Hans's Mega Magg Build of Confusion

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HHaase

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I haven't started a proper build thread in quite some time, I hope people remember me.... otherwise, I hope I don't drive the newer readers away. I did another poll recently asking which build you guys wanted to see, and this was the winner. Anywhooooo..... this arrived yesterday, a shiny new LOC Precision Mega Magg. It looks like there's another build going on already so I'll try to both be different enough, and also not pull away from his. There's more than enough TRF pixels to go around. I'll also try not to pull another two year disappearance this time too.

This is my second LOC Precision kit, the other one was a 4-29SS. That build was of an older design so it didn't have a lot of the really nice things I'm already seeing in this kit. My next post will have a more detailed breakdown of everything that's part of this kit, such as the MMAS and RNWS systems. One thing is for sure, this Mega Magg is going to push my abilities in new directions. It will be, by far, the largest kit I've ever built and/or flown.

-Hans
 

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Looking forward to your build, Ill be cracking into my similar Warlock kit this weekend :)
 
Ok, color me impressed. The level of polish on this kit, compared to my 4-29SS, is light night and day..... and I really LIKE my 4-29SS. But you can definitely see the more modern development of LOC kits in the Mega Magg. The inherent versatility is fantastic. If you're not going to worry about electronics, the kit contains everything you need except adhesive, ballast, chute protector, and paint. Let's run down what we're looking at here with a first-look review.

The nose cone is blow-molded plastic with an open end, meaning it's not sealed at the base. (thumbs up!) Molding looks quite good. Strangely difficult to pick it up with my bare hands though, I just can't get a grip due to the shape, size, and texture. Anyway, the 75mm tubes and bag of bulkheads/hardware in front of the cone are for the Removable Nose Weight System (RNWS). This is a nifty looking setup that allows you to mount and remove variable slugs of weight in the nose to achieve proper stability. I've never used it before but it looks pretty straight forward and pretty similar to what I already do on my 3" nose cones for avionics bays.... just fancier and bigger.

The airframe itself is typical high quality LOC tubing, pre-slotted, with minimal spirals to worry about. The fins are laser cut from good quality plywood of a beefy thickness to be measured later. Includes a very nice parachute, proper flat-braid shock cord, and attachment hardware too. It's a single chute, no separate drogue.... like I said, the kit is designed for motor-pop recovery. TTW build, using the Modular Motor Adapter System (MMAS). Essentially the MMAS is a 5.5" body tube inside the main tube, in place of a motor mount. You're required to plug in a motor adapter depending on what you're looking to fly. Comes standard with a single 54mm motor adapter, but plenty of other options are available as standard. You can order a custom MMAS to your own design too, which is awesome.

LOC also can swap the included MMAS if you want, for a small fee, so I did! The MMAS is the mass of tubes and swiss-cheese looking set of bulkheads on the bottom-right. Rather than the single 54mm mount, I ordered an upgrade to the cluster mount. A single 54 and a half dozen 29's. I'm likely never in my life going to fly a 7 motor cluster in this thing. What I am going to do is use those 29mm tubes as utility mounts for avionics, but they're long enough I can also probably still run motors in all 6 of them too. Never know, I may completely lose my mind. Makes me glad the RNWS is included though as I'm going to have a lot of weight in the base of this thing to counter-balance.

Now, my initial thoughts aren't 100% fawning over this fantastic kit, I do have a couple relatively minor complaints. Or more accurately, just critiques to be honest. None are serious. Mostly just informational. If you're building kits at this level of performance these things shouldn't really even slow you down much.

The one I feel is most legitimate is the slots on the airframe, they're a bit narrow for the included fins. So I'm going to be doing some sanding to get clearance for things to fit smoothly. They're not off by much, in fact they're close enough I can probably force the fins through, but with the risk of wrinkling the tube. Slightly annoying but not a big deal. Just odd. I've seen it mentioned in other builds too, so be prepared for it.

