Iris Ultra Parachutes Cd Performance Log

The table below shows our measurements done over a period of 5 years to accurately determine the coefficient of drag (Cd) of the Iris Ultra Parachutes.

All tests were performed after having measured the weight of the rocket upon landing. In addition, we had precise information on the parachutes themselves and used altimeters to log the data.

Factors which affect the coefficient of drag include:

  • altitude
  • barometric pressure
  • air temperature
  • humidity

Given that the altitude stays constant, the factors above can cause the Cd to vary by up to 20%. Fruity Chutes rating of 2.2 Cd is considered to be very close to the worst case that we had measured over many flights.

Drone, Rocket, Company Tester Parachute Date Diameter (inches) Recovery Weight (lb) Descent Speed(ft/sec) Calculated Cd
Frontal Area

Mag Max

GE

IFC-72

4/1/2011

72

15.53

15.05

2.103

Mag Max

GE

IFC-60

5/20/2011

60

16.1

17.9

2.219

Comp 4

GE

IFC-72

5/21/2011

72

23.3

16.95

2.487

Comp 4

GE

IFC-72

4/7/2012

72

22

18

2.083

Comp 4

GE

IFC-72

5/19/2012

72

23.6

16.85

2.549

Comp 4

GE

IFC-72

6/16/2012

72

23

16.75

2.514

Not sure

DR

IFC-60

7/20/2012

60

16.8

18.5

2.168

Max Maxx Thunderdome

GE

IFC-72-ZP

1/2/2016

72

19.025

13.97

2.990

MN Drone

Ido

IFC-66-SUL

1/22/2016

66

13.78

14.57

2.369

MN Drone

Ido

IFC-66-SUL

1/22/2016

66

13.78

12.66

3.138

MN Drone

Ido

IFC-66-SUL

1/22/2016

66

13.78

13.06

2.949

MN Drone

Ido

IFC-72-SUL

1/22/2016

72

13.78

12.7

2.620

MN Drone

Ido

IFC-72-SUL

1/22/2016

72

13.78

11.45

3.224

MN Drone

Ido

IFC-72-SUL

1/22/2016

72

13.78

12.57

2.675

MN Drone

Ido

IFC-72-SUL

1/22/2016

72

13.78

12.04

2.916

Mag Maxx Thunderdome

GE

IFC-72-ZP

2/6/2016

72

19.025

15.6

2.398

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