Ye Olde Rocket Forum - Replacing the shockcord system

#31

11-04-2009, 03:37 PM

BEC

Master Modeler

Join Date: Feb 2009

Location: Auburn, Washington

Posts: 3,655

Quote:

Originally Posted by blackshire

I had some extra time to search this morning, and here is the link to the Apogee Components "Peak of Flight" newsletter (Issue #231) that contains Dr. Roy F. Houchin's article about the removable shock cord anchor (the article begins on page 6): http://www.apogeerockets.com/educat...wsletter231.pdf

That's slick! NOW I know how I'm going to recomission my original Astron Constellation (well, the part of it I still have after the shock cord failed and the payload section drifted ever so gently away).

Last edited by BEC : 11-04-2009 at 10:06 PM. Reason: an unmatched parenthesis

#32

11-04-2009, 08:18 PM

blackshire blackshire is offline

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Join Date: Jan 2009

Location: Fairbanks, Alaska

Posts: 6,507

Quote:

Originally Posted by cjp

I'm a bit slow on this one

,please explain.

When he was a young man, G. Harry Stine knew several scientists, engineers, and technicians who were his mentors when he was a budding rocket engineer. When he asked how he could pay them back for their help and guidance, one of them told him, "You can't pay me back. Pay it forward" (to others whom he could help and guide in the future). This motto and the Boy Scout motto ("Be prepared") are my two favorites, even though I was never a Boy Scout myself.

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#33

11-04-2009, 08:23 PM

blackshire blackshire is offline

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Join Date: Jan 2009

Location: Fairbanks, Alaska

Posts: 6,507

Quote:

Originally Posted by BEC

Thank you! As long as the rocket or motor mount has a thrust ring (engine block) the removable shock cord mount will work fine, whether or not the rocket also has a motor clip.

#34

11-06-2009, 05:47 AM

cjp

Craftsman

Join Date: Sep 2009

Posts: 112

shockcord replacement

Thanks for the explanation on( pay it forward),that is a great motto.Can't wait to use at some future launch when I can help someone.Or the next time help is needed.cjp.

#35

03-23-2011, 03:05 PM

eclindholm eclindholm is offline

Junior Rocketeer

Join Date: Mar 2011

Posts: 1

Quote:

Originally Posted by blackshire

Earlier this year, I designed a removable shock cord anchor that can be made of either thin sheet steel or resin-impregnated beveridge board (the material that Centuri/Estes fiber fins are made of). For 13 mm rockets, it can be made of steel wire. All of them can be retro-fitted into existing rockets, and they allow the anchor and shock cord to be easily removed for inspection (and to replace the shock cord, if necessary). For tandem Kevlar/elastic shock cords, they make it easy to tie the elastic to the Kevlar *below* the top edge of the body tube, which prevents the abrasive Kevlar from "zippering" the body tube.

Dr. Roy F. Houchin built prototypes of the sheet steel version, and he also wrote an article (illustrated with photographs taken by his wife) that Tim Van Milligan published in his "Peak of Flight" newsletter. The article is in one of the issues between #224 and #244. (I apologize for not being specific, but I forget which issue it's in, my computer with a link to the exact issue died a few days ago, and I have a *slow* internet connection.) The "Peak of Flight" newsletter archive is here: http://www.apogeerockets.com/educat...ter_archive.asp

I hope this information will be helpful.

Has this method been tested on larger rockets? I am building an Estes D-Region Tomahawk (D12, E9 engines) and am looking at upgrading the tri-fold elastic method. Unfortunately, I have already assembled the motor mount / fin can assembly. I found your article in the "Peak of Flight" and was intrigued in it's usage, but was unsure how it would be for larger rockets.

Best Regards

Craig

#36

03-23-2011, 07:11 PM

blackshire blackshire is offline

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Join Date: Jan 2009

Location: Fairbanks, Alaska

Posts: 6,507

Quote:

Originally Posted by eclindholm

I have never flown a model rocket that uses the removable shock cord anchor. Roy Houchin made the prototype shown on page 6 of this "Peak of Flight" newsletter issue (see: http://www.apogeerockets.com/educat...wsletter231.pdf ), and he has since flown them in 18 mm motor powered rockets with 100% success. For a 24 mm ("D" and "E") powered model, the thin lithograph tin sheet metal might work just as well, but I would feel confident using a thicker-gauge sheet metal. Ideally, I'd use 0.5 mm - 1 mm thick sheet steel (spray-painted with high-temperature engine block paint to resist corrosion from ejection charge residue) or--even better--stainless steel.

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