Big Daddy XXL - Carbon wrapped motor eating monster

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John_461

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Did you ever get that one idea that gets stuck in your head that just won't go away? And the more you think on it, the more it becomes entrenched in your mind.

I've had this idea of building an upscaled Big Daddy for over a year now, and it just wouldn't go away. So when Wildman Rocketry had a Black Friday sale, I knew my opportunity had arrived. I picked up a LOC Mega-Magg at a huge discount (THANKS @WILDMANRS !!). I went with it because it comes with a modular motor mount and the adjustable nose weight system that I wanted, and still saved money vs. buying individual components! I have plans on flying it on 54mm J/K motors at my local club launches and up to a 2-grain CTI M1560 at a bigger launch sometime in the future. And maybe throw in a 5 x 38mm cluster or 2...just for fun. Gotta love that modular motor mount system!

The plan is to replace the pre slotted 3 fin body tube with tube from LOC cut down to 26", cut my own fins out of 7-layer 3/8th" aircraft plywood from balsausa.com, and wrap it all in carbon fiber...all the coolest kids are doing it!

Should be fun!

I'll attach the .ork file below when I get home.
 
First a little background.

5 years or so ago my daughter asked me to take her out to a rocket launch that she had heard about at school. Of course I was thrilled at the idea and picked up the only suitable rocket for a respectable father to go out and fly with his kiddo. The Estes Big Daddy!

cropped 1.jpg

This one flew twice before succumbing to the Big Daddy nose separation curse and had a sub-nominal landing.

A year or two later I built another one, but this time I upgraded to some plywood fins from rocketryworks.com and a 29mm motor mount. I learned some valuable lessons along the way, and this one is still flying today.

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However...size matters...
 
Lets get this thing going!

Only one issue. I've never done any carbon or fiberglass layups before. So I obsessed over some of the build threads on this forum while I waited on parts to arrive. @Theory, @DMehalko and @kenstarr all have really good build threads, check them out...again.

I ordered a 9 inch 3K light ply sleeve from solar composites and a few feet of their 10 inch shrink tubing and got to work.

Obligatory parts pic for the Mega-Magg taken from LOC's website.

Big Daddy XXL 1-1.png

A pic with my 9 year old for size reference.

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I set up the 26" body tube on a 2" PVC pipe through the 54mm motor mount/MMAS centered in the tube to avoid any stray epoxy and then zip tied to keep the sleeve tight.

Big Daddy XXL 3.jpg

Slathered 6 pumps of West Systems 105/205 over the sleeve and dragged the shrink tube over all of that, Then proceeded to heat the tube for way longer than I expected to squish everything down. In hind sight, I think I'll do a mylar or peel ply wrap next time. The shrink tube was a major PITA and the results were somewhat mixed. Not terrible for a first attempt, but not great either. I have a few dry spots that I had to go back and lay down another bit of epoxy. But my #1 priority has been accomplished, it's very strong now. And I feel confident it'll handle whatever motors I throw in it.

Big Daddy XXL 4.jpg
 
Lets get this thing going!

Only one issue. I've never done any carbon or fiberglass layups before. So I obsessed over some of the build threads on this forum while I waited on parts to arrive. @Theory, @DMehalko and @kenstarr all have really good build threads, check them out...again.

I ordered a 9 inch 3K light ply sleeve from solar composites and a few feet of their 10 inch shrink tubing and got to work.

Obligatory parts pic for the Mega-Magg taken from LOC's website.

View attachment 569617

A pic with my 9 year old for size reference.

View attachment 569620

I set up the 26" body tube on a 2" PVC pipe through the 54mm motor mount/MMAS centered in the tube to avoid any stray epoxy and then zip tied to keep the sleeve tight.

View attachment 569618

Slathered 6 pumps of West Systems 105/205 over the sleeve and dragged the shrink tube over all of that, Then proceeded to heat the tube for way longer than I expected to squish everything down. In hind sight, I think I'll do a mylar or peel ply wrap next time. The shrink tube was a major PITA and the results were somewhat mixed. Not terrible for a first attempt, but not great either. I have a few dry spots that I had to go back and lay down another bit of epoxy. But my #1 priority has been accomplished, it's very strong now. And I feel confident it'll handle whatever motors I throw in it.

View attachment 569621


Thanks for the shout out!! Looking great and looking forward to seeing this bird come together :)
 
Did you ever get that one idea that gets stuck in your head that just won't go away? And the more you think on it, the more it becomes entrenched in your mind.
I didn't know you could hear the voices in my head

I've had this idea of building an upscaled Big Daddy for over a year now, and it just wouldn't go away.
oh! well, obviously, that's a really good idea!

this will be a great thread
 
Trimmed up the tube ends and brushed on a thin layer of epoxy to smooth over the dry spots in the initial lay up.

