06-10-2018, 10:37 AM
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Master Modeler
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Join Date: Jan 2009
Location: Fairbanks, Alaska
Posts: 6,507
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Quote:
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Originally Posted by astronwolf
Why fix what isn't broken? I've never had a tri-fold mount fail. I really disliked having them in BT-20 sized tubes when I was a kid, because they took up precious space. I mostly use a kevlar leader in rockets I build these days, and I still sometimes use the trusty tri-fold. It's a tried and true shock cord mount.
Thanks Gene!
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The problem isn't with the tri-fold mounts themselves--I agree that they're robust (especially if one smears a thin film of glue onto both sides of the assembled mount, *and* onto the intended mounting surface inside the body tube, then lets them dry before gluing the mount in place with a second coat; this "Stine-ian" double-glue joint is very strong, and also withstands ejection charges well). The problem is that eventually, the rubber or elastic cord burns through at the mount, or the Kevlar--if one is using that--frays at that point. Replacing any kind of glued-in shock cord anchor is--at best--very difficult, *BUT*:
To overcome this, I designed a "paperclip variant" of G. Harry Stine's "Shock Lock" (see: http://www.oldrocketforum.com/showt...22Shock+Lock%22 ), which allows the shock cord to be replaced when necessary; a tri-fold shock cord anchor could also incorporate this modification. (Speaking of Kevlar, "mojo1986's" Kevlar-zippered body tube repair method [see: http://www.oldrocketforum.com/showt...ock+cord+anchor ] is also well worth preserving for posterity! Especially if the model is a lovingly-constructed scale model rocket, getting a "Kevlar zipper"--at any time, but especially during a contest--would be frustrating and/or upsetting, but his repair method restores such rockets' appearance and local structural durability.) |