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Parachute - Recovery: HELP PLEASE!!!!

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Parachute - Recovery: HELP PLEASE!!!!

Old 04-20-2009, 09:43 AM
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Default Parachute - Recovery: HELP PLEASE!!!!

Hi guys;
I'm one of the RC planes and UAV field but now I've some straigth questions:
1- Can anybody tell me how much does it weighs a complete 2m diameter parachute system? What does it include? Packed dimmensions?
2- How do you match rocket weigh with parachute diameter? or How do you choose "that" parachute for "this" rocket?

I've fount this parachute on internet but I've no idea of how to use them...

https://www.discountrocketry.com/mod...ry-c-7_28.html
http://www.redarrowhobbies.com/top_flight.htm

My intention is to recover a plane that weighs about 4.5 Kg safely (normal landing is not allowed.

Thanks on advance;

Guille
Old 04-23-2009, 08:00 AM
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Default RE: Parachute - Recovery: HELP PLEASE!!!!

First thing you have to do is decide what kind of landing speed your plane can handle. Most descent calculators will give you the descent rate in feet per second (FPS). We normally shoot for somewhere between 18-25 FPS depending on the construction/fragility of the rocket.

I plugged in 60 inch round chute for 4.5 kilos and got 23.21 FPS descent rate.

I think you'll need to be well under 20 FPS. Planes have more stuff to break than rockets.

Here's the link to a descent calculator if you want to play with it yourself.

http://www.onlinetesting.net/cgi-bin/descent3.3.cgi

Bob
Old 05-01-2009, 07:07 PM
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Default RE: Parachute - Recovery: HELP PLEASE!!!!

Consider a hemispherical chute, they use less material (smaller packing) and they have a higher Cd (higher drag). They also add quite a bit of stability over parasheets, so your plane will not swing and hit the ground softer. I would say that you will need abou a 10-15fps decent rate.

www.spherachutes.com (I am not sure if these will ship to Italy, but there are plenty of websites that provide patterns to make your own)

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