advice on a repair

[rbelknap]

So, I did something dumb when I was building my BatRok. when attaching the Kevlar shock cord to the thrust ring, I set the knot with CA. :blush:

The rocket flew once and was recovered just fine, but the Kevlar broke when I was prepping the rocket for a second flight. The point of failure is (no surprise) at the thrust ring where I got CA on the kevlar, and I'm not sure of the best way to re-attach the recovery system. I'm thinking of using a bit of epoxy clay to affix the Kevlar just forward of the thrust ring.

For those tht are curious, the design of this rocket has the kevlar running out the aft of the body tube, up the outside, and back in the forward end, there the elastic and chute are housed. This allows the rocket to come down inverted, protecting the point fin tips, and helping to prevent the chute from getting tangled on the forward canards)

Right now, it's basically a desk-display model, and I'd like to fly it again.

[Rex R]

typically on mid sized birds the kevlar is epoxied to the motor tube...if it works for a 2 lb rocket, it should work for something smaller :).
rex

[bradycros]

So, I did something dumb when I was building my BatRok. when attaching the Kevlar shock cord to the thrust ring, I set the knot with CA. :blush:

The rocket flew once and was recovered just fine, but the Kevlar broke when I was prepping the rocket for a second flight. The point of failure is (no surprise) at the thrust ring where I got CA on the kevlar, and I'm not sure of the best way to re-attach the recovery system. I'm thinking of using a bit of epoxy clay to affix the Kevlar just forward of the thrust ring.

For those tht are curious, the design of this rocket has the kevlar running out the aft of the body tube, up the outside, and back in the forward end, there the elastic and chute are housed. This allows the rocket to come down inverted, protecting the point fin tips, and helping to prevent the chute from getting tangled on the forward canards)

Right now, it's basically a desk-display model, and I'd like to fly it again.




Go to: www.rocketryforum.com/showthread.php?t=33038

See post #9 by plano-doug and click on the words "draft page".

The motor retention set up could be modifiyed and used as an anchor point for the kevlar shock cord by using one t-nut.

Something like a tear drop shaped washer with two holes, one for the screw and one for the kevlar would make an anchor.

[GaryT]

If you have enough MM exposed above the CR add another CR the same way, Just don't use the CA.

[bradycros]

Go to: www.rocketryforum.com/showthread.php?t=33038

See post #9 by plano-doug and click on the words "draft page".

The motor retention set up could be modifiyed and used as an anchor point for the kevlar shock cord by using one t-nut.

Something like a tear drop shaped washer with two holes, one for the screw and one for the kevlar would make an anchor.




The washer wouldn't have to be tear droped shaped, could be any shape you want!

This type of set up would also make shock cord replaceable if it should snap again.

[bradycros]

bump.

[rbelknap]

This is a small 18mm rocket. There's no MMT, no centering rings, just a thrust ring inside the body tube. Sounds like my idea to epoxy the kevlar to the inside of the BT should work.

Thanks for the other suggestions, too. I'll keep them in mind for future rockets.