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LOC Precision Norad Pro Maxx Build

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DrewW

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Level 1 certification flight is tomorrow on a PML AMRAAM3, but I couldn't wait and ended up starting my next HPR build.

I was checking out the LOC website a couple weeks back and noticed the Norad Pro Maxx had been discontinued this summer, but ended up seeing one elsewhere online I couldn't pass up on. I was going to try and fly it as a backup rocket for tomorrow but as fate would have it the kit was missing two pieced. Thankfully the folks over at LOC have awesome customer service and in about 5 minutes had a package ready to ship with my missing pieces.

Did some dry fitting and ready over the instructions and decided to make a few changes as I go through. First, instead of the ginormous launch lug, I decided to use some rail buttons since that will work better with my local club launches. Second, I decided to modify the set up to anchor the shock cord on the centering rings rather than the tube wall.

First step in was filling spirals...first time I've ever gone through the effort but planning to make this one pretty. Used some Elmer's putty, let it dry, and got it all sanded smooth. With the Arizona humidity back down to ~10% it didn't take much time.

Spirals filled.png

Next I got the forward centering ring epoxied onto the motor tube and realized as I was positioning it that, I'd nearly let the epoxy set filling the pre cut notches, that would have complicated my plan to adjust the shock cord, but luckily I realized my mistake before the epoxy had gelled and was able to clean it up pretty easily. With the forward CR filleted I loaded up the transition piece and taped it to the CR to hold it out of the way.

While checking out measurements and going through some dry fitting I realized both the mid and aft CRs would need to be sanded down quite a bit for a fit in the 3" lower body tube. While I was spending some quality time sanding and making repeated dry fits I realized this was also the right time to put on my rail buttons. Unfortunately, my rail buttons have a rather tall weld nut and weren't a great option for the thin walled lower body tube so I dug through some of my spare parts and came up with a 1010 lug and, having seen it in TRF before, decided I would cut it in half and mount With the arrangement I have I'll end up using a some epoxy to mount to the tube and run a screw through retained by a nut on the inner wall.

1010 Launch Lug.png
Split Lug fitting.png


Because of the very long motor tube on the rocket and the three CRs this means I need to get these set before I mount the next CR because I wont have access to the top lug inside the tube after mounting. It also means that I need to accommodate the retaining nut with the CR. So after a lot of sanding to fit the rings I took one over to my drill press to put in a couple holes for eye bolts and also to remove some material for a notch to clear the nut. then cleaned it up with a bench chisel and only a little sanding.

Centering ring notch.png

At this point it was getting pretty late and I realized I didn't have small enough eye bolts to mount so I called it a night before making plans to stop at the local ace hardware in the near future.
 

DrewW

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Level 1 certification flight went perfectly last weekend, but after launching on an AT H283 (boy was that fast burning) and being within 5% of projections there wasn't a chance to load the AT I218 to try and double the altitude. Oh well, two more weeks to the next launch.

Anyway, lots done on the Norad Pro Maxx this week and just not enough time left to make any posts tracking progress so here I go...

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Launch lugs were epoxied in place and threaded through with a #4 screw and a nut securing each inside the tube, and enough epoxy on the nuts to lock them in place. Because of the modifications I had made for the shock cord (time will tell if I did this well enough) I had two eye bolts run through the mid body centering ring opposite each other with a nut and washer on either face to try and distribute the load. Initially I epoxied the hole, each washer and nut but there was still a little play in the nuts on the threads. I followed up with some extra thin CA on the threads and in a few seconds after wicking the bolts and nuts were solidly joined. Mid body centering ring was epoxied to the motor mount and then transition was taped to the forward CR to give some clearance while installing into the 3" aft body tube. before going further I cut a generous amount of 200# kevlar shock cord made an attachment loop and fed down through the forward CR notches and tied off on the eyebolts.

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As I was dry fitting the motor mount I realized there wasn't enough space to properly fillet the forward side of the mid-CR so I ended up doing a little flood filling with some slow-cure epoxy to try and get as much grab as possible and at the same time set the transition to the body tube. After curing I came at the mid-CR again from the aft and did a better job of getting a fillet. Again, my modification to the shock cord changed the plan, instead of epoxying the first of two 2.1" forward body tubes I drilled for #4 screws so I could access the shock cord loop in the future. There really isn't a lot of left over space in this rocket.

