4" custom Iris build

I painted the main section on Christmas Day, then removed tape and vinyl lettering while video chatting with family that lives in a much colder climate:

I finished masking the lower section and prayed for another good painting day. Just a few days later the temperature and humidity got just within acceptable ranges in the afternoon and I finished up the paint job:

Remember those 4-40 socket cap screws? They could go back in and stay, now:




I also ran to Lowe's and got the pieces to make myself a rocket cradle:

Well, that about sums everything up for now. My biggest hurdles are mostly financial as I still need parachutes, a second altimeter, and a motor. In the meantime I am working on finishing up my avionics bay. I'll post pictures of that once it's further along.

That looks fantastic, thanks for sharing! Have you flown it yet?

Edit: I missed the last post, so you've already answered my question.

You weren't kidding when you said you started this rocket "a long time ago..." at last months meeting.
Looks like its been a good learning process. Decided what you want to fly this on first?

I'm curious about your choice to do shear pins on the booster.
(and have you though about brass strips inside the tube? cardboard doesn't shear them as well as fiberglass I've heard)

Wow! This has turned out to be an incredible build, and fantastic detail, great work!

Nytrunner said:

You weren't kidding when you said you started this rocket "a long time ago..." at last months meeting.
Looks like its been a good learning process. Decided what you want to fly this on first?

I'm curious about your choice to do shear pins on the booster.
(and have you though about brass strips inside the tube? cardboard doesn't shear them as well as fiberglass I've heard)

Click to expand...

I'm not sure exactly what you mean about the brass strips, but I'm open to other ideas if it's something I can still implement. I settled on the 2-56 nylon screws based on the advice of some other club members. I did pour some CA through the holes and then redrill them for a little extra strength, but I recognize that even flexible phenolic tubing won't hold up like that forever. If I make it to the February club meeting you can tell me more there (and you'll have to remind me who you are as I really haven't gotten to know folks yet).

Oh, and I think I'll probably be flying it on the highest thrust 'I' motor I can find as a first flight because I'll need to recertify. I didn't keep my TRA membership up after I got Level 1 the first time.

BigBlueDart said:

Oh, and I think I'll probably be flying it on the highest thrust 'I' motor I can find as a first flight because I'll need to recertify. I didn't keep my TRA membership up after I got Level 1 the first time.

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I am in the same situation with Tripoli. The people who make the rules don't consider the hassle and money it costs, as it's no money out of their pocket.

Your rocket turned out very nice.

Where did you get the scale info? I would like to pick up a copy! Tim Thomas L3

BigBlueDart said:

I'm not sure exactly what you mean about the brass strips, but I'm open to other ideas if it's something I can still implement. I settled on the 2-56 nylon screws based on the advice of some other club members. I did pour some CA through the holes and then redrill them for a little extra strength, but I recognize that even flexible phenolic tubing won't hold up like that forever. If I make it to the February club meeting you can tell me more there (and you'll have to remind me who you are as I really haven't gotten to know folks yet).

Click to expand...

Will do! I may even have an extra strip if you want to experiment with it.

I'm the tall guy.

BigBlueDart said:

All this was going on over the course of the Spring. After that I entered another phase where I got busy in life and/or the weather wasn't good for painting. But at some point in the middle of everything posted above I also started working on my avionics bay:

And yes, I know that last picture of the back of my sled is hideous. This is my first avionics bay, so I'll likely look at some other designs and work on something more elegant for future builds.

Click to expand...

Looks good. I'll make a few comments here and there. First. You should probably change out you eye bolts with closed eye bolts. Either cast or if those aren't stainless, weld them closed. You don't want them to pull open. It can happen...
Regarding the bulkhead cover over the motor mount; you realize that limits the length motor you can install, right? Hopefully, you left enough space to fit a CTI 54mm 6XL case in there, or the new AT 54/2800. That K990DM for the 54/2800 is awesome!

BigBlueDart said:

Well, that about sums everything up for now. My biggest hurdles are mostly financial as I still need parachutes, a second altimeter, and a motor. In the meantime I am working on finishing up my avionics bay. I'll post pictures of that once it's further along.

