Ice and contamination protection for laminar flow porous structure

A nacelle (20)(figure1) having a porous structure is provided with laminar flow control and contamination protection. In region B suction through a composite layer 24 is achieved by evacuating a chamber 30 adjacent the inner surface 26 of the nacelle (20) to provide laminar flow control. At the leading edge 22 of the nacelle (20) a permeable sintered metal sheet 32 is attached to an inner surface 26 of the composite layer 24 to control the flow of a contamination protection liquid over the leading edge 22 of the nacelle (20). The liquid is contained in a chamber 36 adjacent the sintered metal sheet 32 which is defined by a backing sheet 34 which has a series of depressions 35 therein. Hot air fed through a perforated pipe 38, impinges upon the backing sheet 34 and the depressions 35 transmit heat to the sintered metal sheet 32. The sintered metal sheet 32 has good thermal conductivity and in turn heats the porous composite layer 24 to prevent the formation of ice thereon.