My L3 Build

[thzero]

Finally started this year my L3 build, after discussion with TAP for design, and various other L3 mentors. So after collecting a bunch of pictures, of the build process, etc. I'd thought I'd toss some out just for fun. I'll eventually post the L3 document to the L3 thread.

Anways, using a Wildman 5" Drago as the rocket and planning to send it up on a M1297 but leaving room to shove a N2000 in some time in the future.



I'll note that this is not my build documentation or thread, just some photos, etc. I found interesting.

 

[thzero]

Following the technique I used with a 3" build and then used in two 4" builds, I am using internal fin guides to help lock the fins in place. In a way this is similar to the LOC and/or Apogee fin lock systems with their plywood centering rings, but using 3D printing (why not?!)

The write up on the 3" build that uses them. My 4" Mac Performance was build using same techniques, then same techniques used again with a custom 4" Wildman rocket.
https://www.rocketryforum.com/threads/3-mac-performance-modified-zodiac.176554/

I don't know that this is any easier or harder than other techniques. But when you get everything correctly lined up, and fitted, things just slide into place and that for whatever reason is just satisfying.

First cut of the fin guide. It went through a few integrations to end up at the final version that I used. Final version has a built in captured nut for bolting in the bottom rail button. And also has 3 captured nuts for bolting in the SCP aluminum thrust plate (because why not?).



Basically the finished bottom guide. Top guide is very similar, but without the captured nuts. Oh I should say everything is printed on a BambuLabs X1 Carbon and using their PET-CF filament (not PET*g* mind you) on a .4mm nozzle.




You can clearly see the fin slots. The slots pointing the opposite way are slots for the sidewalls to form the glue dam for the fin pocket. They worked ok. The point was to help keep the sidewalls all aligned, straight, etc. when glueing them down.

A shot showing both the fin guides and the sidewalls taped into place with the fins.

 

[thzero]

Side jaunt. Using SCPs airfoil shaped rail guides. No particular reason other than they caught my eye. They are not 3d printed, in case anyone is asking, probably delrin and/or nylon blend. Anyways, wanted to use #10 stainless steel bolts instead of the 1/4" bolt and so created 3d printed adapter sleeve.

 

[thzero]

Ok... the fin guides and sidewalls on the 98mm motor tube, which doesn't leave a lot of room in a 5" rocket. A shout out to @cwbullet as he had suggested in another thread about using square nuts instead of hex nuts. Less chance of them spinning. So all the captured nuts are square nuts, and then JBWelded into their captured pockets.



Everything looks real good. Then I shoved it into the tube itself (no pics here) to test the alignment with the fin cutouts from Wildman, and everything lined up great with only some minor file work! A beautiful thing.

Another shot of it.



And with the fins taped in.



JBWeld was used to attach both fin guides.



Finished with sidewalls installed. The bottom of the sidewall was glued to the motor mount with CA epoxy. Then you can see where I've started to rough up the epoxy dam surface.

 

[troj]

Your fin attachment rings/centering rings are an interesting idea! I really like the idea of including the nut in them for attaching the rail guides.

I'm curious - your first post shows an OpenRocket/Rocksim side view with the motor in it. Is that the planned design? If so, is that long enough for the 98/15360 case?

Looks like a nice project!

-Kevin

 

[thzero]

Mounted using Aeropoxy ES6209 epoxy. It was not particularly runny, so not real fillers needed which in this case is good IMO, but yet was able to form a nice filet as it set and cured. Basically measurements were done and marked with tape at the bottom and top of the booster tube where the epoxy should go. Using a light down the tube, with fiberglass it makes it easy to see where to epoxy. Then I added a nice thick ring of epoxy about .5" thick around the tube where the top fin guide/centering ring goes. Then slide the motor mount in part way, and then another nice thick ring of epoxy for the bottom fin guide.

Then just slid the component all the way in, and make sure that all the fins were aligned. This is really important! Then set it off to cure. Note the fins are just in to help make sure everything cures straight. I occasionally pulled them out to make sure nothing was leaking anywhere and accidently curing to the fin.



I didn't think about it before hand, but I really should have created a nice stand that braced the booster tube and motor mount since there is a over hang for the thrust plate in the exact position I wanted them. So I had to jury ring something and carefully watch it.

The other lesson learned is that for the captured nuts that bolt the thrust plate on, make sure to have some sort of roof to avoid any potential epoxy leaks going down the threads. Others have suggested using grease, etc, but er, I don't want grease on my threads.

