ESTIMATION OF STATIC AND DYNAMIC FLOATATION CHARACTERISTICS DURING AIRCRAFT DITCHING

Ditching performance is an essential part of civil aircraft certification procedures. However, there is little research on this area. This paper uses VB language to investigate and analyze floatation characteristics. After importing the simplified plane model the trapezoidal rule is used to complete the integral of the volume below the waterline, so as the principle of Archimedes to calculate the buoyancy and floating moment. Unlike the static floatation characteristics focusing on the problems of buoyancy and stability, an aircraft sinking posture is what the dynamic floatation characteristics research on. The sinking process is simplified as a quasi-static process. With time approaching gradually, the weight of water entering into the plane increases, and the sinking posture changes in three degrees of freedom. In wave environment, the strip method is used to add the disturbed flow resistance. This method keeps an inexpensive computational cost with the guarantee of calculation accuracy. In the end, this paper valuated the security in static floatation characteristics for a plane, within the permitted weight and the Center of gravity (C.G) configuration the static float attitude is obtained. Considering structure damage, the dynamic flooding process of the plane is simulated. The difference in dynamic sinking process between the calm surface and wave environment is also been analyzed.