Simulation Research On Maneuveration Mathematic Model Of Air Cushion Vehicle In Seas

The pilot training simulator of the air cushion vehicle is a kind of equipment to make pilots handthe operation skills faster and better，the using of simulator training is in good military effect andeconomic benefits for some expensive air cushion vehicle. Mathematical model of ship motionand equipment is one of the core technologies in the research and the development of pilottraining simulator. The main object of this paper is to establish motion and equipmentmathematic model which is applied for the pilot training simulator based on the theory of shipmotion and aerodynamics.In order to describe the maneuvering motion, in the coordinate motioned with body, the authorderived six-degree equations of motion both in still water and in windy environment according tothe theorem of movement of centroid and the theorem of moment of momentum about centroid.After equations was established, on the basis of approach given by Mathematical Model Group(MMG) in Japan, this paper separated the loads on the air cushion vehicle model into thehydrodynamic resistance force, the force generated by the equipment control, areoforce, waveresistance and restoring force. Hydrodynamic resistance includes cushion wave resistance andskirt resistance. On the foundation of empirical formulation before, the mathematic of variousresistance loads were given. Through considering the static blance equation, fan equation andflow contiuity equation, the calcation method of the pressure of the cushion was given.This paper, based on the mathematical model of six-degrees-of-freedom motion, develops amaneuverability-simulation program for an air cushion vehicle by the use of FORTRAN, in orderto verify the correctness of the model. With the use of this program, the maneuverableperformances of air cushion vehicle, when taking direct motion, turning around with regularrudder angle and revolution motion with regular pitch difference, are researched. The impact ofvarious factors, such as propeller rotation rate, initial speed, rudder angle and side driving gate,on the maneuverability are discussed. The particular characteristics, such as inward inclined andside drift, of air cushion vehicle are simulated. Moreover, comparisons among different rotatingmethod are made to analysis their advantages and disadvantages.Then, considering the loads coming from winds and waves on the foundation of model established before, the maneuverability of an air cushion vehicle within the environment of windsand waves is simulated. The performance of motion within winds and waves and the criticalcondition, under which the vehicle cannot rotate in the environment of following wind, areconcluded. Furthermore, the analysis of vertical-motion performance of air cushion vehiclewithin the environment of still water and wave water is made. Sink caused by cobblestone is alsosimulated. Based on the comparison between the results of this paper and pervious verified dates,the correctness of the mathematical model for the maneuverability is confirmed.