L3 Project - 8" AGM-33 Pike

[Dipstick]

Mainly, it was used to align all 6 CRs and the thrust plate. It allowed me to adjust each CR by about .001" when I was lining everything up. I probably could have removed the 8-32 thread and it wouldn't have made much difference, but I do think it adds some structural support to the whole MMT and since the thrust plate is attached to all that all-thread, some of the force of the motor thrust should be dissipated through the all-thread. It should also assist in recovery by giving the upper CR some more "grip" to the rocket instead of just being held in by epoxy bonded to the airframe and motor mount tube. So, I chose to leave it in place. It is actually pretty lightweight. All that all-thread and the nuts aren't as heavy as one of the epoxy wells for the fins. And, on a rocket that is going to weigh over 75 pounds dry, I felt a few ounces wasn't going to hurt anything. Heck, the unistrut rail button assemblies are almost as heavy as the rear set of all-thread.

And, at the end of the day, this is a cert flight bird. Performance is not my goal. Overbuilt, rock solid, low and slow flight is my goal. More weight is not necessarily a bad thing in this case.

Fair enough, didn't realize it had some utility in alignment.

 

[mtnmanak]

I allowed the fin epoxy to cure overnight and then poured an 80ml epoxy dam behind the rear CR.

 

[Bat-mite]

Dam!

 

[mtnmanak]

I used JB Weld to epoxy the thrust plate in place. I mixed up a big batch of it and spread it on all the surfaces the plate will touch and used some of the JB Weld to secure the retainer screws on the back of the plate.





Once the plate was installed in the airframe, I spread more JB Weld on the all-thread and secured the plate in place with hex nuts. I put a healthy JB Weld fillet around the edge to seal it in place.





Once the JB weld was cured, I added a 100ml epoxy dam. I died the epoxy red because I plan to paint the rocket red and may as well make that process a bit easier down the road.

 

[mtnmanak]

This booster is no joke - my son is 5'2" and it makes him look small!

 

[thzero]

Some notes about the materials and parts listed above before I start the assembly photos / comments.

Nice machining... I'm certainly jealous. I just finally broke out a drill press in order to start making some custom centering rings, but that CNC router would make it so much easier/quicker and more precise.

 

[mtnmanak]

Before adding the epoxy dam in front of the forward CR, I drilled 4 evenly spaced holes around the airframe just above the forward CR using a #25 bit. I used a countersink bit to create a slight depression for the screws about half way through the frame. The screws will still be proud of the airframe on the outside, but should be seated so only the very top of the screws head protrudes. I then threaded the holes with 1 inch long #10-24 screws. I put a little epoxy in each hole and secured the #10 screws in place. They protrude inside the airframe just above the CR to provide a little more mechanical hold for the epoxy dam.








I poured a 100ml epoxy dam above the forward CR. I dyed the epoxy black to help me see any leaks and drips.

 

[mtnmanak]

Obligatory fillet portion of the build thread. I thought about skipping this post since most people are probably tired of seeing fillet posts, but in the interest of keeping this build thread "complete", I will post it.

Nothing special here. Used some charcoal on paper to mark and measure the fillet boundaries, then used angle aluminum to mark and tape the fins and tubes. Used Rocketpoxy with some red dye (same reason as above). Maybe the only real interesting point is the shear volume of Rocketpoxy you need on a build this big. All told, I used the better part of a 2-pint kit for the fillets. That somewhere around a pound of epoxy just for the fillets.

 

[Theory]

LOLz, love a solid fillet post!

those look very nice

 

[mtnmanak]

With the booster functionally complete, I reweighed the assembly and figured that the epoxy and hardware added 1,461 grams (3.2 pounds) to the booster section. The new measured CG for the booster is at 36.75” from the top of the booster tube. I entered the new information into Rocksim and re-ran all the sims.

The fillets weren't too bad, but they were so big, it was inevitable that they would have some pits, holes, uneven sides, etc. I used Bondo to smooth out the fillets and sprayed a coat of primer/filler on the joints to make any defects show up. With a bit of sanding the fillets are smooth and complete.

As a recommendation, this is another time a good random orbital sander comes in handy. I have two models. I have a Dewalt 5 inch palm sander that does great work for general purposes and relatively fine sanding. For larger jobs like this one where the main purpose is to get a lot of material off quickly, I also have a Makita 5 inch with a two hand grip. That thing really makes short work of bigger jobs. With that sander and 60 grit discs, I got most of the bondo smoothed out in about 15 minutes.

 

[mtnmanak]

The next thing I worked on was the ebay and electronics. I am using a switch bracket made of ¾” Basswood. It was CNC’ed to hold any combination of ½” switches, lights, buzzers, etc. For this build, the switch will house a switch for the main computer, a switch for the main battery, an indicator light for the main computer and a switch for the backup computer.

