Let's see, to address your questions:

1) I love the EZI65, my favorite LOC kit. A very good choice.

2) Aeropack retainers are the sine qua non of motor retainers in my opinion. While I've only used the 54mm and 98mm sizes, I would highly recommend them for any size.

3) For a shock cord mount, I would probably use a steel cable from the forward centering ring to a ring a couple inches inside the airframe and then use a Quicklink to attach it to a Kevlar or nylon shock cord connecting to the recovery harness and nose cone. The EZI is a great sport rocket and if you want lots and lots of flights, don't glue in a nylon shock cord to the centering ring - it won't last more than a few dozen flights in my experience.

4) For filler for the body tube spirals, I would use Elmer's wood filler. Lightweight, easy to sand and takes paint and primer well. For fin fillets, I would mix my epoxy with silica microballoons or similar epoxy filler. Lay out tape on both the body tube and fin, make little dams at the front and rear of the fin and pour in the epoxy and let it level out. When it cures, all you need to do is pull the tape and do a bit of sanding and you're done with great fillets.

Good luck with your L1.

Warren

Thanks for the opinion on the Aeropack retainers.

As for the shock cord mount, this method you are describing sounds a lot like the old north coast rocketry Gorilla shock mounts. My only concern is that the kevlar or nylon you suggest may not be elastic. What does this do for shock loads during recovery deployment?

Elmer's wood filler. Wow I would not have guessed that it would stick or be resiliant enough.

Thanks. I remember from my former rocketry days that the membership in a good club was a make or break thing. The advise from others who have been there done that is most helpful.

I'd been looking for a good club, and this is the best I've ever seen, due to the members and the launch sites. First thing, forget model rockets (but as many people fly those in our club, so don’t forget them completely). While the same physics apply, the same construction techniques do not! Trust me on that one. I won't tell you how many times it took me to get just the L1, I can feel a lot of my friends smiling now and shaking their heads. The thing that defeated me every time was construction. And, I made just about every mistake you can make. In the end, it was good, 'cause the higher in certs you go, the more expensive it gets. Having the model rocket “shock” cord stuck in my mind threw me, too. As our president of our club would say, "Keep the elastic in your underwear; don’t use it in high power." I use a Kevlar "harness" instead of nylon because it's about as fire proof and strong as you can get, you could tow your car or truck with it (plus one of my L1 failures was a burned and severed nylon cord... though some of the biggest rockets use nylon, e.g., Event Horizon, a 365 pound rocket used a two inch nylon harness). Just make sure it's long enough. You need to time the ejection charge and keep the harness long enough to absorb the shock. You'll get a good idea on how to do things at the next launch. As a side note, a friend and I were helping with certifications at our last big event, Mile High Mayhem, and one of the people said she and her husband belonged to a model airplane club, and NO ONE in that club would lend anything or help you out. The down side of this club is having people tripping over each other trying to help you out. Welcome!

I actually just achieved my L1 at MHM. This is a really great group, and they are really helpful, and the launch sites are excellent.

In terms of length for kevlar/nylon shock cords, a general rule of thumb is 3 to 5 times the length of the rocket. Personally, my comfort level is a harness with 4x the length of the body tube being outside the rocket, as long as there's room in the body to hold it. That shouldn't be a problem with the EZI. Kevlar is definitely a good way to go, another option I like is to use kevlar inside the body, and nylon outside, keeping the nylon wrapped in a chute protector. Modular is definitely the most important part, and if you take Warren's advice of using steel cable, either material will serve you well. If you're particularly worried about issues at deployment time, you might use a piece of high density foam where the harness exits the body tube, this will provide some cushion at that point, and provide decent protection from zippering. There are a ton of options, as I'm sure you'll discover, but certainly for L1 KISS is a very applicable principle.

Welcome (back), and good luck!

I got my L1 a couple years ago with a LOC Fantom EXL (about the same as the EZI, but 38mm instead of 54). I used about 25' of GLR's tubular kevlar and the only problem (on a later flight) was a bad zipper on an early deployment. The GLR fireball wasn't enough to stop it. I haven't done a motor deploy since!

Good luck, have fun, ask questions! This is a great club and VERY active.

Ken

Thanks for all the info folks. I assume that if I run a steel line from the forward centering ring this is done by drilling 2 holes in the wooden ring then looping the steel line though the holes and securing the loop with a crimp. Do you place anything between the loop and the wood of the centering ring to keep the steel loop from cutting through the wood?

I looked at the GLR fireball and thought this might be a cool idea. I will likely use a kevlar shock cord and chute protection. Again thanks for the advise guys.

For the harness anchor, I used a U-bolt (from Home Depot) with the steel back plate. It's a bit heavier, but it's not going anywhere. You have a bit less room to work with since you've got the 54mm mount, though. The 4" airframe is roomy enough to reach in and attach/detach the quicklink to the kevlar.

Ken