To break the crucial technical difficulties of controllable aerostat in near space,and make it possible of controlling aerostat going and returning between ground and near space,the conception of solar powered radial transformable airship was raised,and it's parameters estimation method was given.The method was based on Archimedes theory and Li-style transformable airship theory.The self-adapting and controllable-transformation of sectional area was actualized by radial transformation of structure,net lift ...