#### Machet_Man

##### Well-Known Member

- Joined
- Feb 5, 2012

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Right now I'm working on quantifying some of the parameters surrounding the recovery system on our collegiate sounding rocket team and was hoping to find some insight from some of the experienced members.

I have being trying to use the infinite mass method for analyzing the opening force of the annular parachute but it seems to be very sensitive to certain coefficients that I don't have a lot of reliable data to calculate, including the opening force coefficient c_x and also the force reduction factor (x_1). Here is the simplest form of the equation for those who are wanting to follow along.

F_Opening = c_D * S * q * c_x * x_1

Does anyone have any information on how to calculate the opening force coefficient and force reduction coefficient besides extrapolating graphs?

Maybe I should ask first, does anybody know of a better way to go about finding the force exerted on the rocket by the inflation of the main parachute? I can also use the inflation time to find the max opening force if anyone has any documented method to find this parameter. I appreciate the help everyone.

Tripp