Using an endoscope, I examined the filets the ES6209 made as it settled, I like it.

 

[thzero]

Fins are the ones that came with the kit, they are quite beefy. Only adjusted them slightly to drill some holes allowing the epoxy from the epoxy fin dams to flow through the fin (or so theory goes).



Afterwards.

 

[thzero]

Fins are attached by shoving them in the fin pocket/dam that has been filled with epoxy. HTR-212AF epoxy with cut fiberglass was used - magic formula was 4 teaspoons of cut fiberglass to 1 oz of resin, and .33oz of hardener.



Then I degassed it using a vacuum pump.



Video of the degassing in progress, coolio.
https://photos.app.goo.gl/8GddTm6qo15e6Puc9

 

[thzero]

The epoxy was poured into a big syringe



Then injected into the fin pocket/dam. The catheter based end was a bit too big to fit into the slot, but it still worked out.



Epoxy filling the fin pocket! Then the appropriate fin, that was adjusted if needed for that pocket, was just slide into place like it was building Legos!



A 3D printed fin guide was added just as an extra step with a small shim in each of the other two fin pockets. This was printed out of PLA and was pretty much pointless.

Curing took place in a hotbox oven that my buddy biodragen constructed and let me borrow for a couple of my rockets.



Fins cured in 30 minutes or less! Well at least the initial cure was, then they'll fully cure like most epoxies over the next 24-72 hours. This was cured at 150F. I didn't take pictures of them, but um, PLA sucks in heat, and sure enough they just melted.

 

[thzero]

Action shot?!



Fins attached and ready for filets!

 

[thzero]

Your fin attachment rings/centering rings are an interesting idea! I really like the idea of including the nut in them for attaching the rail guides.

I'm curious - your first post shows an OpenRocket/Rocksim side view with the motor in it. Is that the planned design? If so, is that long enough for the 98/15360 case?

Looks like a nice project!

-Kevin

Yeah.. its a N2000 shoved in there which I checked OR vs Aerotech drawings and should be all the right size. The booster is a 60" booster from Wildman that comes with the kit.
Certainly know the case for the M1297 fit because I got the tech drawings from Aerotech, printed out me a version using couplers and test fit in my 4" rocket which only has 48" booster and will run the same case. Then my buddy let me borrow his case for a test fit!

 

[thzero]

A random tool! This was a 3d printed end for a 1/4" aluminum rod that I can attach sandpaper too. It was used for sanding all the interior surfaces my arms wouldn't reach to! Was used more in my 4" build just because of the smaller diameter, 5" allowed me to shove more of my arm into it.



Another tool. Squaring jig. Didn't have a shot of 5" version, so this is 4" version. It worked ok. But it worked better when combined with the wrapping a stiff piece of paper around the tube method. Now things mate flush!

 

[thzero]

The 3D electronics stack for the trackers. There will be three trackers on this bird. The Featherweight GPS tracker here in the nose cone. Then two Marshall trackers, one attached to the main parachute shock chord, and the other attacked to the booster stage.

Anwyays, this bolts to a fiberglass bulkhead that contains the upper attachment u-bolt for the nose cone. Then that bulkhead is bolted into the nose cone. It'll work my 4" and up builds.

 

[thzero]

Filets. Well, my RocketPoxy is nearly gone, and it doesn't seem that there is much of a chance of it coming back. So what to use? Epoxy thread!!

Anyways, I tried some HTR-212AF mixed with milled/cut fiberglass and silica (think it was 4 teaspoons of fiberglass and two of silica) for a somewhat smooth and thick paste. It worked well mostly to spread, and held its form. Did it in the heatbox, so didn't really get a chance during the leather stage to smooth it out more. May have helped? Anyways, they came out well, but require crap load of sanding. So ok, learned something.






Felt like I was in a Rocket Vlogs video!! Sanding, and sanding and more sanding... no wait more sanding! Still note done, have to sand some more.

So ok, having done that. What else? Looked around and since I was already using Aeropoxy and they have the ES6279 which I've seen mentioned before, and I have a local (ish) Aircraft Spruce I picked some up (not exactly that easy to obtain, had to wait a bit).

I know others such as @jd2cylman have had good luck with West Systems 610 on large rockets, I decided to do a bit of test. See this post for the results for 610 on his 6" punisher build.

https://www.rocketryforum.com/threads/rocketpoxy-availability.170138/page-9#post-2596890

Anyways my small write up is here.

https://www.rocketryforum.com/threads/rocketpoxy-availability.170138/page-9#post-2597935

Anyways going with the ES6279 which had good results for flow, etc. in my small test.