Click to expand...

Nytrunner said:

You weren't kidding when you said you started this rocket "a long time ago..." at last months meeting.
Looks like its been a good learning process. Decided what you want to fly this on first?

I'm curious about your choice to do shear pins on the booster.
(and have you though about brass strips inside the tube? cardboard doesn't shear them as well as fiberglass I've heard)

Click to expand...

BigBlueDart said:

I'm not sure exactly what you mean about the brass strips, but I'm open to other ideas if it's something I can still implement. I settled on the 2-56 nylon screws based on the advice of some other club members. I did pour some CA through the holes and then redrill them for a little extra strength, but I recognize that even flexible phenolic tubing won't hold up like that forever.

Click to expand...

Regarding the brass strips for shear pin cutting. Here's what I did with mine built out of the same material (flexible phenolic). I bought 1/2" wide brass strips from HobbyTown. They have different thicknesses. I don't remember which thickness exactly. I think I used .015". Cut pieces 1/2"x1/2". Mark their location on the body tube inner surface. Cut down 1 layer of tube and peel it out. Cut as many layers out until the brass strips are flush with the inner surface of the body tube. Do the same for the outer surface of the couplers. If you drilled the holes first, perfect. Epoxy the brass strips into the recesses. Then realign the body over the coupler and redrill the holes through the brass. Viola! Instant shear pin shears. The plastic shoulder of my nosecone was a more difficult challenge, but basically the same process, just with a dremel and sanding drum instead of peeling layers. I use three 1/16" styrene rods for mine on both ends. Stuff it in the hole and snip off the rod. When I run out of styrene rods, I'll switch to 2-56 nylon screws.
Hope this helps.
Adrian

jd2cylman said:

Regarding the brass strips for shear pin cutting. Here's what I did with mine built out of the same material (flexible phenolic). I bought 1/2" wide brass strips from HobbyTown. They have different thicknesses. I don't remember which thickness exactly. I think I used .015". Cut pieces 1/2"x1/2". Mark their location on the body tube inner surface. Cut down 1 layer of tube and peel it out. Cut as many layers out until the brass strips are flush with the inner surface of the body tube. Do the same for the outer surface of the couplers. If you drilled the holes first, perfect. Epoxy the brass strips into the recesses. Then realign the body over the coupler and redrill the holes through the brass. Viola! Instant shear pin shears. The plastic shoulder of my nosecone was a more difficult challenge, but basically the same process, just with a dremel and sanding drum instead of peeling layers. I use three 1/16" styrene rods for mine on both ends. Stuff it in the hole and snip off the rod. When I run out of styrene rods, I'll switch to 2-56 nylon screws.
Hope this helps.
Adrian

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Thats more experience than I could give you. Its probably something that can be done at any point during construction.
I've also found the strips at Lowes in the 'Specialty' drawers of the bolts aisle.

jd2cylman said:

Looks good. I'll make a few comments here and there. First. You should probably change out you eye bolts with closed eye bolts. Either cast or if those aren't stainless, weld them closed. You don't want them to pull open. It can happen...
Regarding the bulkhead cover over the motor mount; you realize that limits the length motor you can install, right? Hopefully, you left enough space to fit a CTI 54mm 6XL case in there, or the new AT 54/2800. That K990DM for the 54/2800 is awesome!







Regarding the brass strips for shear pin cutting. Here's what I did with mine built out of the same material (flexible phenolic). I bought 1/2" wide brass strips from HobbyTown. They have different thicknesses. I don't remember which thickness exactly. I think I used .015". Cut pieces 1/2"x1/2". Mark their location on the body tube inner surface. Cut down 1 layer of tube and peel it out. Cut as many layers out until the brass strips are flush with the inner surface of the body tube. Do the same for the outer surface of the couplers. If you drilled the holes first, perfect. Epoxy the brass strips into the recesses. Then realign the body over the coupler and redrill the holes through the brass. Viola! Instant shear pin shears. The plastic shoulder of my nosecone was a more difficult challenge, but basically the same process, just with a dremel and sanding drum instead of peeling layers. I use three 1/16" styrene rods for mine on both ends. Stuff it in the hole and snip off the rod. When I run out of styrene rods, I'll switch to 2-56 nylon screws.
Hope this helps.
Adrian

Click to expand...

