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Parachute sizing was found using the drag force equation at the bottom left corner of figure 6. Putting in average assumed values resulted into a previously made spreadsheet calculator resulted in a total diameter of roughly 8 9 feet and a reefed diameter of roughly 3 feet .(updated on 10/25 to account for 80lb wet mass, not 70lb. This caused an increase in main parachute diameter from 8ft to 9ft, and minimal change in drogue diameter).
Figure 6 Spreadsheet calculator and values used
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Using the values in the spreadsheet, the shock force was found on OSCalc as shown in figure 7. For the drogue opening at 30000 ft, the upper bound of force is calculated to be 5051.58 57 slugs*ft/s^2. For the main deploying at 2000 ft, the upper bound of force is calculated to be at 584740.9 4 slug*ft/s^2 (values recalculated on 10/25 to account for 80lbs wet mass, not 70lbs).
(drogue main parachute) 
(main drogue parachute)
Figure 7 OSCalc results
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