Apogee Zephyr L1 Build

[Alan R]

This thread is just to document the build for L1.
Nothing special about the build, but I already know I will deviate from instructions in one or two places. Nothing major.
Kit arrived yesterday.. I'm excited to jump in.

When I decided to L1, I wanted a 38mm and I had a couple of kits in mind. LOC IV, Zephyr, possibly a Patriot.

I wanted a big rocket (4"), and something that looked a little different from the rest of my collection.

I chose the Zephyr because it's a more complete kit than the LOC IV, great value for the money, and I didn't need to buy anything extra. Plus it just looks pretty cool.

Unboxed with my JLCR which arrived at the same time

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[ThirstyBarbarian]

I’ve seen a few of these flying at local clubs, and they seem like great rockets. Nice size, uncomplicated build, solid, good looking, complete kits, and a good value. Everyone seems happy with them.

 

[AfterBurners]

I’ve seen a few of these flying at local clubs, and they seem like great rockets. Nice size, uncomplicated build, solid, good looking, complete kits, and a good value. Everyone seems happy with them.

they need a better recovery harness though. I'm not to big on what they give you. If it had loops sewn on each end that would be better

 

[Alan R]

they need a better recovery harness though. I'm not to big on what they give you. If it had loops sewn on each end that would be better

The harness hookup is one of those minor deviations I'm going to make. I'll probably put a quick link on the eye bolt and a foot or so of kevlar onto that. Then I'll connect the included harness.

 

[Alan R]

solid, good looking, complete kits, and a good value.

That's what really sold me on this one. Hard to find a complete kit at this price ($89) where you don't have to add on a bunch of extras.
I did order $30 of extra items to go with it: a LOC 38/29 adapter and an aerotech retainer. Neither of those things are required to fly, they will just make it a bit easier.

 

[ThirstyBarbarian]

That's what really sold me on this one. Hard to find a complete kit at this price ($89) where you don't have to add on a bunch of extras.
I did order $30 of extra items to go with it: a LOC 38/29 adapter and an aerotech retainer. Neither of those things are required to fly, they will just make it a bit easier.

The retainer will be a nice upgrade. The included one seems adequate but inconvenient. And the adapter will be necessary for 29mm motors and will open up a lot of motor choices.

 

[Alan R]

And the adapter will be necessary for 29mm motors and will open up a lot of motor choices.

Exactly. I know my cert flight will be on an H 38mm, but when I was looking at motors I noticed that almost all Aerotech G motors are 29mm. It's going to need a couple of test flights before I put in that H.

 

[Alan R]

First update, and first deviation from instructions.
I have a bunch of 100# Kevlar for my low power stuff. It's a little light for this so I braided a 6-strand leader on the quick link and put a bowline on the other end. About 2' long, short enough not to zipper. I can always lower the loop if I need.

This lets me move the shock cord to another rocket if I want. Just reach in and take out the quick link.

Dry fit of MMT with shock cord attachment.

 

[Speaknoevil]

Looks like a nice kit!

 

[Dougla2]

Have you considered doing a test of your leader design? There is a protective tube to slide over the nylon cord available. I worry that the Al fastener modification that I made, and component tested, isn't quite up to the robustness of the original simple design. Great design and parts, hope to see a flight in a few more weeks here. I used wood glue to attach the tubes and had the easy slide seize up halfway, so I slammed the end down on the table, forcing them together and smushing the end slightly. The video shows using epoxy to avoid that problem, so blame goes here for not following the instructions. Enjoy building it!

 

[ThirstyBarbarian]

Exactly. I know my cert flight will be on an H 38mm, but when I was looking at motors I noticed that almost all Aerotech G motors are 29mm. It's going to need a couple of test flights before I put in that H.

Sounds like a good plan. You would need to do some sims with your final build weight but I would guess any of the higher-thrust single-use Aerotech G motors with a short delay would give you a nice low test flight. Motors like the G77-4, G78-4, G79-4, and G80-4 come to mind and should pop it up around 500 to 700 feet. That’s perfect for observing the flight, including the deployment and recovery. You can put a little altimeter in there too if you like and check if the flight matches your sims.