Next up the payload section. I upgraded the self tapping tiny eye bolt with a more substantial 3/16" eye bolt also using a washer and a nut on each face for strength, and also a dab of CA to lock the threads, then mounted the bulkhead in the end of the coupler.

IMG_8798.JPG


Then called it a night and let everything cure for a couple days.
 

DrewW

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Next up I went through and dry fit the fins to make sure everything was looking good.

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Then followed instructions rounding the leading and trailing edges and sanding the faces smooth. Rounding that 1/4" birch plywood, was tedious but happy with the results. I initially mounted up the fins using a plumb line as a guide and some medium CA to give a few moments to lock in a good position. Rotate and repeat.

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After the fins were tacked I used some 30 minute epoxy to secure internal fin fillets making sure to use slow enough epoxy to fill as many cracks as possible; but because the area is so tight I grabbed a few oral syringes and some 1/4" tubing cut to an appropriate length to deliver the epoxy without a whole lot of mess.

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Results weren't beautiful, but they will serve.

Here I decided to order an aeropack motor retainer...oddly most of my go to vendors were all out of the 38mm L (and only this retainer) which I needed so I ended up in a holding pattern. I also decided to get some RocketPoxy, another item out of stock at most of the places I normally look. So while waiting for those items to show up in the next couple days I went ahead and taped out the external surface for epoxy.

IMG_8815.JPG
 

Tyler P

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The build is looking good! I always liked the look of that kit. Nice form to it.
 

DrewW

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A little unexpected, but my aeropack motor retainer showed up early and my RocketPoxy from Apogee is late... both USPS, go figure. BTW, very happy with Chris' Rocket Supply.

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Anyway, after trimming my significant excess tape off the aft section with a hobby knife, I did a dry fit to make sure I had clearances figured out correctly for the aft centering ring and the motor retainer and then promptly realized I hadn't put any tape or other contrivances on the aft CR to be able to pull it back off, oops. thankfully my set of picks fit in the gap behind the fins and were just long enough to use the curved picks to lever the CR back out from the inside. Only minor damage to the CR from the picks and all on the inside nobody will ever see.

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Afterwards I put down a line below the motor retainer to be my reference for epoxy. This time I mixed up some 15 minute epoxy and spread around the inside of the 3" body tube and got about setting my aft CR in place with about 1/8" of relief and set the lower section aft side down to try and let the epoxy get the best adhesion it could on my schedule tonight.

After giving time for the epoxy to set up, I mixed up another small batch and laid down a fillet on both the motor tube joint and the body tube joint, being careful to stay below my retainer reference line. Then I set aft end up to again get the best wicking and contact possible.

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While this was setting up, I took some course emery cloth to the internal surface of the motor retainer and then scuffed up the motor tube pretty well, gave a wipe, and after making sure the epoxy had set hard enough I mixed up some JB Weld and buttered up the motor retainer and motor tube.

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I got a little overzealous with the JB Weld and after giving 30 minutes or so to just let it finish squeezing out where it may and getting the slightest amount of set up, I came along the inside wall of the motor tube with my hobby knife and cleaned up the excess JB Weld, then came through and smoothed up the external JB Weld fillet.

Hopefully the RocketPoxy shows up in the next day or two and I can put the finishing touches on the build so I have a few days for the paint before our next launch on Nov 7th. Thankfully living in Arizona with ~10% humidity means I can lay down a fair number of coats each day to make it pretty...or at least bright/shiny; after consulting with my 7 year old daughter, we've agreed to a pretty obnoxious color scheme mostly because grass and green things aren't a problem locally. Yellow nosecone, bright green upper and fins, with a glossy metallic silver lower.

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Looking at an AT I140W DMS for the maiden flight with a simulated apogee of ~3650 ft, chute release at 300 ft, bringing total time aloft to right about 120s.
 

DrewW

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Well crud, USPS appears to have lost my RocketPoxy package from Apogee (no fault to Apogee). Any recommendations for epoxy from hardware stores? Otherwise I'll be cutting this rather close. I was hoping for something with better setup properties than BJI 30 minute which doesn't have much of a working period for smoothing and shaping in the gel phase.
 

Banzai88

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A lot of folks like West with colloidal silica. Haven't tried it myself, but I may soon, as I have 3 13" long fins to fillet and am looking for something lighter than my usual go to of 4500.
 

Tyler P

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BSI 30-minute and micro balloons are what I use on mine.
 
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