In a research paper recently published in Space: Science & Technology, Qi Li from Beijing Institute of Spacecraft System Engineering studied aerodynamic characteristics of two types of Mars Ascent Vehicles (MAV). Those with slender bodies and those with short, blunt cone cylinders. They studied the influence law and efficiency of the change of forebody generatrix parameters on aerodynamic performance.
The authors first proposed the aerodynamic performance demands of MAV, looking at optimization indicators for the drag performance of ascent vehicles, and identified that they should be capable of static stability in the atmosphere.
Next, they looked at the drag on the vehicles and proposed a method of selecting shape parameters of the forebody of MAV. Previous research showed that the shock wave drag of a flight vehicle in the supersonic region accounts for more than 70% of the total drag. Reducing the shock wave drag of the ascent vehicle is crucial to the lower energy consumption and system cost.
Finally, they arrived at two main conclusions:
- For slender ascent vehicles, the shape of the conical forebody can play a better role in drag reduction, and the drag performance after drag reduction can meet the demand.
- The static stability margin of the short blunt body is easy to meet because the center of pressure at a small angle of attack is closer to the tail end, so the drag reduction design of the forebody shape should be emphasized.