Pemberton Technologies King Kraken

SecondRow

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I’ll start off by saying that I am not a fan of tube fins. I think they make the rocket look ugly. But Pem Tech’s King Kraken is squidlike, which makes it cool.

I ordered one from Layne last fall, but didn’t really get a chance to work on it until recently. This isn’t going to be a long build thread. Just a couple pics. There are already some good in-depth build threads on the forum, including one by @mbeels that has a great time lapse of him cutting the tube fins. https://www.rocketryforum.com/threa...g-kraken-for-level-1-cert.150845/post-1858275

Here are all the parts laid out. The main tube and the two smaller tubes have already been filled and marked. The 38mm mount, centering rings, nylon strap, chute and nose weight are standard. I replaced the 1/4” lug with rail buttons. The canards are attached to the nose cone to simulate a squid’s fins. 🦑 The 3” coupler isn’t used. Layne put it in there by mistake. I can use it as a spyglass to locate the Kraken off the starboard bow. 4B0415A6-3EB8-482B-8E98-D123512C74CF.jpeg
 
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SecondRow

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The tube fin cuts require a sharp blade, steady hand and patience, three things I never had until I had kids. The internal spirals of the tube are deeper than the external and require a decent amount of filler. I also toughened up the cut edges with thin CA, and it’s pretty obvious I made a mess of it.
62F8D4B9-D17A-4284-A243-69FC60937B5A.jpeg
I primed the tube fins before I glued them, because it would be a PITA to sand them while attached. EDF3A76F-AE2F-4DC6-9BB0-443C66AB1566.jpeg F894B429-FF89-499F-BAEB-33D0ECF18BF0.jpeg
 

SecondRow

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The nose cone is cut to allow the canards to fit in and the nose weight and canards are epoxied in. I forgot to take a pic of the nose cone cut. I tried a technique I’d read about on TRF, where you drill holes in the NC and insert a metal rod so the epoxy/nose weight mix has something to grip to. F2A464E6-86CA-4663-AF21-76C8C8BA9F9B.jpeg F9E1F451-D7D8-4CCD-BAB5-432C0643E38B.jpeg
Then trim the excess rod and sand until smooth. I used a brass rod.
 

ShadowSpire48

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How did you spray the primer inside the tubes without it running or building up on the edges? I attempted to get a nice coat inside when I did a 4” upscale but it turned out crappy.
 

SecondRow

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The rest of the build is straightforward. Glue four fins on (straight if you can). Insert motor mount with CRs and strap attached. Attach chute and connect to nose cone. The fun part is the finish. The stock kit is black with red for the tube fin internal section. But them’s U(sic)GA colors, and I’ll be damned if I ever let one of my rockets be red and black. So, I decided on purple and black to give it that monster from the deep feel.

Pem Tech has a great tip for getting the finish on the tube fins. First, you paint the inside color. Then, insert rolled up poster board in each fin and paint the external color. I was surprised at how clean the lines were. I've only got a tiny bit of overspray to fix. 23CE45F1-117C-4D32-BD78-6232A244C129.jpeg
 
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SecondRow

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How did you spray the primer inside the tubes without it running or building up on the edges? I attempted to get a nice coat inside when I did a 4” upscale but it turned out crappy.
I tried to be very careful with light mist coats but it still ran a bit. I just had to sand until smooth after.
 

SecondRow

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How did you spray the primer inside the tubes without it running or building up on the edges? I attempted to get a nice coat inside when I did a 4” upscale but it turned out crappy.
I should rephrase and say that I sanded and filled a lot to get rid of them spirals, even after the filler. Probably three or four coats of Duplicolor filler/primer. If it ran, I didn’t care because I knew I’d be sanding and filling again. Only near the end, was I extra careful. But by then I didn’t need as much primer, so I used very light coats.
 

SecondRow

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With any luck, it will fly this Saturday at our upcoming HP launch. I’d like to fly it on a Black Max or Fast Jack motor. The black smoke could look like squid ink.
 

dpower

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Nice build, I really need to get one of these (I've built the 3" Space Ark & Bucky Jones). Are the canards one or two pieces? What motor do you plan to fly it on?
 

SecondRow

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Nice build, I really need to get one of these (I've built the 3" Space Ark & Bucky Jones). Are the canards one or two pieces? What motor do you plan to fly it on?
Each canard is one piece. I'm not sure about motor, yet. Something in the G or H impulse range. I don't have any HP reload cases, only the 24/40 and 29/40-120 cases. So if I want to fly a FJ motor I'm limited to the G53, and I'm not sure just yet that will be enough thrust. Right now I'm thinking about an H115 for the first flight. It'll get me close to the dark smoke inky look I want.

Maybe it's time to buy a case. 🤔
 
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I love my Kraken. It can fly on small fields on a G80T or you can go large with a 6 grain J. I built mine using some of the build threads on TRF with an eye to durability. I intend to add an AV-Bay and payload section to make it DD capable for the larger motors. It flies at almost every launch.
 
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