Month in the Patent Office

In a boundary layer control system for applying different degrees of suction to openings 11, 12, 13, 14 at different spanwise locations along a wing, the respective suction openings are connected by pipes 61, 62, 63, 64 to the first four stages of an air compressor 27 through annular compartments 47, 48, 49, 50 of increasing diameter. The compartments are formed with inlet guide vanes 35, 39, 41, 32, together with supporting struts 43, 44, 45, 46. As shown the compressor 27 is coupled to a turbine 29 driven by the exhaust gases from a main engine 72, the inlet pipe 76 having a control valve 78 connected to a lever 79 operating a mechanism for controlling a variable‐area jet nozzle 79a, so that the area of the nozzle opening is automatically reduced when the exhaust is bled off to the turbine 29. If the number of suction openings is greater than the number of compressor stages, more than one opening may be connected to some of the stage inlets, throttling devices being fitted in some of the connexions if required.