LPR Question: 120 pound braided dacron polyester kite line as shock cord?

[brockrwood]

I have a big spool of 120 pound braided dacron polyester kite line. The stuff is super strong. Heavy, but strong.

Can I use it as shock cord line in my LPR model rockets?

It is not heat resistant like kevlar is. Still, some LPR rocket kits use 1/4” rubber or elastic shock cords. Those are not heat resistant.

I have a big spool of 100 pound, braided kevlar kite line I can use for shock cords. Still, I have a lot of this dacron kite line and I was hoping to use it up.

Thoughts?

 

[waltr]

If you can protect it from the HOT ejection charge then use it.

 

[brockrwood]

If you can protect it from the HOT ejection charge then use it.

Understood. But what about the rubber and elastic shock cords that come with stock kits? Those cords are not heat resistant yet the manufacturers put those cords into kits. This heavy dacron cord can’t be any worse, heat-resistant wise, than rubber or elastic, right?

I guess there is one way to find out…

 

[brockrwood]

Upon thinking this through a bit:

The rubber and elastic shock cords are usually attached near the top of the tube, a few inches below the nose cone shoulder. Those cords are protected from the worst of the hot ejection gases by the recovery wadding.

The Quest style shock cord uses a piece of kevlar to attach to the motor mount, where the hottest ejection gasses spew. The rest of the shock cord, farther up the tube, is elastic.

 

[lakeroadster]

Upon thinking this through a bit:

The rubber and elastic shock cords are usually attached near the top of the tube, a few inches below the nose cone shoulder. Those cords are protected from the worst of the hot ejection gases by the recovery wadding.

The Quest style shock cord uses a piece of kevlar to attach to the motor mount, where the hottest ejection gasses spew. The rest of the shock cord, farther up the tube, is elastic.

location... location... location

 

[brockrwood]

So, I probably could use this stuff, or any other strong polyester, nylon, or cotton cord as a shock cord as long as it is long enough and as long as it is attached near the top of the body tube and I use an adequate amount of recovery wadding.

That is my theory, anyway.

Now to test it in my next build.

 

[rharshberger]

So, I probably could use this stuff, or any other strong polyester, nylon, or cotton cord as a shock cord as long as it is long enough and as long as it is attached near the top of the body tube and I use an adequate amount of recovery wadding.

That is my theory, anyway.

Now to test it in my next build.

You can use it, as somebody else stated location..location...well you get the idea. Most of my PSII series builds 2.5", 2", and 3" use either 1/4" tubular kevlar (Wildman sourced) or good ole 550 Paracord (protected withseveral layers blue masking tape if near ejection charge point).

 

[brockrwood]

protected withseveral layers blue masking tape if near ejection charge point

Hmm. I guess I could always put blue masking tape on this cord if I use it as shock cord attached to the motor mount.

Or I could just use the kevlar for shock cords and save this stuff for flying kites! ;-). Now I need to buy a kite, as have kite line but no kite to attach it to.

 

[Scott_650]

I’ve used paracord and similar light synthetic cord as shock cord but always attached to a length of kevlar - worked fine so far

 

[Woody's Workshop]

It's slippery, so it's best attached to the engine mount, not the Estes Tea Bag Style mount. And use plenty of length as possible to avoid the dreaded ZIPPER effect! And use Tanners Bond to secure the knots! Not wood glue. You have to LOVE us Leather Crafters!
I should make a Leather Rocket! ...Someday...