One thing you might want to check is whether the included ejection charge in a single-use G has enough powder to deploy the recovery system. I’m not sure how much volume you have inside the rocket or the exact amount of powder in those single-use motors.

 

[Alan R]

You would need to do some sims with your final build weight but I would guess any of the higher-thrust single-use Aerotech G motors with a short delay would give you a nice low test flight. Motors like the G77-4, G78-4, G79-4, and G80-4 come to mind and should pop it up around 500 to 700 feet.

I sim'd the zephyr file I downloaded from Apogee. The G79W says 730', the G80 at 1000. Either of those would make a good test flight. That would be a perfect stock build, so I would expect it to fall a hair short of those numbers.

I'll get my motors on site from the vendor, so depends on what he has.

OTOH.. might want to plan ahead just in case. Plenty of time for shipping right now.

 

[Alan R]

Have you considered doing a test of your leader design? There is a protective tube to slide over the nylon cord available. I worry that the Al fastener modification that I made, and component tested, isn't quite up to the robustness of the original simple design. Great design and parts, hope to see a flight in a few more weeks here.

Testing my leader design... the only difference here is the quicklink. I use kevlar leaders on my 24 and 29mm birds. Those are mounted through the MMT, out the back, and tied around the motor tube. But that light kevlar line (doubled) has never caused a problem.

I'm aware of the sleeve. There was a video that showed somebody just wrapping the nylon line with duct tape for a couple of feet. But I've got 500' of kevlar string, might as well use it.

 

[jackman]

Be sure to add a dab of epoxy or Loctite to the eybolt and nut to prevent it from unscrewing itself. It appears to have a lock washer but I always use the belt and suspenders approach.

 

[Alan R]

Be sure to add a dab of epoxy or Loctite to the eybolt and nut to prevent it from unscrewing itself. It appears to have a lock washer but I always use the belt and suspenders approach.

Epoxy on the eyebolt is in the instructions, and I'll do it when I glue that first centering ring.

 

[Alan R]

Another nice thing about this kit: the instructions are thorough and really detailed. Kudos to Apogee for that.

 

[ThirstyBarbarian]

Does the motor tube extend that far above the forward centering ring? Are you going to be able to get your hand in there to work the quick link?

 

[Alan R]

Does the motor tube extend that far above the forward centering ring? Are you going to be able to get your hand in there to work the quick link?

Darn you. Darn you to heck. I had to go try it. Just dry fitted the mmt and NOPE.. that body tube is about 3' long and my arm isn't going down in there.

Looks like it will be a permanent rig, unless I can modify my old sink wrench.

 

[ThirstyBarbarian]

Darn you. Darn you to heck. I had to go try it. Just dry fitted the mmt and NOPE.. that body tube is about 3' long and my arm isn't going down in there.

Looks like it will be a permanent rig, unless I can modify my old sink wrench.

You can still use a Kevlar leader. Tie it permanently to the eyebolt. Put a loop at the other end. Use the quick link to attach the nylon cord to the loop in the leader. Just be sure you are confident that the leader is a strong permanent part that you won’t need to replace.

I wonder why the motor tube is that long? You could probably just cut enough of it off to be able to reach the quick link. It’s ok for a motor to extend beyond the motor tube.

EDIT: My suggestions are assuming it’s not already glued in. If it is glued in, then it is what it is. No big deal.

 

[Alan R]

You can still use a Kevlar leader. Tie it permanently to the eyebolt. Put a loop at the other end. Use the quick link to attach the nylon cord to the loop in the leader. Just be sure you are confident that the leader is a strong permanent part that you won’t need to replace.

I wonder why the motor tube is that long?

I braided the kevlar directly onto the quick link, so it's going to have to stay there. No big deal. I have to believe that if one strand is 100 lb rated, then 6 strands will be at least 500 lbs. It has a loop on the other end for attaching the nylon cord, almost as good as a quick link.