The other critique is that for the level of polish on this kit, the instructions are a bit...... basic. The RNWS instructions are comprehensive, but this is not the case for the airframe and MMAS portions. Again, if you're building kits at this level you're probably not going to be concerned, but definitely expect to spend some time staring at tubes and screws while playing 'rocket puzzle' to sort things out. There's a lot of parts and little direction on how they go together. I really shouldn't complain though. I've never even received as much as a "pointy end goes up" instruction for any of my fiberglass kits. So I should be happy LOC included any instructions at all. Just seems odd to me that they put so much effort into a phenomenal quality all-inclusive kit, and the instruction sheet for the kit itself is 5 paragraphs and 3 minimally useful photos.

Overall, what's my opinion on this kit so far? I liked LOC kits before, but this is in a completely different league. Fantastic value for the money I think, with a lot of quality parts and very little else needed to make it flyable. I already asked the Wife for a 7.5 Goblin for Christmas!
 

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You’ll love the RNWS! I built up three different slugs for my 4” Phoenix, which should cover everything from the 54mm standard mount, down to the 29mm adapter I just finished for it. I also have the 38mm that it’s flown on twice already.
 
Shoot, yet another day I forgot to bring the fins into work to hit on the sander. Maybe I'll remember tomorrow.
 
Ok, let's start actually building. First step is to start destroying the 5.5" body tube by peeling off the glassine layer. This actually went pretty smooth once I got the peel started and I didn't actually destroy anything. The centering rings were sized perfect for this part of the build, as they didn't fit with the glassine layer in place and have a very nice fit to them with the glassine removed.

I also drove in the T-Nuts for the aft bulkhead, which ended up being a small problem. I did it on the concrete floor of my furnace room, and the T-nuts are a slight bit longer than the bulkhead thickness, so I mushroomed them a bit and screwed up the threads. Nothing I couldn't easily fix, just ran a tap down through them, but it was good reminder I need to pace myself and pay attention. This isn't some A8-3 rocket and I need to build things well for the energy involved.

Today was the day I remembered to bring the fins to work and use the big sander. The leading edge got rounded, and the trailing edges got a mild taper. Nothing fancy, but still enough to take away the slab-o-plywood look. I really haven't built a well polished rocket in quite some time and I'd like this one to come out nice.

I am finding, however, that a lot of areas just don't fit together well. The tab slots in the centering rings all need to be enlarged by about 1/16" or so, two of the three fin slots in the body tube need to be opened up a hair, and two of the three centering rings are also slightly over-sized for the body tube too. Strange to see fit issues this pronounced in a laser cut kit. No show-stoppers at all. Just a few small hiccups along the way.
 

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I've always found that I want to take the laser sintered edge off when possible anyway. Sometimes the burned edge closes up the pores and hurts adhesion. In this case it was about 30 minutes with a decent file to get all of these slots lined up just fine. I ran a reference line down the tube to give the location and axis for fin #1. All three fins were numbered, as are their associated slots in the bulkheads. This way I can tweak each notch to get juuuuuuust the fit that I want. Snug enough that they aren't flopping around loose, but enough of a gap that epoxy can penetrate through and won't get scraped out. Just dry fit for now, as I still need to clean up the slots in the airframe.

I also made sure the grain on these two bulkheads was not running parallel to each other. It may not be a significant weakness to have the bulkhead grains parallel, but weak points can creep up on you if they are all aligned to each other. This is how you can have failures in strange locations.
 

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Been busy building, and just dumped a bunch of photos. So I resized them and am here for an update!
Now that I had everything dry-fitted and where I thought it would line up well, I started assembling the fin can. I used my favorite epoxy for this, FlexEpox by TotalBoat. Fairly strong, soaks well into cardboard and wood grain, but it is a slow cure and slow flow. It self levels nicely and works great for internal stuff. It's also sticky as hell, stains everything it touches, and stinks. So I don't use it for external work.

Anyway, I lined up the aft ring as per the instructions (more on that later), epoxied it in place. Then the same deal with the middle ring which I lined up using all three fins and tacked in place with some medium CA glue before epoxying. So far, so good. Nice strong epoxy joints all around.

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Of course, with any epoxy, you try to pre-plan. The centering rings needed more than my normal 10cc batch size of epoxy, so every time I put a fillet onto a centering ring I used the excess to start building up the MMAS.

The MMAS is a lot of stinkin tubing. So far though everything is pretty conventional. As you can also see, I used the same epoxy for the fillets between the inner body tube and centering rings. Slow going but worked well.

