The Air Drag of Hulls: The Effect of Alterations in the Main Dimensions and Various Detail Features

THE design of a flying boat hull is a compromise between the usually conflicting requirements of good performance on the water and in flight. For example, from aerodynamic considerations the hull should be without discontinuities, while for low water resistance when planing, discontinuities are necessary in the form of steps and chines, the former to localise the wetted area to that portion providing lift, and the latter to keep the spray as low as possible. Again, though the minimum air drag results from symmetry about the longitudinal axis, it is usual to curve the tail of a hull upwards to give the tail plane sufficient water clearance.