After drilling pilot holes in the basswood, I coated it with laminating epoxy to strengthen the bridge, then drilled the ½” holes needed for the switches and light.



The switches and lights have protrusions so, I used a Dremel to elongate the holes where necessary

 

[mtnmanak]

With the switch bracket ready, I lined up the sled and measured the end brackets for installing the metal supports.




The supports will be held in with 4-40 screws and nylon locking nuts and the sled will likewise be bolted to the metal supports.

 

[mtnmanak]

With the supports installed, I fixed the switch bracket to the sled with some 4-40 sheet metal screws:




I used the switch holes to mark out the positions on the coupler to drill the external holes.




At this point, the switch band was just held on with tape. With everything lined up, I epoxied the switch band to the coupler:

 

[mtnmanak]

I then installed all the electronics on the sled. I am using closed 9V battery cases for this build. I ripped out the case switches and soldered wires directly to the battery terminals, then secured the battery cases to the sleds with 4-40 screws and nylon lock nuts.

 

[Bat-mite]

I really want to see this launch now .... but sigh, I never go anywhere.

 

[mtnmanak]

I really want to see this launch now .... but sigh, I never go anywhere.

Well, I will have to wait until we move to Higgs field for the cert flight (can't do it at the Sod Farm), so it looks like November will be the earliest date for the cert flight - you have time to plan!

 

[mtnmanak]

Also, if the cert flight is good and we have good weather that weekend, I am hoping to turn it right around and fly it again that weekend on an AT N2220. Should be fun!

 

[Bat-mite]

Also, if the cert flight is good and we have good weather that weekend, I am hoping to turn it right around and fly it again that weekend on an AT N2220. Should be fun!

Oh, man, I didn't even realize you were an MDRA guy. Cool, then maybe I will get to see it.

 

[DaHabes]

I allowed the fin epoxy to cure overnight and then poured an 80ml epoxy dam behind the rear CR.

View attachment 474915

View attachment 474916

What epoxy do you use for your epoxy dams? I like the idea, especially for the forward centering ring which is typically hard to get at. I use Aeropoxy for internal fillets and Rocketpoxy for external fillets, but neither flow very well. Yours looks liquid enough that it pours and settles easily. I'm thinking I need a third go-to for this specific purpose. TIA.

 

[mtnmanak]

What epoxy do you use for your epoxy dams? I like the idea, especially for the forward centering ring which is typically hard to get at. I use Aeropoxy for internal fillets and Rocketpoxy for external fillets, but neither flow very well. Yours looks liquid enough that it pours and settles easily. I'm thinking I need a third go-to for this specific purpose. TIA.

I use West Systems 105/205. I think the Aeropoxy is slightly stronger (John Coker did a comparison on his site (http://jcrocket.com/adhesives and concluded Aeropoxy has the edge in strength over West), but the West Systems cures WAY faster and cures nicely at room temp. I really do love Aeropoxy and used to use it exclusively, but in the past 6 months, I have really bought into West Systems products and fillers and now most of my Aeropoxy sits on the shelf. It really is just much easier to use the West Systems product and your cure times are a fraction of Aeropoxy.

Out of the can, West Systems is a very low viscosity epoxy (much like Aeropoxy 2032/3660). Not quite water consistency, but maybe something like olive oil. With the 205 "fast" hardener, an epoxy dam like the ones I used on this rocket will harden up to the touch in about an hour at room temp. Note, they won't be fully cured at that point, but they will be hard enough for you to move on with the build.

The other nice thing about West is that the 105 Resin and the 205 or 206 Hardeners are easily available on Amazon and so are the pumps, which I highly recommend.

I use Rocketpoxy for external fillets as well, but I use West 105/205 mixed with their 406 Colloidal Silica for internal fillets. It is stronger than RocketPoxy and you can get it very thick so it stays exactly where you put it inside that fin can.

 

[mtnmanak]

The RRC3 and Stratologger computers were secured to the sled with metal 4-40 mounting hardware and everything was wired up with 24 gauge wire. The wire was secured to the sled with electrical tape. The computers were vacuum tested prior to installation.




Once the sled was complete, I drilled the holes in the switch band, ensured all the switches and light lined up and then installed the charge wells, terminal blocks and U-Bolts to the bulkheads.





I did a full system check, continuity checks and test fire of all the pyro channels. Everything worked perfectly.

 

[DaHabes]

I use West Systems 105/205. I think the Aeropoxy is slightly stronger (John Coker did a comparison on his site (http://jcrocket.com/adhesives and concluded Aeropoxy has the edge in strength over West), but the West Systems cures WAY faster and cures nicely at room temp. I really do love Aeropoxy and used to use it exclusively, but in the past 6 months, I have really bought into West Systems products and fillers and now most of my Aeropoxy sits on the shelf. It really is just much easier to use the West Systems product and your cure times are a fraction of Aeropoxy.

