AFTER pointing out that the rivalry between the monoplane and the biplane is of long standing, and that each must therefore have some advantages, the author proceeds to the consideration of the question at issue by comparing structural efficiency, aerodynamic characteristics, performance, and certain other features. In structural efficiency the biplane is considered superior both in strength-weight ratio and in rigidity, but the monoplane has the advantage of being better adapted to metal construction. In aerodynamic characteristics the monoplane has the advantage on the basis of wings of the same area and profile, but the lower lift-drag ratio and greater unit weight of the monoplane wing tend to reduce its superiority. World's records in performance are divided between the two types, and in speed the recent Schneider Cup races show the monoplane and the biplane to be about equal.
The biplane has the advantage in affording better vision and in smaller size, but is likely to be more expensive, except that it can be built of wood, whereas the monoplane would have to be of metal. The author does not attempt to draw a conclusion as to the general superiority of either type, but believes that the decision in any individual case should rest on the circumstances of that case.