Building the Estes (clone) Fat Boy (part 1)

That Micro Fat Boy seems good. Let’s do a real one.

The Fat Boy has been out of production since 2005. Ten years gone… but not really gone; you can still find kits on eBay, for instance. Last time I checked they looked like they were selling for about $15 or so and up. Not bad at all, really. Plus shipping of course.

Then again, as I said, I have a Mega Mosquito kit I paid $8 and change for at one of the Estes holiday sales — plus shipping. The Fat Boy was a PNC-80BB nose cone, 8″ of BT-80 (slotted), 3/32″ thick fins, and an 18 mm motor mount. The Mega Mosquito is PNC-80BB, 9 5/8″ of BT-80 (slotted), fins made of 3/32″ balsa sandwiched by two 1/16″ layers, and, hm, a 24 mm motor mount.

Well, there are those who say the Fat Boy was underpowered on a C, anyway. (Let alone a B. Seriously, Estes?)

Okay then. The Mega Mo kit has everything I need for a redshifted Fat Boy, except fin material. Screen Shot 2014-10-02 at 8.14.05 PM

The fin slots are longer than needed for Fat Boy fins, but shorter than the fin roots, so should be okay.

And, you know, there’s an Estes 24 mm retainer in my stash. Use it? Use it.

The packaging used to say 325 feet altitude. OpenRocket’s telling me 475 feet on a C6-5. For the redshifted version (with 35 g nose weight), 756 feet on a D12-5 and 1171 feet on an E9-6. No Ceseroni Fs need apply; that’s enough for me. (But an E22 Smoky Sam… 991 feet, it says. Cool.)

So. I cut the body tube to 8″ length.

IMG_6179 I cut out some fins. I dithered some over what material to use but ended up with the original 3/32″ balsa. Not basswood, partly because I’m already making this heavier in the tail with the 24 mm motor mount and partly because, honestly, I didn’t have 3/32″ basswood on hand and didn’t feel like making the 5-minute drive to Michael’s for raw material.IMG_6182 But I papered the fins. Some concession to greater strength. The instructions for the Fat Boy say to leave the edges square, but I rounded the leading edges. I’m a wild and crazy guy.

I made the fin tabs a little shorter (forward to back) than for the Mega Mosquito. I marked the tab length on the slots, then transferred that distance to the motor mount tube.IMG_6187 I built the motor mount with a slanted guide straw for a replaceable Kevlar leader. For the time being I dry fit the rear centering ring, with a scrap of cardstock sporting long tabs in front of it.IMG_6188 Then I put the motor mount in, gluing it at the forward end only.IMG_6191Next I glued the fins in, one at a time using my homemade fin fixture. Evidently I had made the tabs too wide because I couldn’t get the fins in up to the root edges, so I trimmed the tabs back. I applied glue to the tabs’ root and forward edges and the fins’ root edge, but not the tabs’ rear edge. Once that was done I pulled on the cardstock tabs to remove the rear centering ring.

And was appalled.

The tabs hadn’t been too wide. Now they were too narrow; they didn’t reach the motor tube. Not only that but, despite using the fin fixture, somehow I still managed to get them in crooked. This was not a minor defect. This was a complete botch job.

I came very close to picking up a knife and cutting the fins off to start over again.

Then I heard a voice inside my head saying to take a deep breath, put the knife down, look closely at the situation, and come up with a rational plan.

Then I picked up a knife and cut the fins off to start over again. Differently. Better. Maybe tomorrow.



One thought on “Building the Estes (clone) Fat Boy (part 1)

  1. Hey, I think I just scored an original Estes Fat Boy kit on ebay and cheap!!!! I’m thinking about building it super strong with Epoxy, adding a a 29mm estes motor mount, painting it bad ass and then launching it with the mighty F-15 motors!!!

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