A new coupling model of dynamics and thermodynamics to predict trajectory of stratospheric airship during ascent

Predicting the trajectory of the airship during its ascent before it is released has significance in avoiding possible accidents. To achieve this, a new coupled thermodynamics and dynamics model is developed. A rigid body model with 6 degrees of freedom is adopted. Time-varying aerodynamic forces and mass distribution parameters are also included in this model. The thermodynamic model considers the heat transfer process of radiation and convection among the film of airship, helium, internal air, and atmosphere. The simulation results show that more accurate results can be obtained using the rigid body model with six degrees of freedom compared with the three degrees of freedom model. The existence of the sunlight will also affect the movement of the airship, which will cause the temperature of the buoyant gas to increase and the airship to move faster. Some factors which will affect thermal behavior of helium are also investigated. Results show that the larger the initial helium volume is, the more serious the supercooling phenomenon of helium will happen. The greater the solar radiation absorptivity of the film is, the lower the supercooling temperature will be, but it will cause helium more hotter during floating stage. The overpressure of the airbag has no significant effect on the motion of the airship.