THE WIDGEON AND PORPOISING

摘要

Porpoising in hull seaplanes can be explained by a graph that shows the range of stable pitch attitudes at different waterspeeds. The hull will porpoise if you raise the pitch above an upper stability limit, or if you let it fall below a lower limit. The accompanying graph shows the basic shape of these upper and lower stability limits for the sake of illustration, but the exact details of the curves vary depending on the particular airplane and on various conditions including weight, flap setting and water surface to name a few. Some airplanes have a wide window of stability and mild porpoising tendencies. The Widgeon has a narrow window and a mean porpoising tendency, which makes this an important topic.