title: Research on the water-entry attitude of a submersible aircraft.
abstract: BACKGROUND
  The water entry of a submersible aircraft, which is transient, highly coupled, and nonlinear, is complicated. After analyzing the mechanics of this process, the change rate of every variable is considered. A dynamic model is build and employed to study vehicle attitude and overturn phenomenon during water entry. Experiments are carried out and a method to organize experiment data is proposed. The accuracy of the method is confirmed by comparing the results of simulation of dynamic model and experiment under the same condition.
  
  
  RESULTS
  Based on the analysis of the experiment and simulation, the initial attack angle and angular velocity largely influence the water entry of vehicle. Simulations of water entry with different initial and angular velocities are completed, followed by an analysis, and the motion law of vehicle is obtained. To solve the problem of vehicle stability and control during water entry, an approach is proposed by which the vehicle sails with a zero attack angle after entering water by controlling the initial angular velocity. With the dynamic model and optimization research algorithm, calculation is performed, and the optimal initial angular velocity of water-entry is obtained.
  
  
  CONCLUSIONS
  The outcome of simulations confirms that the effectiveness of the propose approach by which the initial water-entry angular velocity is controlled.
authors.affiliation: Flying Instructor Training Base, Air Force Aviation University, Bengbu, 233000 China ; Engineering College of Aeronautics and Astronautics, Air Force Engineering University, Xi'an, 710038 China.
authors.forename: BaoWei
authors.initials: B
authors.lastname: Xu
authors.affiliation: Engineering College of Aeronautics and Astronautics, Air Force Engineering University, Xi'an, 710038 China ; Engineering University of CAPF, Xi'an, 710086 China.
authors.forename: YongLi
authors.initials: Y
authors.lastname: Li
authors.affiliation: Engineering College of Aeronautics and Astronautics, Air Force Engineering University, Xi'an, 710038 China.
authors.forename: JinFu
authors.initials: J
authors.lastname: Feng
authors.affiliation: Engineering College of Aeronautics and Astronautics, Air Force Engineering University, Xi'an, 710038 China.
authors.forename: JunHua
authors.initials: J
authors.lastname: Hu
authors.affiliation: Engineering College of Aeronautics and Astronautics, Air Force Engineering University, Xi'an, 710038 China.
authors.forename: Duo
authors.initials: D
authors.lastname: Qi
authors.affiliation: Engineering College of Aeronautics and Astronautics, Air Force Engineering University, Xi'an, 710038 China.
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
keywords: Dynamic model; Experiment; Optimizing search; Overturning; Submersible aircraft; Water-entry