Abstract:
Summary.--In this report the results are given of an investigation, without the application of suction, into the lift, drag and pitching moment of an aerofoil of 31.5 per cent thickness/chord ratio designed specifically for use with a single suction slot at 0.69c from the leading edge. The object of the tests was primarily the estimation of the behaviour of the wing at high Reynolds numbers in the event of the failure of the suction, but it was also hoped to obtain information concerning some reasonable method of countering any serious effects that might arise. Consequently, the tail of the aerofoil was hinged to form an unslotted main flap and fitted with a detachable split flap. Tests were also made with a slotted main flap. The Reynolds number range extended from 0.3 x 10(to the power of 6) to 7.3 x 10(to the power of 6). Critical regions were observed and the scale effects were found to be large. The influence of the flaps was generally more or less normal, although the increase in CL max. was less than half that for a conventional aerofoil of similar thickness/chord ratio, the NACA 0030. At R - 7.25 x 10(to the power of 6) without flaps, CL max. for the Glas II was 1.21 compared with 0.7 for the NACA 0030. A 15 per cent split flap at 90 deg on the latter increased CL max. to 2.2 whereas the values for the Glas If only reached 1.71 with a similar split flap and 1.64 with a main flap angle of 40 deg. The effect of the slot between the main flap and the forward portion of the wing was found to be comparatively small.