If there ever is a problem with the leader, I suppose it will be possible to replace that quick link, but like I said ... I may have to rig a sink wrench to do it.

The motor tube itself is only about 1' long, I guess for those larger H, I motors. It's the length of the bt that makes reaching it a problem, not the motor tube.

 

[ThirstyBarbarian]

I braided the kevlar directly onto the quick link, so it's going to have to stay there. No big deal. I have to believe that if one strand is 100 lb rated, then 6 strands will be at least 500 lbs. It has a loop on the other end for attaching the nylon cord, almost as good as a quick link.

If there ever is a problem with the leader, I suppose it will be possible to replace that quick link, but like I said ... I may have to rig a sink wrench to do it.

The motor tube itself is only about 1' long, I guess for those larger H, I motors. It's the length of the bt that makes reaching it a problem, not the motor tube.

Ah, Ok. I misread your earlier post and didn’t get that it was the length of the BT that was the problem. This isn’t a big deal.

 

[Alan R]

Cool trick by apogee. Spacers for the CR's to match the fins. Weave the little cord around the aft CR, so you can pull it out easy for gluing fins.
I always do the epoxy for TTW fins by removing the aft CR. Wish I'd known about this trick before. I think I just used a screw eye.
Forward CR and eye bolt epoxied.

 

[Dale Medin]

I am just a little ahead of you. Started doing the fin fillets last night. Using rocketpoxy and some micro balloons.
So far I have done 2 fillets and they came out really well. Hoping the other 4 go just as well.

 

[Alan R]

I am just a little ahead of you. Started doing the fin fillets last night. Using rocketpoxy and some micro balloons.

Cool! Keep up the good work. We shall compare test flights in a few months!

 

[Alan R]

Don't have a fin jig that fits 1/4" ply. I'll print one while I round off leading edges.

 

[Cmac]

I built the same kit for my L1 and LOVED it! Once the zombie apocalypse is over and my club starts flying again, I might actually get to send it up.

they need a better recovery harness though. I'm not to big on what they give you. If it had loops sewn on each end that would be better

I agree. I brought mine into a seamstress and had him put a loop in each end and one 1/3rd the distance in for my chute.
With the attention to detail that I've noticed from Mr. Van Milligan, I'm surprised he let this one go.

Are you going to be able to get your hand in there to work the quick link?

Darn you. Darn you to heck. I had to go try it. Just dry fitted the mmt and NOPE.. that body tube is about 3' long and my arm isn't going down in there.

Looks like it will be a permanent rig, unless I can modify my old sink wrench.

Check this idea out. I used it and am very happy with it.
https://www.rocketryforum.com/threads/the-u-loop-shock-cord-attachment-method.137445/

 

[Alan R]

Check this idea out. I used it and am very happy with it.
https://www.rocketryforum.com/threads/the-u-loop-shock-cord-attachment-method.137445/

Oh that's a nice way to rig it. Sometimes I think I'm so clever I completely miss these simple solutions.

Done. That still gives me 8-9" of Kevlar in front of the motor tube. Thanks for the tip.

 

[Cmac]

Thanks for the tip.

You're welcome but if you stole it from me then it's been stolen at least twice.
Blind-leading-the-blind warning: Don't miss the whole idea that the design it meant to be able to replace the shock cord in the future.
In order to do that, you'll have to be able to attach one end of the new shock cord to one end of the old shock cord.
That's the way my inexperience has me understanding this anyway.
I made mine long enough to come up to about 4 inches below the the top of the BT.

 

[Alan R]

Don't miss the whole idea that the design it meant to be able to replace the shock cord in the future.
In order to do that, you'll have to be able to attach one end of the new shock cord to one end of the old shock cord.

Moving that quick link up 9" should make that doable in the future if I need to. If I'd known about this before I would have braided another foot of leader, but this will work just fine.

 

[Cmac]

Good luck on your L1.