Sportech

Parachute Canopy Area for a Descent Rate: Nominal Diameter, Descent at Altitude & Canopy Fabric Mass

Halve the descent rate and the canopy needs four times the area: drag grows with the square of speed.

Load & Descent What the canopy must carry
kg
m/s
Cd

Based on the nominal canopy area, from the maker or test data for the canopy type. It differs widely between types; this default is only a starting value.

Air & Fabric Conditions and canopy material
kg/m³

1.225 kg/m³ is the International Standard Atmosphere at sea level; hot or high sites are lower.

kg/m³
g/m²
%

Canopy Area Needed

— m²

Weight divided by half the air density, the drag coefficient and the square of the descent rate

Canopy

Nominal Diameter (Circle of That Area)
— m
Weight to Support (Drag at Steady Descent)
— N
Descent Rate in the Thinner Air
— m/s
Kinetic Energy at Landing
— J
Same as a Free Drop from
— m
Canopy Fabric Mass incl. Seams
— kg

At a steady descent the drag equals the weight, and drag is half the air density times the drag coefficient times the area times the speed squared; gravity is taken as standard, 9.80665 m/s². The drag coefficient is yours: it is defined on the nominal area and differs widely between flat circular, conical, cross and ram-air canopies, and with porosity. Opening shock, oscillation, wind drift and the lines are not part of this. The equivalent free drop is the height from which the load would land at the same speed with no air resistance. **This is an estimate for planning and education, not the design of any parachute that people or valuable loads depend on: life-safety parachutes are designed, tested and certified by their makers.**

Parachute Canopy Area for a Descent Rate: Nominal Diameter, Descent at Altitude & Canopy Fabric Mass — free, with the formula and a worked example, at Textile School.