Pathfinder build notes

The Estes Pathinder was a Skill level 3 kit, kit #1997, sold from 1988-1990.  I bought it at my local Ace Hardware store for $10.99, probably in 1999 or 2000, and left it on my shelf for 18 or more years.  The kit states you should only fly it on D engines, but I plan on modifying it to also fly with E engines (same diameter but an inch longer)

First I upgraded the 2.75” engine mount tube & D hook to 4” 24 mm E engine tube. 

Using super glue I glued on the 24 mm screw off engine retainer.  I also glued an engine block at the top of the engine mount tube.

When building the Pathfinder I decided to use my Estes fin alignment guide for the first time to attach all four fins at once.  The guide is something I bought and forgot about (it was buried in the parts box). After assembly was finished I recognized that one fin was attached a quarter inch below the other three. I decided to live with it….

It turns out that Estes included the WRONG launch lug in my kit!  I realized this after I had glued them on, so cut & scraped off the old one then attached a 3/16” lug (2”, cut in half).  Estes provided a 2.5” length of their smallest lug (1/8"?).

I coated the fins and damaged body tube where the launch lug was removed using watered down wood filler.  After it dried, I sanded the fins and body tube area smooth with 220 paper and 330 paper for the body tube, then spray paint with white primer.   I coated the inside end of lower body tube with super glue (CA) using a Q-tip per Chris Michielssen’s NAR tips then sanded the area before painting.

This rocket requires two parachutes, one for the nosecone and one for the lower body. They included the old kind where you have to cut out the parachute from a sheet, cut the shrouds, and attach each line with adhesive discs but I decided to use some newer parachutes that I had in my parts box instead of trusting myself to put the parachutes together.  It turned out I only had one available parachute so I had to build one way. I did, however, replace the pathetic rubber band they included as a shock cord with a 1/4“ x 36“ cloth & rubber shock cord and a heavier shock cord mount.  

I painted the rocket all white (Rust-oleum Gloss Enamel White), then a couple of days later painted the fins (and the lower 5”) with Rust-Oleum Gloss Enamel Carnival Red, and the upper body with Rust-Oleum Gloss Enamel Smoke Gray, with two areas taped off to leave white stripes.

The finishing touch was to apply the decals.  I reviewed some notes from Tim Van Milligan’s book, “Model rocket: Design and construction” on how to apply decals.  It’s been a couple of decades since I’ve done this, and building rockets is not “like riding a bike”.  Another good source for tips are the construction videos at Apogee Components (www.apogeerockets.com) and the summary of building tips by Hans “Chris” Michielssen on the NAR site (https://www.nar.org/educational-resources/model-rocket-building-techniques/).  Apogee also sends DVDs of their tutorial videos with each order.

My final assembled weight is 4 5/8 oz (134 gm).  1990 catalog says the weight was 3.18 oz, presumably unfinished.  The engine retainer and longer engine tube I used weigh more than the metal hook & shorter engine tube I replaced, so this will lower the projected altitudes.  OpenRocket says I should launch the  Pathfinder on either a D12-5 (603 feet) or a E9-4 (937 feet), but the original kit says 800’ on a D12 so we’ll see what happens with the modifications I made.  The Pathfinder has finally joined Larry's fleet or rockets waiting for their first launch.