Abstract:
Under static conditions or at low rates of advance, the blades of a single airscrew are often stalled, except perhaps for the outer sections. At first sight, it would appear that the same conditions must apply to the blades of a contra-rotating pair of screws. However, some measurements made in America have shown that the static thrust of contra-rotating screws is considerably greater than that of a corresponding single screw; and the same conclusion has been inferred from the short take-off run of a particular aeroplane with contra-rotating screws.
