I don't know what the stop is, but...
Take the top centering ring and drill two holes an inch apart, and
about 1/4 inch in from the motor mount hole You then pass the steel
cable down one hole and up the second. Create a loop with the end that
you fed through and crimp the ferrule. Then feed the free end of the
cable through the loop and up the tube of the rocket. Make a loop with
the second ferrule so that the top of the loop is just barely below the
lip of the body tube. Attach (quick link) a section of tubular nylon
to this and your chute/nose to the other end. You can epoxy the lower
part onto the motor mount tube if you want, but its not needed.
I've used this method on rockets from 1.9 inch diameter to 7.5 inch
diameter and it has yet to fail me. I don't know who came up with the
idea, but I've seen it in Quest rockets, Flis Kits rockets and
I don't know for sure, but it seems to have originated with North Coast
Rocketry back in the 80's, and their "Gorilla" mount. So either Matt Steele
or Chris Pearson. Apogee's Ed LaCroix adapted it using kevlar for his small
competition rockets in '88, but he wrapped the lower end sometimes around
the motor mount tube, which can also be done with HPR as well.
The HD in my area is a joke as they don't know their asses from a hole in
the ground. Lowe's has the same thing and they know what they sell, and
furthermore what the 'stops' are used for. The STOP is crimped to the tag
end of the loop--after you make the loop and crimp the ferrule. It's
included to not only protect you from getting poked by the frayed cable
ends, but it's the last line of defense should the ferrule fail.
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