Scratch - Phoenix Downscale {Scratch} Original Design / Scratch Built

Contributed by Chris Halinaty

Manufacturer: Scratch
(Contributed - by Chris Halinaty - 08/31/08) (Scratch) Phoenix Downscale

This is a 40% Phoenix downscale based on Estes kit #1380.

The parts list:

  • ST10 body tube (9")
  • BC1032 nose cone
  • #7 to #10 engine mount
  • 3/32" fin stock
  • Kevlar® shock cord (30")
  • Copper coated steel BBs for nose weight
  • 14" parachute

All the parts I used for this project were ordered from Semroc. I chose the Phoenix as my downscale for the 2008 EMRR Challenge because of the availability of the nose cone and body tube size. The Semroc ST10 is almost exactly 40% of the diameter of the regular Phoenix body tube and the BC1032 nose is an exact match.

This was a fairly easy build. I followed the instructions for the regular Phoenix, which I downloaded from JimZ, with the following exceptions:

  • I used a single body tube instead of two pieces because the shorter length of this downscale did not require using two.
  • I attached a Kevlar® shock cord to the motor mount instead of the Estes-style folded paper with rubber shock cord.
  • I did not shape the fins because of their small size.

Tracing a fin pattern and cutting it was more of a challenge than I anticipated. I did get better as I went and I think after some sanding, the fins turned out how I wanted them.

I used RockSim to check the design of this downscale Phoenix and found that it needed some extra nose weight. I drilled out part of the nose and epoxied about 12g of BBs into it. The rocket is a little heavy but should be stable even with an Estes C6 engine.

I used Krylon white primer and gloss white top coat to finish the Phoenix. For decals, I downscaled the regular Phoenix set and printed them on my HP inkjet printer using Avery clear label sheets. This method worked out great, although once a decal is on, it is almost impossible to reposition, so a few of mine are a little crooked. Still, this is an easy, inexpensive method for putting that finishing touch on any rocket.

The Phoenix Downscale (40%) simmed fine on RockSim using Estes A8-3, B6-4, and C6-5 engines. I flew it twice using an A8-3 and once with a B6-4. All flights were good, although it seemed to spin a little on the way up using the B6-4.

This rocket recovered well using a Custom Sam-X 14" parachute. It received a slight zipper (1mm long) on the first flight, so a small piece of tape was added around the Kevlar® shock cord and its second and third flights were fine. Because of the nose weight and the slight angle I had to launch it from, it tended to deploy with its nose down but put pretty much at apogee each flight.

I loved the challenges of building this rocket. It is a simple design, but it looks great, especially with the many decals from the original kit.

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