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#1
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those pesky shock cords
I guess that I'm going to have to relearn something simple at my old age. I had more shock cords break off in the last season than I had in all the previous years in this hobby going back to '73. So what is the best way to mount a shock cord in a little BT-5 or BT-20? These are going to be for little work horse rockets like pop-pods.
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#2
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Kevlar cord tied around the thrust ring, tie the other end to the shock cord.
The old-style Estes fold-mount is very passé.
__________________
When in doubt, WHACK the GAS and DITCH the brake !!! Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't ! Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY. ALL systems are GO for MAYHEM, CHAOS, and HAVOC ! |
#3
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The tri-fold may be "passé" but, when used with kevlar, works just fine in small tubes.
Kevlar around the thrust ring works great for awhile....but somewhere between 10 and 20 flights it is going to fail from being cooked by ejection charges. Been there, done that. Kevlar in a tri-fold in the usual place below the nose cone is immune to this problem.
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Bernard Cawley NAR 89040 L1 - Life Member SAM 0061 AMA 42160 KG7AIE |
#4
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For pop-pods? I'd use kevlar and use the lariat method. Tie a loop around the nozzle end and run the line up alongside of the motor. Tape the motor in. Done. The line comes out when you remove the motor, so it's replaceable.
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-Wolfram v. Kiparski NAR 28643 - TRA 15520 MTMA Section #606 President |
#5
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I try to set up the pop pods to come down sideways so as lower the risk of kinking the pop pod tube. Just balance with an empty motor casing.
Works well for me. I just tie around the pod's cg, then tape into place. Easily replaceable, if needed. Allen |
#6
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I was wondering if I was using inferior quality kevlar that keeps burning through? Can anybody recommend a good brand of the stuff that doesn't?
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#7
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Quote:
I use this method on an old Dragonfly pop-pod boost glider a friend gave me. It works great. My kit had an engine hook, so I place the loop around the hook. And another shout out to jeffyjeep! This was several years ago, and Jeff identified this glider (it was mostly built but had no instructions, and I didn’t know what it was.) He sent me the decal for it.
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Lee Reep NAR 55948 Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor In the Paint Shop: Nothing! Too cold! Launch-Ready: Farside-X, Maxi Honest John, Super Scamp |
#8
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Just remember that these materials aren't fire proof, but are resistant. In other words, they can burn, but they stop when the heat source is removed. I've had gear over the years that have been made with just about everything DuPont and their competitors could come up with and they all have ended up with burn holes. Some of the fabrics have been Kevlar, Nomex, PBI, PBO, Lenzing, etc. in various blends.
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I love sanding. |
#9
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This is the type of mounts I use in all of my LPR.
They are nothing more than a section of manila card stock with three slits cut in them. The shock line is threaded through and glued. This type of mount is similar to the ones Centuri and MPC used in their kits back in the day. They are very sturdy and low-profile, making them ideal for BT-5 and 20 size tubes.
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Just remember...G. Harry Stine's first ever model rocket was an RTF ! Check out my wonderful model rocketry blog here: https://castlerocketeer.blogspot.com/ |
#10
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Ed, those remind me of “insulators” I made for Quest TigerTail igniters back in the 90s!
One year we bought Quest kits and motors. The kids had an awful time figuring out how to apply Quest’s insulator, so I used tractor-feed tearoffs from printer paper. Quest sent us a lot of extra igniters, and I still have many. I've thrown out lots of Aerotech Copperheads, but the Tiger Tails were very reliable.
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Lee Reep NAR 55948 Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor In the Paint Shop: Nothing! Too cold! Launch-Ready: Farside-X, Maxi Honest John, Super Scamp |
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