HOME : About DITC : Movie List : Links : Bibliography : Movie Comparison : Site Map : Search
Getting Started Select Design Task Learn About Design
What To Observe : Surface Area & Shape : Canopy Layers : Weight : String : Vents : Frame               

Changing the total mass of the parachute changes the weight, or force of gravity acting on it. You can do this by changing the number of washers, coffee filters, even cutting holes or changing string length and throwing away material.

Changing the weight will change the terminal velocity that the parachute system will reach if it falls long enough. (See "Terminal Velocity" in Key Concepts> How Parachutes Work.) After being dropped, a parachute accelerates because of the net downward force due to gravity. As the parachute's speed increases, the parachute's drag force increases (drag is proportional to the square of the speed). With more weight, the parachute must go faster for there to be enough drag force to balance out the added weight, or force due to gravity.

Example: Adding washers increase the parachute's speed, since more washers adds to the downward force without changing the drag a parachute produces. Stacking or overlapping filters also adds weight without changing the inflated area of the parachute, and so the system goes faster. Adding additional tiers of filters usually does not help because the turbulence from the lower tiers interferes with the full inflating of the canopies above. Adding a frame increases the weight, but also can keep the canopy's inflated area near to its flattened area, perhaps increasing drag force (but see surface area and shape about flat versus cupped drag coefficients). Using lots of masking tape can add to the weight without improving drag force.

Return To Top