Small Diameter Shock Cord Attatchment Methods

So I'm almost done with my first scratch built and designed rocket, but have a question. What method would be best to attach 100# test kevlar thread to a 29mm phenolic PML body tube? The rocket is 36" long with a PML urethane nose cone, and TTW fin mounting to a 24mm MMT. The best method I can think of is a Estes knock off. Use a folded paper attachment point, in the forward airframe body, and epoxy it in place. It doesn't seem practical to use any kind of bulkhead with screw eye, given the motor ejection. Any suggestions?

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I've had good luck with kevlar loops epoxied inside the body tube, below where the shoulder of the nose cone will reach. Rough up the area inside the tube. Wrap the kevlar around 3 or 4 fingers, 3 or 4 times and cut. Tie a knot at one end and dip the knoted end in epoxy then stick it to the inside of the tube. Cover the epoxy/knot with masking tape to make a smooth surface. Attach shock cord to the loops.

da rmr plumber Gary R Goldenbaum NAR #73669 L1 Northwest Florida remove 'nichspam' to reply

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I use piston ejection a lot and mount recovery cords in a similar manner in my non-piston rockets. With kevlar, I'll glue it to/around the MMT and feed it through the forward centering ring. Or, I'll loop it around a piece of coupler tube and glue that assembly several inches down in the body tube.

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Here is an idea I tried that worked ok. It is a variant of the Quest MMT attachment. I used a piece of the woven Kevlar thread and fed it thought the MMT attaching it to the base of the rocket. I gave me two advantages.

1 - It increased the amount of friction in the MMT so I cut back on the tape.

  1. I can easily replace it.


Reply to
Al Gloer

That was used with the first USR kit, the Hi-Test 2650 (3 cluster 2 stage 29mm).

Different fins than either the Omega or the Alpha :)

I used the wire mesh from coax and knotted the end so it was held by the motor thrust ring. It lays flat, is strong and can withstand many ejections. You tie the shock cord or line to that.

Just Tech Jerry.

Reply to
Jerry Irvine

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