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Old 05-04-2020, 07:35 PM
jgcorn jgcorn is offline
Junior Rocketeer
 
Join Date: May 2020
Location: Hamilton, OH
Posts: 1
Default Estes Trajector Construction Technique

Hello all, this is my first post here. I’m a 62 y/o BAR. I built an Estes Mammoth, one of their EX2 series. I also bought a Trajector kit, which I think is going to be a similar build. These models use E and F engines and epoxy is suggested as an adhesive. I’m not used to using epoxy as an adhesive yet. I tried when I built the Mammoth, but I ran into trouble when mounting the fins and I’m hoping to avoid this with the Trajector.

Black plastic centering rings slide onto each end of the motor mount tube. The rings have little troughs in them to accept the tabs on the fins when slid through the slots in the wall of the body tube. It was pretty straightforward to get the centering rings aligned and oriented properly and a dry fit required little sanding. But then the instructions say to smear a ring of epoxy around the inside of the body tube and quickly slide the motor mount in to its final position, making sure the aforementioned troughs are lined up under the slots in the wall. My problem arose when sliding everything into place - the little fin troughs scooped up enough epoxy which, after hardening, effectively shortened the fin “receptacle”. I didn’t anticipate this and I had to take a Dremel to everything to ultimately get the fins mounted.

I was wondering if it would be possible to introduce enough epoxy with a little brush through the back end of the tube after things are in place to effectively and safely apply internal fillets? Or is there some obvious technique of which I’m ignorant?
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Old 05-05-2020, 07:03 AM
Scott_650 Scott_650 is offline
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Join Date: Sep 2015
Posts: 624
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Here’s how I did both my Mammoths and my Trajector - build your motor mount but only epoxy the forward centering ring on the mount, leave the aft ring as a dry fit part, apply epoxy for just the forward ring in the airframe body tube, leaving the dry fit ring in place insert the motor mount, let the forward ring epoxy set thoroughly. Now you have a choice - remove the aft ring and epoxy your fins, carefully using the aft ring as an alignment tool and then epoxy in the aft ring (this technique lets you add interior fillets between the interior of the airframe/body tube and the fins), or epoxy the aft ring and fins on while skipping the interior fillets. Dry fit through these steps a couple of times until you’re comfortable - this is a typical MPR/HPR technique so a little different than maybe what you’ve done before. Good luck - those Estes E2X PSII rockets are great flyers!
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