Analysis on the Optimal Transfer of the Stratospheric Airship in Wind Field

The problem of transferring the stratospheric airship from current position to desired position in stratosphere is analyzed. The reachable criterion is presented and the optimal transfer trajectory is derived. The energy consumption and transfer time adopting the optimal transfer trajectory are given. Under the assumption of both the airship speed and wind speed are constant, it is proven that the airship can transfer to arbitrary position if the airship speed is greater than the wind speed, otherwise there exists a reachable region. The optimal transfer trajectory of the airship is the straight line from the starting position to the terminal position. A numerical example is given to show how to judge whether the transfer is feasible, and how to solve the transfer time and the track angle of the airship.