Research On Major Safety Influence Factors Of Steam Catapult Launch For Carrier-based Aircraft

As the main equipment for carrier-based aircraft takeoff from aircraft carrier,steam-powered catapult improved takeoff efficiency,and guaranteed the safety of man and aircraft.Therefore,it is very important to study the technology of catapult launch for carrier-based aircraft.The catapult process of carrier-based aircraft request the high performance of wet steam accumulator,launch bar,nose gear and carrier-based aircraft,so the catapult launch security issues is particularly important.In this paper,the major safety influence factors of steam catapult launch for carrier-based aircraft are going to be analysized and studied.The following contents are researched:Firstly,this article built a mathematical model of catapult launch,which comprised a thermodynamics model of steam-powered catapult,mathematical model of traction release device and a staged mathematical model of catapult launch for aircraft based on actual catapult launch operation for carrier-based aircraft.First the thermodynamics model of steam-powered catapult was validated by three kinds of test data:(1)the curve of accumulator pressure was compared with experimental data;(2)the curve of accumulator pressure was compared with experimental data;(3)the curve of deadload acceleration was compared with experimental data.And then the mathematical model of catapult launch for aircraft was validated by three aspect:(1)the theoretical derivation of the equation of the minimum release load of holdback bar was carried out,and compared with the formula in the military specification;(2)the curve of accumulator pressure and cylinder pressure were compared with experimental data;(3)the variation of catapult tow force with stroke was compared with the test data in the military specification.Secondly,the simulation system platform of steam catapult launch for carrier-based aircraft was developed,and the analysis of simulation results of steam catapult launch system was carried out.The safety boundary building principle of steam catapult launch was proposed,on this basis,the safety boundary of aircraft,wet steam accumulator,launch and nose gear were analyzed.It made better basics to study the safety boundary study of steam catapult launch for aircraft in the latter chapters.Thirdly,conducting the research of parameters optimization for wet steam accumulator based on genetic algorithm and safety criterions of catapult launch.The optimal parameters of wet steam accumulator were obtained.On this basis,the safety boundary of steam pressure and liquid level height were obtained through a lot of simulation test loop iteration.Thendetermine the safety boundary of wet steam accumulator which meet the constraints of safety criterions of catapult launch,and the safety envelope of wet steam accumulator were obtained.Then the safety criterions of wet steam accumulator for steam catapult launch were established.Then,this article built a launch bar dynamics model after the launch bar automatically disengages based on actual catapult launch operation for carrier-based aircraft.On this basis,the effect of a number of factors on catapult launch safety for carrier-based aircraft with the launch bar were analyzed.And then the research of safety boundary of launch bar was carried out by three groups of catapult launch simulation experiment.Finally the research of safety boundary of buffer initial pressure and elastic support mass for nose gear was carried out.The study result can give some theoretical reference value to the design and test of launch bar,nose gear and make of safety criterion of launch bar,nose gear.Finally,a staged mathematical model of off-center catapult launch were developed for the whole catapult process based on actual off-center catapult launch operation for carrier-based aircraft.The effect of off-center catapult launch on carrier-based aircraft,steam-powered catapult and launch bar were studied,and some key parameters were compared and analyzed about on-center and off-center catapult launch.The study result can give some reference value to formulation of safety criterion of off-center catapult launch for carrier-based aircraft.