In a parachute, an increase of drag force occurs when the frontal area or the area of its canopy is increased. To prevent the technical problem in deployment of large parachutes, designing parachutes consisting of more than one canopy with smaller frontal area with an air vent at the top of each one is suggested. In this investigation, several formations of canopies are considered, and all are set as concentric and is placed at the top of each other with some distances apart. The canopies are taken as solid bluff bodies (Hemi-spherical cups) for simplicity. The effect of two variables on drag is the main idea of this study. All the formations of the two canopies (Two bluff bodies) are based on two variables; the diameter ratio (The diameter of the upper canopy to the lower canopy), and the distance between the canopies. The drag force is found at maximum, when the upper and the lower canopies have equal diameters, and for when the distance between the canopies is twice the upper canopy diameter.

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