Abstract: Based on the low density atmosphere for parachutes in the Mars exploration missions, this paper proposes a method to predict the aerodynamic coefficient of parachute by the effective porosity according to the relationship between the aerodynamic coefficient and the total porosity. This method firstly obtains the fitting curves and the permeability constants by the fabric permeability results and data fitting. According to the wind tunnel test, the aerodynamic coefficients of two effective porosities are acquired. Then, the aerodynamic coefficients of the disk gap band (DGB) parachute are accomplished from the effective porosity interpolation. And the airdrop test data has demonstrated the effectiveness of the approach proposed. The calculation results indicate that under the conditions of Mars, the aerodynamic coefficient of parachute is basically the same as the trend with varying attack angles under the wind tunnel conditions. The variation range of the parachute drag coefficient under  Ma  0.4 is from 0.583 to 0.622, and the variation range of the parachute drag coefficient of  Ma  0.8 is from 0.438 to 0.494. 

Key words: Effective porosity, Disk gap band (DGB) parachute, Mars, Aerodynamic coefficient, Wind tunnel test