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Is it possible to test recovery systems on the ground?

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Ccolvin968

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I'm wondering if there is a way to test my deployment of my parachute on the ground?
I'm attempting my level 1 cert on the 29th and am kind of nervous... not sure why.
Simulations show everything will go fine, but I've never packed a "big" chute before. (For rockets at least.)
Any tips or suggestions? I'm sure there are a million ways to fold the chute, but it's trying it out that will make me feel better... maybe...
Thanks for any advice!
 

GregGleason

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There is a concept called the "ground test".

It usually involves testing the amount of pyro composition you have for your deployment charges to see if it is adequate for good separation.

You can also test how the recovery gear deploys as well if you pack like you would at launch.

I did a ground test last Friday for a launch the next day to see if the recovery gear would deploy like I wanted.

As far as how to pack a chute (at least one way that works) see the attachment.

Greg

View attachment CJL Parachute Folding.pdf
 

Banzai88

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Ever since I started packing all of my cloth parachutes, low, mid, and high power with this method, elliptical or flat parasheets, I haven't had a single packing related deployment failure.

[video=youtube;ZFhNqC9goXU]https://www.youtube.com/watch?v=ZFhNqC9goXU[/video]

The key to packing shroud lines to prevent tangles, whatever your method, is to WRAP the shroud lines around the bundle, not twirl and twist! Proper wrap technique is shown at the 1:20 mark.
 
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ttabbal

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Pack the chute as mentioned, rig the rocket up like you will for launch. Don't forget protection for the recovery gear.

For AT motors, you can install the case with closures and feed a wire through the ejection charge hole. Put some BP in a container, even a cut-off finger end of a rubber glove works well, and install an ematch or whatever ignitor you have available. Even a bit of really thin wire will work. Connect the other end of the wires to a launch controller and fire it. Make sure everything comes out and would be in the airstream if the rocket were falling.

If you don't have a motor case yet, or it's not able to be used that way, you can plug the motor tube with whatever is available. I've seen people stuff it with rags and tape over the end of the motor mount tube. A bulkhead that fits in the motor retainer would work well...
 

Pat_B

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You can also fly your rocket with a high impulse motor that's not considered HP. I'm surprised that it's not more common to do that. Far too many L1 cert flights start out with the rocket never having been flown with lower impulse motors like some the G motors that aren't HP.
 

ksaves2

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Yes to ground testing if unsure. The 1.3gm charge supplied with AT 29mm reloads should be enough to blow the chute in all but the largest volume rocket. If you don't have electronics, ematches, BP or powder canisters, it's hard to do any testing though.
You can use the online ejection charge calculators for some assurances but if the chute pack is "really" tight, could take more BP.
Kurt
 

KennB

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You can also fly your rocket with a high impulse motor that's not considered HP. I'm surprised that it's not more common to do that. Far too many L1 cert flights start out with the rocket never having been flown with lower impulse motors like some the G motors that aren't HP.
An excellent suggestion. Too many people have GO fever and throw their L1 rockets up practically while the paint is still wet. I've only seen a few "used" rockets going up on their first L1 motor but those flights have never had a problem certifying.

While the OP is asking about ground testing, you really can't beat an active systems checkout. It would also be acceptable to have another L1 certified flyer put it up on the same motor you'd use to certify before you make your attempt; that would be the best test of them all.
 

blackbrandt

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All you have to do for a pre-cert check is ask a L1+ flyer to sign their name on the flight card.
 

Coop

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Ground testing CTI 38mm is easy. Make a 1.3g 4f charge, into which you have an igniter (ematch, quest igniter, whatever). I made a pair of leads with alligator clips that I run through an old 38mm nozzle. Charge to clips, nozzle screwed into case. Estes controller to end of leads. Point nose in safe direction. 5,4,3,2,1, pop. Observe results. Formulate plan for remediation, repeat as desired until predictable results achieved.

Later!

--Coop
 
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