Based on NACA airfoils,a new type of tandem buoyancy-lifting airships with both higher utility and economy efficiency was developed.With numerical simulations aerodynamic and configuration design for buoyancy-lifting airships was investigated and buoyancy-lifting characteristics were evaluated and analyzed synthetically.It shows that a tandem buoyancy-lifting airship has considerable volume efficiency.Its lift-drag ratio is increased 50% than single wing resulted from block of airflow by posterior flying-wing and speedup of airflow in overlay field.Its deadweight can be decreased and payload is increased as velocity is higher than 30 m·s^-1.At the same time,chord wise size of tandem airship is comparatively small so that surface tension of skin material can be reduced availably.It provides a wider scope for skin flexible material selection of high altitude aircrafts.

In the present paper, the unsteady and two-dimensional magnetohydrodyna-mical equations are solved to describe the origin and evolution processes of the galactic magnetic field and galactic shock waves. The initial uniform magnetic field will wind into the spiral structures in the galactic disk, in which the magnetic field and the interstellar gas are frozen together. The influence cf the galactic magnetic field on the formation of the galactic shock wave is analyzed. As the magnetic field is not very strong, the influence is weak.