Eventually I had them both assembled fully. Realistically, I actually haven't deviated from the instructions at all yet, which is unusual for me. More on THAT problem in the next post.


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I only had a little bit of FlexEpox left, so I went ahead and finished up a few other areas I wanted to use this epoxy. One of them was putting the RNWS bulkhead into the nose cone. Then there was the thrust ring in the inner body tube. I also put the bulkheads onto the man RNWS tube and the weight tube. Compared to other builds, the two holes in the RNWS bulkhead are a nice addition as they give a place for air to escape when you've sealed it all up. This is something I need to make sure to consider in a few areas on this build that I hadn't thought of yet.

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My number of parts to install is dropping rapidly. I'm also still following the instructions to the letter, I think.

The one area however that the instructions steered me wrong, but I'm not terribly upset abut, is attaching the inner body tube onto the centering rings. The exact wording is 'Slide the AFT ring on leaving 1/8" of the motor tube exposed.' I even took a picture to show how much effort I put into making sure it was exactly 1/8". I'm not too terribly worried, as this gave me exposed material to fillet both side of the centering ring. But I will have to make a spacer or something for when I mount the MMAS into here, or all the energy is going straight into the body tube. Can't trim it down either as the thrust ring is already installed.

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I only had a little bit of FlexEpox left, so I went ahead and finished up a few other areas I wanted to use this epoxy. One of them was putting the RNWS bulkhead into the nose cone. Then there was the thrust ring in the inner body tube. I also put the bulkheads onto the man RNWS tube and the weight tube. Compared to other builds, the two holes in the RNWS bulkhead are a nice addition as they give a place for air to escape when you've sealed it all up. This is something I need to make sure to consider in a few areas on this build that I hadn't thought of yet.

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My number of parts to install is dropping rapidly. I'm also still following the instructions to the letter, I think.

The one area however that the instructions steered me wrong, but I'm not terribly upset abut, is attaching the inner body tube onto the centering rings. The exact wording is 'Slide the AFT ring on leaving 1/8" of the motor tube exposed.' I even took a picture to show how much effort I put into making sure it was exactly 1/8". I'm not too terribly worried, as this gave me exposed material to fillet both side of the centering ring. But I will have to make a spacer or something for when I mount the MMAS into here, or all the energy is going straight into the body tube. Can't trim it down either as the thrust ring is already installed.

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Thanks for the photos.

50 years of calipers in my workbench tool inventory and I NEVER knew to use it as shown in your final photo!

Unbelievable. What a gap in my self-taught tool knowledge base...
 
Ok, time to start deviating from the instructions, I'm confused how I want to set up the recovery gear and I'm in the middle of typing up an email to Rocketman for some stuff. It's my first kit of this diameter, and it's not like my 3" rockets that I can just use a burrito wrap and be done with it. I need proper recovery gear, as this is the first build in a series of larger diameter projects that I'm planning.

That, and If I were to make one real change in this kit, I'd make the main recovery harness a 3-loop instead of a 2-loop.
 
I like the Y-harness's LOC offers to distribute loads, but it looks permanent, what do you do if you have to replace it? Looks like the sewn loops are in with the epoxied u bolts?
 
Yep, that's exactly the case, the y-harness is not easily removable. If I had to replace this one I'd cut it out and use quick-links to attach to the u-bolts.

Still easier than some others I've done where I epoxied it to the motor tube.

-Hans
 
LOL you're tellin me! I haven't calculated it yet. I may even make up a few different slugs based on motor usage.

Though to be honest I'm not really sure if I'll ever fly a full 7-motor cluster.
 
Do the sims now - extra MMT's you're not really going to use just make things worse. Plus, remember to plug the holes that don't have motors or you'll lose your ejection pressure.
 
I am actually going to be using most of them regularly, just not for motors. I find excess 29mm motor tubes to be super handy for avionics mounting and things of that nature. All part of the upcoming fun chapters.