 

[cwbullet]

Fascinating bid that shows the way to mix composites with 3d printing. Thanks for staring.

 

[ECayemberg]

Build is looking fantastic! Truly enjoying the sharing of your L3 Build; thanks for posting!!!

 

[Theory]

Very cool!!!

 

[troj]

A random tool! This was a 3d printed end for a 1/4" aluminum rod that I can attach sandpaper too. It was used for sanding all the interior surfaces my arms wouldn't reach to! Was used more in my 4" build just because of the smaller diameter, 5" allowed me to shove more of my arm into it.

I love the way you're combining 3D printing to build tools, jigs, alignment bits, etc.

I need this tool. Can I bribe you to make one for me?

-Kevin

 

[thzero]

I love the way you're combining 3D printing to build tools, jigs, alignment bits, etc.

I need this tool. Can I bribe you to make one for me?

-Kevin

Well I did post the sanding tools over on Cults3D,
https://cults3d.com/en/3d-model/game/rocket-sanding-tools
And also just posted the squaring tool
https://cults3d.com/en/3d-model/game/rocket-tube-squaring-tool

 

[thzero]

Grade school tool for marking filet lines on the rocket. Rub some graphite from a pencil on a piece of paper, use your filet tool of choice and....



Lines... Faint but they work. Even on the black fiberglass fins it was enough that the graphite would reflect that I could see where the marks were.

 

[thzero]

Some more mostly simple tools.

3d printed guide for the switch band with the holes in for the altimeter as well as the Pull Before Flight flags. Also made it convenient to help true up the tubing for a nice fit.



And then some bolt drill guides for the nose cone's centering ring and bulkhead that allow the tracker bay to be installed into the nose cone.





And the 1.5" diameter filet tool. Didn't have something of that radius as I scrounged around the house, so just printed one!

 

[Hobie1dog]

great 3D printing

 

[thzero]

Taping up for doing filets.


Filets are almost done using the Aeropoxy ES6279. Came out pretty well, not perfect but close enough with a bit of sanding should be good to go. To me ES6279 is a bit sticker, and maybe tad thicker, than Rocketpoxy. That and I hadn't worked with this much of Rocketpoxy either previously, so may totally a apples to apples comparison, but overall got them done and they settled pretty nice. I didn't end up using the hot box on them, but they were pretty much in a shape that I could move on and do another set in about 40 minutes.

 

[thzero]

Getting ready to drill out the various holes in the switch band. So there is a tool for that.






Then taped up so it doesn't move around on me.

 

[thzero]

Well, slightly change on the above as I always struggle with getting clean drill hole with the fiberglass tubes. Putting a backing behind it seems to help



So the general procedure these days is to do a starter hole, that does not quite go through. Then switch to a brad point drill bit with medium pressure, just enough to let the tool do the work. Between the pressure and the backing, we get reasonably clean holes. If need be I will take a diamond drill bit and do some clean up.

 

[KenECoyote]

Well, slightly change on the above as I always struggle with getting clean drill hole with the fiberglass tubes. Putting a backing behind it seems to help.

Are you using regular drill bits? I find using them along with a regular hand drill for pilot holes is too rough and imprecise for rocket tubes. I like using a Dremel with their 1/8" drill bit and it drills the starter hole at a high speed, which is much more controlled, cleaner and neater. I'll then use the regular drill bits and hand drill to enlarge the hole. Ymmv

Quite a fantastic and meticulous build!

 

[thzero]

Are you using regular drill bits? I find using them along with a regular hand drill for pilot holes is too rough and imprecise for rocket tubes. I like using a Dremel with their 1/8" drill bit and it drills the starter hole at a high speed, which is much more controlled, cleaner and neater. I'll then use the regular drill bits and hand drill to enlarge the hole. Ymmv

Yeah I've been using regular drill bits. But the diamond bits are generally done with a dremel. Hadn't thought of doing pilot holes with the dremel, nice suggestion.

 

[thzero]

Quite a fantastic and meticulous build!

Thanks! It probably appears more meticulous than it may be...

 

[thzero]

One thing I like to do is treat my fiberglass tube cut ends just like I do carboard, thin layer of CA around the lip soaks into the fiberglass tube and seals the cut ends. Then smooth the surfaces and round off the inner surfaces slightly if they are sliding together

 

[thzero]

RunCam6 mount that will eventually be used. I had printed this version for someone, so mine will probably be in PET-CF with a layer of HTR-212 epoxy then painting.