Parachute Descent Rate Calculator

This tool will plot the descent rate of two parachutes around the weight you specify. To use the tool:

  • Enter the parachute model you want to plot.  The primary chute goes on the left side.  The optional chute to compare with goes on the right.  Leave this blank if you do not want a second chute plotted.  The form fields will auto-populate with the chute's diameter and Cd (coefficent of drag).  
  • You can override the diameter, or the Cd, to test how a different chute would perform or the effect Cd has on performance.
  • Enter the target weight.  The default is 11 lbs (5Kg).  The plot will then graph the parachute performance based on weight.
  • Hit return to update the plot after you override values.  Or press "Update" form after changing any values.
  • Compare both our chutes alongside the products of other manufactureres products.

 

* IMPORTANT NOTE ABOUT REFERENCE DIAMETER: Reference Diameter is used to calculate the descent velocity drag area.  For Fruity Chutes parachutes, this diameter is the same as the opening diameter of the chute.  The drag area of the parachute is calculated as Pi * D / 4, where D is the reference diameter.  For flat sheet chutes like Top Flight the reference diameter is the flattened diameter of the chute, again the diameter quoted by the manufacturer.  For some manufacturers the chutes size is measured by the distance (circumference) across the canopy. Or in some cases it's just a model number and we are not sure of the exact size.  This includes Rocket Man, Spherachute, Sky Angle and Giant Leap TAC chutes.  For these the equivalent reference diameter is calculated based on the geometry of the canopy while in flight.  This then becomes the reference diameter used to calculate the descent velocity.  For these chutes you will notice that the diameter is different from the size of the manufacturer.  For example a Spherachute 120" parachute has an equivalent diameter if 76.4 inches.  But the Cd of the Spherachute parachute is set to 1.5 so the resulting descent rate matches the manufacturers data.  For these chutes the Cd is adjusted so the resulting descent rate matches the manufactureres published rates for that model.  This has occasionally causes some confusion for folks using the calculator on other manufacturers chutes.  

Descent Rate vs Weight

Impact Energy Joules vs Weight

Calculator Summary

 

  • Enter the parachute model you want to plot.  The primary chute goes on the left side. The optional chute to compare to (with) goes on the right.  Leave this blank if you do not want a second chute plotted.  The form fields will auto-populate with the chute(’)s diameter and Cd (coefficient of drag).  

  • You can override the diameter, or the Cd(,) to test how a larger chute would perform or the affect (effect) Cd has on performance.

  • Enter the target weight.  The default is 11 lbs (5Kg).  The plot will graph plus and minus the target weight. (sounds awkward)

  • Hit return to update the plot after you override values.  Or press Update form. (...override values, or press “Update.”

  • Compare both our chutes, as well as other manufactureres products. (Compare our chutes alongside the products of other manufacturers.)

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