-Hans
 
So, one thing I've really started doing in my last few builds, is using 29mm motor tubes as utility slots. Typically I'll do it in a nose cone, but here I've got a half dozen to work with. Even if I used a 6GXL CTI case I still have two inches of motor tube not being used for anything. I also need to worry about plugging them for when I don't have motors loaded. For half of them I'm going to put in these gizmos.
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I've used PETG for 3D printed charge wells in the past with good success. For these charge wells I was able to make the walls even beefier, and each can hold about 50grains of powder. The calculations I'm getting tell me I need half that amount.... I'll verify with testing of course. That and I need to remember to remove the motor charge when I use these tubes. It's pretty standard for me already so no big deal.

I really only need two charge wells, but I'll do three in case something makes me want another one. I have to plug these holes anyway so I might as well. I have plans for the other three, so I'll leave them open.

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I'm at a point of confusion on the recovery gear. Since there really isn't an easy way to set this up for full dual deployment, I'm looking to use my Chute Release to keep from chasing this thing across the Great Plains. I'd also like to use a deployment bag.

I'm not finding a way to make X + Y = Pineapple.

Anybody ever used a chute release with a deployment bag?

-Hans
 
OK. Take this with a grain of salt as I have never used a chute release. Could you put the main in the deployment bag, fold up the drogue and place it along the side of the bag and hold it in place with the chute release? When the chute release activates, the drogue is released which then pulls off the deployment bag. Would that work?
 
That thought is in my head for using the chute release too, I just don't know if it'll work or not. I'm also considering a few other much more complicated situations. For the first couple flights though I want to keep the deployment simple, there's just too much new stuff going into this build that I've never done before.

I'm also pushing my limits to get this thing built in openrocket. There's a lot of tubes inside of tubes, but it's all working ok I think. The main structure and the MMAS cluster are all built, and the initial motor combos I'm trying all seem to make sense for performance. A 3 grain 54mm is giving me about 3,500ft, which lines up with my expectations.

I'll also probably pull the extra tubes out in the simulation and clean it up as a single 54mm MMAS kit to match the stock configuration. This way I can get a basic version uploaded for people somewhere. The base design I found was pretty far off in a number of dimensions.
 
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Firstly, I have never used a deployment bag. Now, with that out of the way...

Depending on the design of the deployment bag you could use a JLCR to hold the bag closed until desired altitude is reached. When the JLCR releases, the drogue would pull the main out of the deployment bag.
 
Firstly, I have never used a deployment bag. Now, with that out of the way...

Depending on the design of the deployment bag you could use a JLCR to hold the bag closed until desired altitude is reached. When the JLCR releases, the drogue would pull the main out of the deployment bag.

That sounds good, but with a drogue pulling on the d-bag and the weight of the rocket trying to pull the chute out, I'm not sure a JLCR can hold the d-bag closed unless it's a pretty light weight rocket. If that's the case, just use the JLCR on the main.
 
That sounds good, but with a drogue pulling on the d-bag and the weight of the rocket trying to pull the chute out, I'm not sure a JLCR can hold the d-bag closed unless it's a pretty light weight rocket. If that's the case, just use the JLCR on the main.

That's my concern as well. It's one reason I may forego dual deploy for the first couple of flights, and then add in a tender descender instead.
 
Yes, I have but it was on a large rocket; Loc Bruiser.
It takes a little bit of though how to rig it.
The deployment bag is retained inside of the rocket till it releases.
I used to the Defy Gravity tether which predates the Tender Descender.


If you are talking about the JL chute release; you will probably have to rely on the Burrito method.


I'm at a point of confusion on the recovery gear. Since there really isn't an easy way to set this up for full dual deployment, I'm looking to use my Chute Release to keep from chasing this thing across the Great Plains. I'd also like to use a deployment bag.

I'm not finding a way to make X + Y = Pineapple.

Anybody ever used a chute release with a deployment bag?

-Hans
 
If you are talking about the JL chute release; you will probably have to rely on the Burrito method.

This I believe is the correct method when using a JLCR (Not much different then using it directly on a large main chute). I am fairly sure at least one forum member has used this method, I just cannot recall who that was...
 
I'm also considering having the chute release just keep the chute from unfurling, but still letting it fully extend coming out of the deployment bag. Either that or having the chute release hold a reefing ring. I'll be able to start laying it out on the floor soon to figure this stuff out, just waiting on a few pieces to arrive.

-Hans
 
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