Wing Baffles.
An attempt to prevent air leakage caused by this is occasionally observed in the employment of vertical vanes, or wing baffles. In the case of a machine with the lower plane abutting against the side of the fuselage, these would not be necessary, the fuselage acting in the same manner. The baffles are usually of three-ply or spruce, and shaped to project above the top and bottom surfaces, this projection rarely exceeding six inches. A typical arrangement is illustrated by [Fig. 41], which also shows the exposed spars streamlined with a fairing of three-ply. It is typical of the varied opinions which still exist, that on some machines the wing roots are merely washed out somewhat abruptly. If this air leakage is of any moment, it is apparent that it must detrimentally affect the lift-drift ratio. As a proof of the existence of pressure at the openings in the wing, the writer remembers the case of a well-known seaplane, where the wing baffles on the centre section were made of somewhat thin three-ply. In flight it was noticed by the pilot that these were being forced away from the wing, and subsequently these were replaced by baffles of stouter construction.
Fig. 41.—Wing baffle.