Tuesday, May 9, 2017

Estes Photon Probe #3026 Build, Part 9, Dorsal Fin Gluing

The strange thing is - The Dorsal Fins are centered on the strips. The strips aren't much wider than the 3/32" thick fins. these will be a chore to fillet and get a smooth joint during finishing.

The dorsal strip fins are set directly above the main low fins, 2 3/4" from the end of the main tube.

Instead of using a ruler to mark the dorsal positions, I made a marking guide for consistency.
The 5/8" and 2 3/8" marks are from the newer kit instructions. EDIT: As noted out in a comment, I got this wrong! The 5/8" measurement was from the top of the taper in the new instructions.

A paper strip was wrapped around the body for a consistent trailing edge position.
You'd think the larger dorsal fins would go to the rear but the smaller rectangular fins are to the back of the strips.


  1. I've just started building one of these, with a booster (I bought 31 of these when they were on sale, mostly for parts).

    The problem with having a fin jig, like I do, is that when you have to center something by eye - like the dorsal fins on the basswood strips - you kind of lose your nerve. Consequently, I've put off building this rocket for some time.

    Glad to see you're building one of these. I always check to see if you've built something before I start a new rocket, because I pick up some good tips and "Gotcha's" from you.

    1. Hi Daniel,
      You bought 31 Photon Probes? And I thought I had a build pile! They are good for parts though.
      On centering the fins - I would just do the smaller front fins by eye after using the jig for the four larger rear fins. Nobody will ever know but you! The biggest problem is trying to glue fillet the joint when there's almost no edge to apply the glue on.

    2. I bought them mostly for parts. I smacked myself in the forehead after I saw on here that you got a great stock of BT-55 parts by purchasing a bunch of clearance Monarchs. I only got one, because I thought the rocket was "okay."

      I love those PNC55 AO's, and the brown tubes that come with the Photon Probe are pretty good.

  2. I may be wrong, but I think you said in an earlier post that the original guide used 3/4" and 2 1/2" from the bottom edge of the strip. Looks like you are using the newer 5/8" and 2 3/8" marking guide, but *not* from the top of the taper. So you may be 1/8" off, but it really doesn't matter much.

    1. Hi Eero,
      You're right, I was off on the newer kit, measured from the back of the strip. I've corrected the post copy. It's not really that noticeable even with the two finished models side by side.