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  #21  
Old 06-09-2018, 08:00 PM
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ghrocketman ghrocketman is offline
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I use the Kevlar leader method and tie tubular elastic to that. Always at least double the length of the cords Estes uses in their kits. I think Estes uses JOKE-length cords as a conspiracy to sell more kits due to the inevitable damage upon ejection. Also lean toward same theory regarding "shotgun" ejection charges. The ejection charges in motors from the 70's to 90's were far more consistent and milder but plenty effective.
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  #22  
Old 06-09-2018, 09:05 PM
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Jerry Irvine Jerry Irvine is offline
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Quote:
Originally Posted by ghrocketman
I use the Kevlar leader method and tie tubular elastic to that. Always at least double the length of the cords Estes uses in their kits. I think Estes uses JOKE-length cords as a conspiracy to sell more kits due to the inevitable damage upon ejection. Also lean toward same theory regarding "shotgun" ejection charges. The ejection charges in motors from the 70's to 90's were far more consistent and milder but plenty effective.
So can I fairly say conspiracy theory??
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  #23  
Old 06-10-2018, 11:01 AM
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Quote:
Originally Posted by BEC
Steve,

Your question got me to wondering myself. I just went though back issues of MRN here on YORP and the trifold shock cord mount is detailed in the same issue that also marks the first appearance of the Alpha. The starter set with the Alpha is on page 3, the shock cord mount in the "Idea Box" on page 5: http://www.oldrocketplans.com/mrn/m...3/MRN_V5_N3.pdf

This particular issue has credits of Publisher - Vern Estes and Editor - Bill Simon. Some earlier and later issues name Gene Street the illustrator. That's at least circumstantial corroboration for what Bill Simon told me about the mount.

Here are the illustrations from MRN V5 #3 and the first version of the Alpha instructions. Pretty durn similar.
Gene Street was also a kit designer (the Nighthawk pop-pod boost-glider was one of his designs), so he had the design experience to do it.
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  #24  
Old 06-10-2018, 11:10 AM
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Quote:
Originally Posted by BARGeezer
Thank goodness for the invention of the tri-fold shock cord mount. I remember the days of my youth when the only method in popular use was a double slit in the body tube, then feeding the rubber or elastic cord through and knotting the end. Quite unsightly.
However, most modelers nowdays use a kevlar leader tied to the motor tube. Yet Estes still clings to the tri-fold mount. I haven't seen a single Estes kit that uses kevlar. Have you? Time for Estes to come into the 21st century, methinks.
Although I admittedly have "a horse in this race," I'd love to see them offer *removable* shock cord anchors like these (which my friend Colonel [and Dr.] Roy Houchin kindly tested for me): http://www.apogeerockets.com/educat...wsletter231.pdf . They enable inspection of the Kevlar and/or elastic shock cord whenever desired, and make replacement of old, worn shock cords very easy.
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  #25  
Old 06-10-2018, 11:37 AM
BARGeezer BARGeezer is offline
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Quote:
Originally Posted by blackshire
Although I admittedly have "a horse in this race," I'd love to see them offer *removable* shock cord anchors like these (which my friend Colonel [and Dr.] Roy Houchin kindly tested for me): http://www.apogeerockets.com/educat...wsletter231.pdf . They enable inspection of the Kevlar and/or elastic shock cord whenever desired, and make replacement of old, worn shock cords very easy.



Speaking of which THANK YOU for the innovations of the removeable kevlar shock cord mount and the "extended" Stine shock cord mount. I was skimming through a summary of Chris Michealsson's blog posts about shock cord anchors that lakeroadster (TRF) had compiled at Rocket Reviews, and your name had come up in conjunction with these. Saw this just a couple of days ago, and was surprised to find out you are somewhat of an inventor besides a knowledgable scale model enthusiast!. We all owe you a debt of gratitude. Bravo!
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  #26  
Old 06-10-2018, 11:37 AM
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Quote:
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!
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.)
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  #27  
Old 06-10-2018, 11:44 AM
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Quote:
Originally Posted by BARGeezer
Speaking of which THANK YOU for the innovations of the removeable kevlar shock cord mount and the "extended" Stine shock cord mount. I was skimming through a summary of Chris Michealsson's blog posts about shock cord anchors that lakeroadster had compiled at Rocket Reviews, and your name had come up in conjunction with these. Saw this just a couple of days ago, and was surprised to find out you are somewhat of an inventor besides a knowledgable scale model enthusiast!. We all owe you a debt of gratitude. Bravo!
Thank you! Wow--I didn't know that Chris had compiled a list of shock cord mounts (or that lakeroadster had collected them all together), let alone that he had mentioned me in it. I'm touched--thanks to all three of you (and this came at a particularly helpful time)!
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
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