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  #1  
Old 07-28-2009, 10:36 PM
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dbryantphoto dbryantphoto is offline
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Default Securing the shock cord to the body tube dilema

I just finished building a beautiful Estes Executioner. After having nearly completed everything I decided that I would like to install a better shock cord.. maybe some sort of nylon cord instead of the rubber band thing.

There's really no way for me to dig out the installed rubber band cord which is secured deep inside the rocket tube.

What is the best way to install a shock cord to the inside of the tube other than folding a piece of paper and gluing it inside? I was thinking of drilling a hole in the tube, tying a new and better piece of shock cord and securing it with a nice knot. The remaining knot that would be protruding outside the body of the tube... i was thinking of designing some sort of smooth cowl that would be placed over the knot... gluing it neatly and then painting to match.

Is there a better way?
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  #2  
Old 07-28-2009, 10:44 PM
stefanj stefanj is offline
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LOC used a simple and effective method:

Tie a loop in the nylon shock cord . . . a circle maybe 2" wide.

Mix up a batch of epoxy.

Lay the body tube flat.

Use a tongue depressor taped to a dowel as a spoon to transfer a nice pool of epoxy down the inside of the body tube a ways. Smear it around a little.

Lay the loop of cord right in the pool of epoxy. Use a dowel with waxed paper wrapped around it to press it firmly against the body tube. Pour on a little more epoxy so the cord is encased.

Let dry, keeping the model horizontal.
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  #3  
Old 07-28-2009, 10:50 PM
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That sounds like a great idea. So basically the cord will be attached to the inside of the body tube encased in a little pool of epoxy. I will try to get the pool of epoxy deep inside. Thanks so much. Are there any pics of this online anywhere just so I can compare my mental visual with pictures?
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  #4  
Old 07-28-2009, 10:59 PM
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Is it necessary to use the rubber band type shock cord or can I just use a nice long piece of nylon cord? Does a portion of the cord need to be eleastic?
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  #5  
Old 07-29-2009, 12:31 AM
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Night Tripper Night Tripper is offline
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I use elastic on all of my low-power builds. You can pick up a small roll in the fabric section of most any Walmart.

And btw, Welcome to YORF, Don!
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  #6  
Old 07-29-2009, 04:00 AM
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After ordering a shock cord, just to find out they use elastic bands, I went to Wal-Mart too. I started with the same width as the old rubber bands. But they tend to give out faster. Until my supply runs out (18 feet) I started doubling them up...

But I still use the old folded paper to mount them. Some of these guys post about them giving out but mine never have. But, I use so much Elmer's on them they are hard to conform to a round tube...
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  #7  
Old 07-30-2009, 09:39 AM
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Default Baffle System & Shock Cord Mount

Heres a description of attached Photos. 1) regular "cloned BB 0." 3) "Goony" Bluebird. 4) "Baffle system," w/eye bolt attachment; 5) Baffle, main body, & blast plate. Note, the kevlar passes right on thru it, but plugged and glued; 6) whole rocket in separate pieces attached w/kevlar shock cord; 7/8) side by side BB and BB0.
Forgot to take pictures of "center plate" jig. Will do that next. Glenn NAR 89197
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  #8  
Old 07-30-2009, 10:01 AM
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Default Replacement Shock Cord Mount

Referring back to your original post.......

If you don't want to use the tri-fold paper mounting system (which, by the way, has never failed for me either), you can use the mounting system used by FSI.

Basically, stiff paper or card stock, about 3/4 to an inch wide and about an inch and half long, maybe two inches. Three holes equally spaced centered on the long axis. Check this link for a description of how to mount it.

http://plans.rocketshoppe.com/fsi/f...FSI_Voyager.pdf
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  #9  
Old 07-30-2009, 10:32 AM
foose4string foose4string is offline
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Quote:
Originally Posted by barone
Referring back to your original post.......

If you don't want to use the tri-fold paper mounting system (which, by the way, has never failed for me either), you can use the mounting system used by FSI.

Basically, stiff paper or card stock, about 3/4 to an inch wide and about an inch and half long, maybe two inches. Three holes equally spaced centered on the long axis. Check this link for a description of how to mount it.

http://plans.rocketshoppe.com/fsi/f...FSI_Voyager.pdf


I used this method in my Orbital Transport clone after forgetting to attach the kevlar before the motor mount was installed, and it worked very well. I sort of combined it with the LOC method, still using kevlar(knotted at the anchor end) as the anchor line and using epoxy as the adhesive. The tri-fold works just fine, I just prefer the other methods, mainly because think they are a little less obtrusive.
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  #10  
Old 07-30-2009, 04:30 PM
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My problem with the tri-fold isn't that it fails, its that it creates a obstruction in the path of the parachute. There's enough problems with a getting a parachute to deploy properly, I don't need to add another.

Like Micromeister I us stainless steel fishing leads and beading wire mounted to the top centering ring.
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