A Developed Theory of Spoilers on AerofoiIs

A theory for the lift and pitching moment coefficients due to two-dimensional normal spoilers only erofoile flow na8 developed from that of Woods. in incompressible By making use of experiments on a symmetrical aerofoll fitted with epoilere, the displacement thickness of the boundary layer at the spoiler position and a measure of the pressure in the separated region behind the spoiler were taken Into account. These empirical modificatione led to good agreement with experiment over a range of aerofoil incidence. Since a change of incidence is similar in many respects to a change of aerofoll shape it appeared likely that the modified theory would apply over a wide range of aerofoll aectlons. Further experiments upon an aerofoil of considerably different shape provided confirmation, good agreement being obtained between theory and experiment. A limited eerie8 of experiments was made on spoilers of finite epan upon the original aerofoil. For spoilers of epan greater than 80% of the aerofoil chord it was found that their lift and pitching moment increment8 could be correlated roughly with those due to two-dimeneional spoilera.