Epoxying Kevlar is NOT a good idea. It gets brittle, and it *will* break eventually.

I always tie into the motor's forward closure, and I go out of my way to design my rockets to allow for that.

If that is not an option, I can show you some other options (much easier to show vs. tell in a post like this) but I would NOT use epoxy on Kevlar. it will eventually fail.

BTW, tying into the motor also is a good backup for not losing your motor...

I agree with John on this. ANY fabric webbing epoxied to the motor mount will eventually fail - usually sooner rather than later. At that point, the rocket becomes unflyable. I have a PML Io that I've been flying since before I got my L1 in 2003 and it has close to 60 flights on it all on motor ejection and the webbing below the piston is so brittle I don't think it will take another flight.

Best way is to use a eyebolt on the motor casing for reloadables or have a completely zipperless design with an eyebolt or eyenut on the zipperless bulkhead.

Warren

I planned to use an eyebolt threaded to the motor closure as a back up, but I didn't think having a single attachment point was appropriate for a large rocket.

Do it all the time on rockets considerably heavier than you can get with a 4" bird. The UprOar project (8" O-powered) used a zipperless design with a 1/2" U-bolt through the zipperless bulkhead.

That's good to know. Thanks Warren. Can you get threaded closures for the Pro54, Pro75 and Pro98 hardware?

Only the Long Burn Pro54 motors have a threaded forward closure (1/4-20) but that should not prevent you from a simple modification on your own providing you aren't using the ejection charge. The Pro 75 and Pro98 forward closures are threaded for eyebolts - 3/8-16ths

For another point to add, I have epoxied 1/4-20 eyebolts into Pro-38 ejection wells after removing the ejection charge. Rough up the inside of the plastic well with 80 grit sandpaper and they hold very well. I'm not sure you could do the same with a Pro-54. Also, I've done that on some of my AT forward closures - 29mm (need 3/16" eyebolts for that), 38mm and 54mm. I almost always fly with electronics, so it's no loss to me. I do have regular and plugged ejection wells as well.

The epoxied-in eyebolts are removable from the aluminum forward closures if you heat the closure up enough for the epoxy to start bubbling.

Warren

wow, this is an interesting thread! I have my L1 cert in my pocket and continue to feel a little gun shy on the L2.
What would really help me out is to find a willing experienced flyer who can let me pick his brain.
I am in Longmont and can bring the buttermilk, beer, or bourbon!

I am getting the 4" Nike Smoke from John and am anxious to do it by learning in advance from other people's mistakes, not by my own.
Is there anyone in Longmont who would be fine with me invading your personal VAB?

I'm in Longmont most days, be glad to shoot the shit - no need for the beer or bourbon.

I'm in Longmont as well and don't mind shating at all.

For a rocket like the Nike, you have more options - in the case above, the centering ring centers a 54mm motor in a 4" tube, so there is nearly 2" of ring to tie into. I'd probably put an eyebolt or two into that ring and consider tying into that. I didn't mention that as an option earlier, because Bret has a much larger rocket and a much smaller ring (centering a 4" tube in a 5" tube, so 1" of area to work with vs. nearly 2" for the Nike). With the Nike, you have enough room to put a washer on the backside, etc.

As far as putting anchors into CTI fwd closures... remove the delay and put a blind nut in there and lay some epoxy in there and call it good. The 54mm delays are epoxied in, so you can't remove and replace them.

8) I have a 4in. nike from John. So does Fonz down in Pueblo. We up- graded ours to 75mm and both of us have had bad ass flights with them. I used a L585 Imax that went to 11,965 at Chili Balster. If you leave it stock and build it right, your L2 should be in the bag. And a ton of other flights later. I would seek out MotoJoe for your motor selection. Maybe a large Pro 54 J or a small K. Then you can 'let-er-eat' and folks will be asking you for advise. 😛 The 4in. Nike makes it easy to HAVE FUN! I would fly that if I were you! 😀 😀 😀

I'll stand by my statement - don't glue in webbing as your shock cord anchor - regardless of the material. In a 4" bird with a 54mm motor mount you can easily use a forged eyebolt and washer or a u-bolt for the anchor point and reach in to connect the shock cord with a quick link.

Lots of options for motors as Joe, John and Tim indicate. Just remember to make sure you can reach down in to connect the shock cord. If your arm doesn't reach, put in a longer motor mount that you CAN reach - besides, it'll give you far more motor options.

I'll stand by my statement - don't glue in webbing as your shock cord anchor - regardless of the material. In a 4" bird with a 54mm motor mount you can easily use a forged eyebolt and washer or a u-bolt for the anchor point and reach in to connect the shock cord with a quick link.

Lots of options for motors as Joe, John and Tim indicate. Just remember to make sure you can reach down in to connect the shock cord. If your arm doesn't reach, put in a longer motor mount that you CAN reach - besides, it'll give you far more motor options.

To clarify - I'm not suggesting that you epoxy Kevlar - ever. In fact, I was the first one in this string to suggest it be avoided at all costs. My suggestion for an alternate attachment was to anchor an eyebolt into the upper centering ring (big washer on the back) and tie into that. In a 4" airframe, you can reach it easily.

I don't epoxy my knots, my piston strap, nuthin - epoxy + Kevlar or Nylon will fail. It becomes far too brittle and it totally changes the physical properties of the underlying fabric.