Steel leaders and zippering.

After a long, idle summer in my hot, AZ garage all my stock Estes rubber shock cords need to be replaced. I bought some steel fishing leaders longer than the rockets so make future replacements easier, but as I stared at the excess leader sticking out the top of the BT I realized that if something went wrong this cable would zipper the *&%#$ out of my rocket.

Do I need to get shorter leaders, or do you guys know a good way to prevent this? Some are minimum diameter rockets with little room for extra bulk.

Use Kevlar cord. It is flame-proof, so you don't have to replace it, and also, it is a little bit wider than the steel cables.

I never had any problems with steel leaders, knock on wood. :bang: I wrap them around the motor mount, then a small notch in the centering ring.

It is basically the same method as using Kevlar.
(Forgive the quality of the pictures)

Same method that's used to prevent Kevlar zippers... wrap some masking tape around the leader right where it'd go over the lip of the tube, so that it bears on a larger surface area and is "cushioned" by the tape, to prevent it from cutting into the tube wall and starting a zipper...

Later! OL JR

Has anyone tried heavy spider wire for estes size rockets I think it is Kevlar just green.

I could be totally wrong, and I've never used a steel leader... but isn't it supposed to be completely inside the airframe - not sticking out of the top? I thought you attach the shock cord (elastic, Kevlar, whatever) to the leader - inside the airframe. I'm sure there are different ways to do it - but I get the OP's concern, the thin steel wire will zipper the tube much better/easier than the elastic he has been using.

One good high speed deployment and that thing will slice through your rocket like a hot knife through butter.

Get one a couple inches shorter. You can pull the end back through the motor mount to change the elastic.

The only reason I have the leader above the BT is for easy shock cord access for changing. Once the dog barf is in, I curl the leader down with the shock cord then the 'chute. On some models I have glued the leader about half way down the BT, for less movement.

I use leaders a lot in my BT50 and up rockets, but I end the leader a bit before the end of the body tube so it wouldn't stick out and be prone to zippering. If I'm worried that I'll have to replace the Kevlar that attaches to the leader, I'll make sure it is within easy "fishing" length.

my level one rocket has a steel leader in it no problem but i was told to put a paddle ball ball at the top of the tube just slice the ball insert leader and what ever you use to tie the nosecone to the steel leader dont use underwear strapping maybe some kevlar....but anyway that will prevent zippering because of the leader! then tape the ball so it doesnt fall off!

^^-- "underwear strapping" solves an engineering problem, and so does elastic in a shock cord.

apburner said:

Has anyone tried heavy spider wire for estes size rockets I think it is Kevlar just green.

Click to expand...

If Spider Wire is anything like Spider Line, then it has very little heat tolerance. I have 500lb test Spider Line, and it's great for flying a stunt kite... That said, if it crosses any kind of other line, and I get a wonderful view of $1K+ of kites doing a death spiral onto anyone unlucky enough to be under it.

Seems like a well placed plastic bead would prevent zippering.