I've had two burn through also, both because the kevlar ran too close to the ejection gasses. Kevlar is heat resistant, not heat proof.Originally posted by sandman
I had abandoned the Estes trifold paper method of shock cord mount for the Kevlar tied to the motor mount.
I have been flying model rockets for 40 years and honestly I have never had a trifold mount break in flight.
They are easy enough to test before launch by pulling hard and easier to replace.
I have had two of the Kevlar tied to the motor mounts fail. They appeared to have been burned but I could not think of a way to replace them...so i used the Estes trifold.
This is just my obsevation and not a critisism...but i'm beginning to wonder if the Kevlar meathod is sound.
Maybe it's the brand of Kevlar.
For may trifolds I don't use regular paper. I have been using heavier card stock.
You probably would get a little abrasion/fraying on the kevlar where it rubs against the end of the tube. Of course, this usually results in a zippered tube, but if the kevlar even just got nicked a bit, that might be enough to let it break.Originally posted by Gus
Funny, I just had my first kevlar failure. Initially I thought it was a burn-through but it broke right at the point where it leaves the body tube, and looks more frayed than burned.
I've never had a trifold mount pull out of the rocket, but I HAVE had about a bazillion burn-throughs of elastic shock cords, which is why I've switched to kevlar.