Abstract: Model flight test is one of the important methods in aerodynamic research and has become a low-risk and effective technical approach for aerodynamic study and for demonstration and validation of aerodynamic configuration. Nowadays the technology of low speed model flight test becomes more mature but there are still some severe technical problems in high speed model flight test, especially in supersonic model flight test, such as insufficient engine thrust and sharp increment of short period oscillation frequency. A typical battleplane as an example. It can be seen that the scale number K is the key parameter. Based on a BWB (blended wing body) aircraft C2 designed by China Aerodynamic Research and Development Center(CARDC), a new supersonic model flight test scheme is investigated in this paper. The BWB aircraft was carried to 22km high by a giant helium balloon and then droped, the maximum flight Mach number reached 1.18, the thought using gravity to overcome shortcomings of insufficient engine thrust is worthy of recognition.