, or J-shaped assemblies respectively. The assembly may reduce hydrodynamic ram pressure generated on impact with a high speed projectile 24 and prevent the skin from delaminating.