Porpoising instability study of the floatplane during take off operation on calm water

Abstract

Floatplane is a type of airplane that can take-off and land on the surface of the water, for that it is equipped with a float that is installed under the fuselage to serve the buoyancy force. An important phenomenon that often occurs and should be avoided during a take-off operation is porpoising because it causes longitudinal instability of the float which has an impact on passenger safety and comfort. This paper describes the porpoising mechanism and the variables that can influence the occurrence of this phenomenon. The most dominant variables include the location of the longitudinal center of gravity (LCG) and the deadrise angle which are optimized by considering the take-off speed. A numerical arrangement based on computational fluid dynamics (CFD) techniques is proposed to simulate a three-dimensional fluid flow around a free-floating float in calm water. The accuracy of the simulation results shows a good fit compared to the previously published experimental and numerical results.