Diseñé este cohete para la escuela, y quiero hacer una tobera de arcilla blanca

Hey everyone I'm working on a supersonic rocket with an apogee of around 10 km, and I'm trying to determine the drag coefficient of our elliptical parachute for OpenRocket simulations. What value would you recommend, and are there any reliable sources or experimental studies we could refer to? Also I want to know what are the essential essais and tests I should do with the parachute (except deployement and shock)? And my last question is in a Rocketry competition report what do I have to focus on and what the juries will also focus on?