An aerofoil designed to give laminar flow over the whole surface with boundary-layer suction

Abstract

A new type of aerofoil is described over the whole of which it is possible to maintain laminar flow by means of a small amount of boundary-layer suction. Preliminary small scale experiments at Reynolds numbers of about 0.37 × 10power6 show that the mass flow it is necessary to remove by suction is less than that in the laminar boundary layer at the slot. On the basis of these small-scale experiments the effective drag of this aerofoil at a Reynolds number R is estimated to be approximately 6.0Rpower-1/2. Thus at the Reynolds numbers reached in present day flight (say 25 × 10power6) an effective drag coefficient of 0.0012 may be expected. These figures are all subject to experimental confirmation at higher Reynolds numbers. More elaborate tests are to be made in the National Physical Laboratory 13 ft. × 9 ft. wind tunnel at Reynolds numbers up to 5 × 10power6. Other experiments are also planned in the N.P L. Rectangular High-Speed Tunnel.