Originally posted by akpilot
There's as many answers to this question, as there are people who'll give you advice . . .
Typically the first thing I personally do, before starting to build, is to get rid of the Estes elastic cord - from experience it's just too short. Then I can take one of two directions:
1) Depending on the model, I substitute the elastic with kevlar thread that is at least 3x the length of the body tube. I put a small hole into the top of the MMT. Then once the MMT assembly is glued and built, outside of the model, I tie the kevlar around the MMT, between the centering rings. I apply a small bead of epoxy on the knot, to ensure it holds. Once tied I then thread the kevlar up through the hole in the MMT and tie it to the NC. Glue the assembly in the BT, bringing the kevlar up through the top.
The second method is;
2) Do pretty much the same as No. 1, except I end the kevlar about 2-3", after it leaves the BT. Then I use a swivel and tie 1/8" or 1/4" elastic to the swivel (e.g. the kevlar is tied to the rocket at one end and the swivel at the other, the elastic is then tied to the other end of the swivel and then attaches to the NC.
Either way, just make sure that whatever method you use the combined length of kevlar and/or elastic is at least 3x the length of the body tube.