Thanks for the tips. I actually already have the eyebolts anchored in with epoxy. I might be able to dremel it off, though. Not sure if I'll do that or just consider this yet another lesson learned for next time. And yes, I am aware of how the bulkhead is limiting my motor size. I'm stuck with a maximum 5 grain motor, but I'm sure to build some more 54mm rockets eventually with full length MMT's.

I think I kind of get what you're saying with the brass strips. I'll likely wait until somebody in my club can show me before trying it, though.

BigBlueDart said:

Oh, and I think I'll probably be flying it on the highest thrust 'I' motor I can find as a first flight because I'll need to recertify. I didn't keep my TRA membership up after I got Level 1 the first time.

Click to expand...

I'll suggest the CTI 38mm 5 grain I540!

Or the AT 54/426 I599N. 170 lbs of thrust off the pad... .7 sec burn... Don't blink! Or the AT 38/720 I600R. 182lbs thrust off the pad, and a smidge longer burn...

BigBlueDart said:

The joint between my main body tube and the fin can section had a bit of a gap due to unevenly cutting the body tube. I decided to try fixing this by filling it in a bit with epoxy and filler. I wrapped the coupler in plastic wrap and then slid the body tube over it. Then I pulled the plastic back up and filled in the gap. The plastic protected the main body tube and kept the pieces from getting stuck. The result wasn't perfect, but it was much improved:

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Neat trick, especially if/when a rotary sander isn't available. I'm very pleased you decided to update this thread - it's a very cool build and I love the attention to detail.

Nice pictures, thanks

Very nice build!

Tim51 said:

Neat trick, especially if/when a rotary sander isn't available. I'm very pleased you decided to update this thread - it's a very cool build and I love the attention to detail.

Click to expand...

No need for fancy tools for that. Wrap a standard piece of paper around tube and tape in place, then draw a line at the edge that needs trued up. Then just use a block of wood and sandpaper and sand to the line. Just takes a few minutes, super simple.

Thanks for coming back to this build thread and continuing the build for us. Nice looking rocket and great detail.

-brant

Oh man, what a build. Excellent job man! I'd buy one of these in kit form no doubt .

Oh yes, what brand of nose cone is that? PML?

Killer build, great job!

Binder Design said:

No need for fancy tools for that. Wrap a standard piece of paper around tube and tape in place, then draw a line at the edge that needs trued up. Then just use a block of wood and sandpaper and sand to the line. Just takes a few minutes, super simple.

Click to expand...

Thanks Mike - I'll give that a try next time.

pyrobob said:

Oh yes, what brand of nose cone is that? PML?

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Actually, I think it was a Pinnacle nosecone sold by Giant Leap Rocketry. This build has been going on so long I'm forgetting details like that, but pretty sure I got the majority of my initial materials from them.

The IRIS will always have a place in my fleet. Absolutely EXCELLENT build!!!

LOC said:

The IRIS will always have a place in my fleet. Absolutely EXCELLENT build!!!

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One of my rocketry regrets, was not getting your Yank 5.5" IRIS when I got the 4" one. Silly me, I thought one IRIS was enough... Please tell me you might bring back a flexible phenolic 5.5 IRIS again.

jd2cylman said:

One of my rocketry regrets, was not getting your Yank 5.5" IRIS when I got the 4" one. Silly me, I thought one IRIS was enough... Please tell me you might bring back a flexible phenolic 5.5 IRIS again.

Click to expand...

Yo Adrian,

The 5.5" flex phenolic Iris is the Rockets For Schools Class II rocket...I get to fondle new 5.5" Irises every year. Bet Dave can get one to you!