Anti-Zipper Design

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edwardw

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Here is a link from ROL - click on Anti-Zipper Design.

https://www.info-central.org/index.cgi?construction

How well does this work in pulling the chute out? I'm considering this for my L1 (since my first one failed with electronics) and needed some opinions.

What other methods are there?

Edward
 

RevKeith

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Edward,

Do a search for a TRF member named "Swimmer". He just finished his anti-zipper design based on the ROL Info Central article. Better yet, look up Swimmer in the member area and email him - I know he would be more than glad to help you.

Keith
 

Missileman

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I have not tried this method but it does kind of scare me.
It is assuming drag to pull the chute out, But if you deploy at apogee and are not moving very fast, How much drag will you have?
I can just picture a rocket falling sideways to the ground with a partially deployed chute.
Just my 2 cents
 

UhClem

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The anti-zipper system works pretty well. I have used a variation on it in several differect rockets with good results.

My variation is that the motor mount tube extends all the way to the front bulkhead on the coupler. This deletes the baffle that Stu uses but I think it results in a stronger assembly and parachute protectors are pretty easy to come by.

I have used this basic idea on rockets ranging in size from an Estes Executioner to my 6" diameter level 3 rocket. My first rocket to go zipperless was a PML Quasar. The third time I repaired this rocket after it zippered (it is the old phenolic tube version) I converted it to zipperless recovery. I have not been troubled with zippers since.

In order for the parachute to come out, you need a combination of two things:

1) The parachute fits fairly loose into the body tube.
2) The ejection charge imparts a fair amount of momentum to the nose section.


If the momentum of the nose section is sufficient to extract the parachute, all is well. If it doesn't, then you are in trouble unless differential drag between the two sections does the job.
 

Stymye

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I used the zipperless design on my L1.. and a few other kits works like a charm

I just roll the chute and cord down tword the baffle end
rather than pack it into the nose section
 

rstaff3

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I too have used this basic design with no problems. I hook the chute to an eyebolt or U-bolt on the lower section either directly or thru a cord. I wrap the chute with the shroud lines or the lower cord so it stays right at the bulkhead. That way it come out pretty much immediately.
 
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