Out of the can, West Systems is a very low viscosity epoxy (much like Aeropoxy 2032/3660). Not quite water consistency, but maybe something like olive oil. With the 205 "fast" hardener, an epoxy dam like the ones I used on this rocket will harden up to the touch in about an hour at room temp. Note, they won't be fully cured at that point, but they will be hard enough for you to move on with the build.

The other nice thing about West is that the 105 Resin and the 205 or 206 Hardeners are easily available on Amazon and so are the pumps, which I highly recommend.

I use Rocketpoxy for external fillets as well, but I use West 105/205 mixed with their 406 Colloidal Silica for internal fillets. It is stronger than RocketPoxy and you can get it very thick so it stays exactly where you put it inside that fin can.

I looked up West Systems website and now it makes sense - it's a laminating epoxy derived for marine use. That's why it is less viscous. I'm going to add it to the tool kit for epoxy dams and as a replacement for BSI 15 & 30 minute. I'll stick with Aeropoxy for internal fillets (I always leave the back CR off to apply internal fillets, so not an issue) and Rocketpoxy for external fillets.

 

[mtnmanak]

I looked up West Systems website and now it makes sense - it's a laminating epoxy derived for marine use. That's why it is less viscous. I'm going to add it to the tool kit for epoxy dams and as a replacement for BSI 15 & 30 minute. I'll stick with Aeropoxy for internal fillets (I always leave the back CR off to apply internal fillets, so not an issue) and Rocketpoxy for external fillets.

Great plan, I think you will like the West Systems, it is a good product and very versatile.

 

[Troy3003]

I use Aeropoxy 2032 for everything, adjusting per application with either West 404 or 406 or both. I think for most cases that I will use it on strength loss from fillers won't be a factor. For me a single adhesive solution is kind of nice.

 

[DMehalko]

This build is awesome, love the documentation of everything

 

[AdAstraPerAspera]

The other nice thing about West is that the 105 Resin and the 205 or 206 Hardeners are easily available on Amazon and so are the pumps, which I highly recommend.

The West Systems pump kit comes with an odd ball pump for 3:1 mixing. That one is the correct ratio for the Aeropoxy laminating resin, and does fit the can. This is what I use when I need a thin epoxy.

 

[OverTheTop]

Nice build.

I just measure West Systems by weight. Measure hardener first, then resin. You can easily mix up just a couple of grams when needed that way. Not sure the pumps would be easy to do that with. Larger quantities are easy to mix by weight when needed too.

I am almost out of 105/206. Time to buy some more .

 

[mtnmanak]

TRF Rule #1 - every thread becomes a glue thread

The West mini-pumps come with 3 pumps. One pump goes in the 105 Resin can. The other two pumps give you either a 5:1 ratio (for 205/206 hardeners) or 3:1 (for 207/209 hardeners). So you can choose which ones you need. These pumps work great for Aeropoxy 2032 as well and I use the West 3:1 pumps for my Aeropoxy cans.

The nice thing about the pumps is that they work great whether you want to use them as intended or if you are going to measure by weight. One full pump of Resin and Hardener gives you 20ml of epoxy. So, if you need multiples of 20ml, just use the pumps and forget about it. But I also use the pumps for measuring by weight because the pumps are precise enough to deliver just one drop at a time, so it is easy to put the cup on my scale and dole out exactly the amount of resin and hardener I need. I used to put the resin and hardeners in squeeze bottles, but the pumps just make it so much easier.

Either way, all the epoxies mentioned are wonderful products - you can't go wrong with any of them.

 

[mtnmanak]

Getting close to finished with this build. Got the shear pins for the booster drilled and tapped today. Only major build item left is the nosecone/nosecone ebay. Going to try and power through that part tomorrow so, hopefully, I can start painting it this weekend. I am hoping to be ready for a shakeout flight in two weeks on an L2500 or L2200. I may just prime it for that flight and do the finish paint later. We'll see how much time I have.




I also installed 6-32 Lumadyne PEM nuts in the payload bay to hold the ebay into the upper section.

 

[rfjustin]

Getting close to finished with this build. Got the shear pins for the booster drilled and tapped today. Only major build item left is the nosecone/nosecone ebay. Going to try and power through that part tomorrow so, hopefully, I can start painting it this weekend. I am hoping to be ready for a shakeout flight in two weeks on an L2500 or L2200. I may just prime it for that flight and do the finish paint later. We'll see how much time I have.

View attachment 477027
View attachment 477028

I also installed 6-32 Lumadyne PEM nuts in the payload bay to hold the ebay into the upper section.

View attachment 477030

Some of your custom made tooling makes me so very angry. And by angry I mean jealous!

Looking like a tank, looking good!