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 done having measured the weight of the rocket accurately upon landing. In addition we had precise information on the parachutes themselves and used altimeters to log the data. Factors that affect the coefficient of drag are altitude, barometric pressure, air temperature, and humidity. The factors listed here, given that altitude stays constant, can vary the Cd 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.

 

Fruity Chutes Iris Parachute Cd Performance Log
Rocket, Drone, or Company	Who	Chute Used	Date	Diameter (in)	Recovery Weight Lbs	Descent Fps	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
Mag Max	GE	IFC-72	6/12/2011	72	15.6	13.667	2.562
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
						Average Cd	2.586

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