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And made my first attempt at vacuum bagging a carbon laminate on the aft ring of the MMAS. Once again, it’s ugly, but very strong.

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Here is a quick shot of how I kept the 7.5” body tube away from the 2” pipe.

AD7DCE92-B846-498A-B99B-AC914431C1DC.jpeg
 
Got the body tube sanded down to 400 grit today. All of the cloudiness disappears when it’s wet, so I think I’ll leave it as is until it’s assembled then I’ll take it down to 1000 grit before applying the clear coat.

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Started on the fins. I used the same process as the motor adapter base, except this time I used some quilt batting as breather material, and I made sure I held the bag nice and tight as the machine was pulling vacuum.

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I pulled the bag off at around the 5 hour mark. Everything came apart really easily and left the carbon surface just slightly rough from the porous peel ply.

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I’m pretty happy with how this turned out!
 
Lots of progress on the fins! Got the second layer of epoxy laid down on one side yesterday and the other today.

Forgot to mention in the last post that James at rocketryworks.com did an amazing job cutting these fins out for me.

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Time to cut the fin slots. I’ve read elsewhere, that this is the most nerve wracking part of the whole built. It is completely true. The first time you touch that cutting wheel to the bodywork that you’ve spent so much time on is pretty scary. But once it’s started it becomes no big deal. The one thing I wasn’t prepared for was the noise. That 7.5” tube amplified the noise to painful levels. Luckily my ear pro didn’t walk off into one of the kids rooms again and I was able to comfortably finish the job.

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I started tacking the fins down with a little bit of Bob Smith’s 5-min epoxy. And used a makeshift plumb bob and a level to verify proper alignment.

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And here is where it all went wrong…

I tacked the fins down to the 5.5” tube with Bob smith 5-min epoxy and let everything cure for around 30 min or so per fin before moving on to tack down the next one. And then I waited another hour or so before removing the fin can from the body. The fins were mounted nice and solid on the tube.

I then proceeded to add 1 pump of west 105/205 for the internal fillets. There must be something in the west systems that doesn’t play well with Bob smiths. When I poured the west systems, everything looked fine. When I came back to check on it a couple of hours later, one fin was on the floor and the other was at a very funky angle and west systems had leaked everywhere.

After lots of sanding and swearing, the damage has been fixed and everything is back on track.

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Oh and note to self. Next time don’t put the t-nut inserts in the center of the fins. It makes it really difficult to center the rail buttons.
 
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My plan is to fly this at Desert Heat Apr 1-2 so I need to get this project rolling.

Finished the internal fillets (sorry no pics…it was ugly) and mounted the Modular Motor Mount into the air frame. And locked everything down with Rocketpoxy.

I actually left the top ring off and poured 90 grams of warmed up Rocketpoxy and made sure I had a really good seal before mounting the upper centering ring and finally the aft ring.

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While all this was setting up I got going on the nose cone.

First up, a brass rod through the tip to hold in 8oz of shot with some Bob Smith 30 min epoxy for a total of roughly 10 oz in the tip. Which of course I didn’t get any pics of.
Then I moved on to a couple coats of self etching primer.

C3B86CB1-27AB-441A-A4FB-4CC68EA34B86.jpeg

While that and the body were still curing I tackled the bulkhead section of the RNWS.

I wanted to mount a Featherweight GPS tracker in the nose due to interference from the carbon in the body while still being able to use the modular nose weight system. So I came up with this.

I drilled a 1/4” pilot hole through the RNWS centering ring and the removable bulk plate then punched 1.5” hole in the centering ring.

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Then mounted the Featherweight in a sled I picked up from labratrocketey.com to the removable bulk plate and fitted the whole thing into the centering ring. And secured it with a 1/4-20 screw into a lock nut.

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Now it’s tucked away and should pick up a strong signal.

Still waiting on epoxy to cure so I went ahead and finished off the removable motor mount with a flanged 54mm Aeropack retainer.

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Fillets and nose cone prep is the name of the game today.

I like to mark my fillet lines with a piece of carbon paper and whatever tool I’m using to pull with. It’s quick easy and accurate.

In this case I used a 1.5” piece of PVC pipe.

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Then pulled 90 grams of Rocketpoxy (45g per side)

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While I waited between fillets, I continued with the nose cone. First a few coats of yellow for the tip.

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Once that cured enough to handle, I installed the RNWS, and assembled the weight slug with 16oz of shot mixed with 12 grams of 30 min epoxy.

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The hole for the tracker made pouring epoxy to seal the RNWS tube super easy. I just mixed up 10 grams of 30 min epoxy and dumped it in and rotated the nose to let it flow all the way around.

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