Ive been looking around for different sizes of elastic shock cord. Im new to all this.....isnt there some place locally I might be able to find it ? Honestly, I havent even seen any online retailer that lists it. Where should I look ? Fabric store maybe ?
Thanks
Don't use elastic, use kevlar (for small airframes) or nylon. Elastic will wear/tear/burn too quickly. Make sure you double or triple the length you would have used with elastic.
A bigger, better fabric store will have a good selection of various widths on rolls where they'll cut off as many yards as you want. Usually the elastic is in the "Notions" department (or just ask where the elastic is). If they have "swimsuit elastic", it's better than regular elastic because it has cotton instead of polyester that can stand up to the heat during ejection better. The swimsuit elastic is kinda biege while the regular stuff is bright white, but the regular will do if you don't luck into the swimsuit elastic. Also places like Walmart have prepacks of a few yards (less width selections) in their fabric department. -- Richard "25% off sale at the massive G Street Fabric" Hickok
Plus there's that nasty ***BOINNNNGG*** effect that brings the parts together again. ;)
Never, never, never use underwear elastic for shockcord. Why the kit manufacturers put this crap into kits is beyond me... well, I DO know why. It's to save a couple of bucks on the cost of the kit.
Use kevlar cord, kevlar strap, etc. It costs a couple of bucks but you won't be digging your rocket out of terra firma with a shovel due to shock cord failure. And you won't be removing the dents caused by what is called in technical terms the "boing-boing-bam" effect.
Try Pratt Hobbies. I use their kevlar in everything I build - it is untreated and absorbs adhesive better. And besides, Doug's a nice guy.
And by the way - while you are ordering. Order a couple of Doug's Micro Beepers and spare batteries. It'll help you find your rocket when it lands in the grass. CHEAP insurance. I can tell you for a fact from experience.
Good luck. And FORGET the underwear elastic. It just doesn't make sense to use it on anything.
Murray
Well, that's one point of view. I've used elastic on rockets upwards of
2lbs., with no ill effects. If the recovery system is prepared correctly, (enough dog barf or nomex is used) elastic will hold up just fine. As far as the "boing-boing-bam" effect, it hasn't been the case with my rockets. As stated, using at least 2 1/2 to 3 times the length of the rocket for the shockcord will keep this effect to a minimum. Now, you have another "point of view" ;-)Stones
Your local Wal-Mart or K-mart or Target or whatever should have it in their homemaking section. I bought some 1/8" and 1/4" elastic cord there last week specifically for that very purpose. It's a whole lot cheaper than buying "Shock Cords" from ESTES or other makers. I've seen it in sizes up to 1". I'm sure it's available in larger sizes if you need it. Might have to go to a fabric shop for that.
I wonder if anime-style catgirls have elastic kevlar in their undergarments... it would explain much...
-- Chuck Stewart "Anime-style catgirls: Threat? Menace? Or just hauling out weapons?"
Fabric stores for sure. Even Michaels or Hobby Lobby should have it. ANy place that sells sewing stuff. You can get it in short hanks, large hanks, or off the spool. For sexy rockets, you can even get it in black.
One thing to watch for, especially on the smaller stuff used for questes sized models. Try and STRETCH a piece of it before you buy it. SOme of the cheap stuff will show lace like holes in the weave. DO NOT USE THIS FOR ANY SIZE ROCKETS! It will break or burn the first use. The more dense weave will work fine for MR, LMR, and even HPR up to a few pounds, given the right size material.
Always use twice as much length as you think you need!
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
The elastic to look for is "Braided" nylon elastic. It is the best and strongest.
Karl Perry QUARK, Cincinnati, OH
The key is that you don't want to use elastic SC - at all - ever..
Use TN or kev thread, long enough to allow for the charge. The elastic stuff can actually CAUSE damage, if for example, the NC slaps back and knocks off a fin! You can easily put 5' of kev thread on an estes alpha, and not worry! (yes I've done it)
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