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Best way to attach string to body tube?

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Byron.A.Young

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Hi I'm trying to make rockets as inexpensively as possible. We've tried using the estes method except with kite string attaching the tube to the nose cone. We've tried string in a piece of paper with some wood glue, and attaching the paper to the rocket, but the string slip out and the rocket comes down in pieces (might have something to do with the fact that we're trying to build and launch these in an hour or two). We've also tried using duct tape instead of paper, and putting some super glue over that, but that doesn't seem to work either.

I was thinking of just switching completely to the standard elastic cord, but this is more expensive. Any ideas? Thanks and check out some of the pictures from my outreach program here:

http://www.rocketryforum.com/showthread.php?t=1086
 

Gillard

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if you have to use string, try fixing it to the motor mount quest style. the kite string will rip out the mount if there is a sudden snap, so either lengthen the string, and/or use frangable links, these are loops in the string covered by sellotape. the loops open as the cord lengthens but take alot of the energy out, so there is lessstrain on the mount.
 

dr wogz

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Or, tie a loop in the string, and embed this loop in a dab of epoxy. make sure you get all teh loo & knot in teh epoxy. Fray teh loop a bit, so the epoxy has lots to hold onto..

I've tried this with Kevlar, but the kevlar pulled out. Inital thought was that the kevlar was waxed / oily. This system was used on my LOC Vulcanite, and it's anchor was a woven nylon 'string'.. seems to work.

Also ensure enough length to help dissapate the 'shock'
 

cjl

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if you have to use string, try fixing it to the motor mount quest style. the kite string will rip out the mount if there is a sudden snap, so either lengthen the string, and/or use frangable links, these are loops in the string covered by sellotape. the loops open as the cord lengthens but take alot of the energy out, so there is lessstrain on the mount.
I'd be concerned with the string burning through with this though. Honestly, I'd just go with some kevlar tied around the motor mount - kevlar thread is surprisingly cheap in decent quantities.
 

Byron.A.Young

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I'd be concerned with the string burning through with this though. Honestly, I'd just go with some kevlar tied around the motor mount - kevlar thread is surprisingly cheap in decent quantities.
I think I'm going to try to use elastic cord, which should reduce the impact on the attachment. If this doesn't work I'll start using kevlar cord.
 

cjl

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That should work. If you get full spools of elastic, you can get it quite a bit cheaper than the stuff from Estes.
 

talkin Monkey

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For some of my "quick build" Estes stuff I picked up some plain white (and flat) shoe laces and used that in lieu of the elastic. I also used epoxy to secure it to the body tube instead of the paper fold thing.
 

RoyAtl

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Hi I'm trying to make rockets as inexpensively as possible. We've tried using the estes method except with kite string attaching the tube to the nose cone. We've tried string in a piece of paper with some wood glue, and attaching the paper to the rocket, but the string slip out and the rocket comes down in pieces (might have something to do with the fact that we're trying to build and launch these in an hour or two). We've also tried using duct tape instead of paper, and putting some super glue over that, but that doesn't seem to work either.

I was thinking of just switching completely to the standard elastic cord, but this is more expensive. Any ideas? Thanks and check out some of the pictures from my outreach program here:

http://www.rocketryforum.com/showthread.php?t=1086
Do it the way the original model rocketeer, Orville Carlisle, did it in 1954. Poke a small hole through the body tube about an inch to an inch and a half below the nose cone. Take your string or elastic and tie a big double knot in one end. Thread the other end into the hole and pull out through the middle of the body tube until the knot stops it. Put a small dab of glue there.

Sure, it'll be ugly, but it will do the job. If they keep building rockets they can then learn the prettier ways of doing it.
 

powderburner

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Byron,

If you are trying to build-n-launch all within an hour, it sounds like you may be rushing it a bit.

If you really want to do this you will probably have to deviate a bit from cheapo materials and supplies, and from the first-time builder doing it all himself. White and yellow glues (water-based) have a drying time of several hours; I would recommend a minimum of overnight. About the only way I can think of to make glue joints work that quickly would be to switch to CA, and I cannot recommend that you allow first-timers (especially children) to handle CA adhesives. This turns your build-n-launch session into a watch-the-teacher session and still blows through your notional one hour.

It looks to me like you would have to use something like RoyAtl suggests. You are going to need a "mechanical" attachment instead of an adhesive one (at least, a water-based adhesive one).

One other possibility: an external attach point. Poke a small hole through a fin root, pass one end of the tether cord through and double-knot, attach the other end of the tether to the recovery system and NC. When you prep the rocket for launch you install wadding, recovery, shroud lines, etc as usual, and tuck in as much of the tether as will reach up the outside to the front of the BT, then put the NC on top. This means that a portion of the tether cord will be outside the rocket during ascent, but that is OK, as I doubt that the rest of the first-timer's rocket has been optimized for minimum drag.
 

El Cheapo

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in just perusing (sp?) this thread quickly.....my answer would be to use the thread as if you were using Kevlar on a mid-high power application. That means lots of it. Try using say 6-7 times the length of the rocket. That will give the nose cone sufficient amount of time to slow before tension is placed on it.
 

RoyAtl

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Nah, there's no reason to. These are kids rockets, Alpha-sized and that much shock cord is just going to be a hassle for them to pack into the rocket. Just keep it simple. 18" of twine, external knot, through the body. Will work just fine.
 
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