50. Sir F. HALLasked the Secretary of State for Air whether official experiments have been made to test the efficacy of the slot and aileron system of safety control for aeroplanes; what has been the conclusion come to as the result of such experiments; and how many machines in the Royal Air Force are now fitted with this device?
§ Sir P. SASSOONThe combined slot and aileron device originated in the National Physical Laboratory and has been developed under the guidance of the Aeronautical Research Committee. Up to the present it has been experimentally applied to five types of service aircraft and development is in progress. The device shows great promise in certain directions but its mechanical application presents considerable difficulties and up till now none of the different mechanisms by which it has been applied can be considered satisfactory for Service use. The latest form which has been tried is more promising than any hitherto employed and it is hoped that it will, after further trial, be found satisfactory. Pending the elaboration of a satisfactory mechanism it has not been possible to fit this device to any but the experimental machines above referred to.