15th April 2012, 11:15 PM
Executioner Clone Build
The Estes Executioner has been discontinued from the 2012 catalog. You can still find these kits in the retail channel, but they will dry up eventually. Thankfully this is an easy kit to clone inexpensively.
Another good reason for a scratch or clone build is that you can modify anything you want to get the desired end result.
I have an Executioner clone which is starting to show it's age. It has a few dents in the balsa nose cone, a couple of marks from "almost-zippers", and two of the fins have been re-attached with rather liberal amounts of 5-minute epoxy.
Since I already have all the necessary parts and pieces in my "parts bin", the time is ripe for a new clone. Besides, it's Sunday, and It's raining... no other excuses needed.
Plans for the kit can be found on the JimZ website at
The plans are .pdf and include a full size fin template. Which is helpful.
I use OpenRocket
along with the plans and the rocksim file found at EMMR Rocket Reviews.
The rocksim file is very close with the fin template. I'll be tweaking the file in OpenRocket to match my build.
Fin templates print right from OpenRocket after I adjust the fin tabs for my build.
With my clone I'm planning to modify the original design to include:
- A zipperless/baffle mid-break design.
- Launch Lugs and Rail buttons
- Screw-on motor retention
- Kevlar shock cord
- Nylon chute
- TLAR precision cloning methods as needed.
*TLAR "That Looks About Right"
15th April 2012, 11:21 PM
I decided to use a 24mm motor tube, rather than upgrade to 29mm. I have a bunch of 24mm motors to use and not enough 24mm rockets. This will be a reasonably light build and flies nice with the 24/40 case and reloads. There is always the Pro24 line from CTI if I feel the need to push it into *LEO.
Nose cones can be sourced from Semroc, Balsa Machining Service, or this guy on eBay. The eBay one is plastic, and thatís the one I chose to use this time.
The nose cone gets a quick skim-trim with the hobby knife to remove any excess flashing. A shaving/scraping motion with the hobby knife really makes those mold seams disappear. Then a quick wash and dry to remove any silicone mold release or other contaminants. I use a green (coarse) Scotch Brite pad in the wash to take off the "shine" and prep the plastic to accept paint better.
*LEO "Low Earth Orbit"
16th April 2012, 02:36 AM
A few holes are drilled in the side of the nose cone shoulder to aid with a more "mechanical" bond to the airframe since glue won't stick to the plastic very well by itself. All holes were carefully drilled with "tlar" precision measurement.
Two holes are drilled in the base for the shock cord. I also scuffed-up the shoulder of the cone with some 80 grit paper for better glue adhesion. It won't show, so it doesn't need to be pretty.
At this point I measure and weigh the nose cone and adjust the .ork sim file accordingly. Even though tlar will be used in the build, I want the sim to be reasonably accurate.
I'm using about 3x the length of the rocket for the shock cord. 9-10 feet or about 3 meters, tlar again. Kevlar can be hard to cut. I use a utility knife with a sharp blade.
Tie an overhand loop in one end of the shock cord. This will be the loop that later connects via quick link to the baffle. Measure about 1/3rd (one meter maybe) from the end loop and make another overhand loop in the shock cord. This is the loop for the chute. Now fold up the shock cord into a neat bundle and wrap it with a small rubber band. Toss it on the scale to get the weight for the sim.
16th April 2012, 03:06 AM
On a recent order I threw an executioner in the mix, I didn't know it was going oop. Glad I did!
I'm excited to see what you have in store for your clone, hopefully I can shamelessly steal some ideas from you!
16th April 2012, 05:19 AM
Every good cloner has to a a good set of tools and reference material. In addition to the Plans at JimZ's, I found this to be an invaluable help.
The Estes Body Tube List has the two BT80 airframe tubes at 14.2 inches each. Total airframe length 28.4 inches.
I'm using Hobbylinc SureFire BT-80 tubes that are 15 inches long. I trimmed an inch and a half from one tube to get 28.5 inches total for the two tubes and called it "tlar".
The Estes Tube Marking Guide set has a little adjustable stop that works like a depth gauge for marking the cut line.
To make neat straight cuts, I measure and mark a line where the cut should be, then wrap a couple turns of painters masking tape around the tube at the line. The tape acts like a guide for the knife.
Green painters tape - not too sticky, no damage to the tube, and cheaper than the name brand blue stuff.
It also matches the color of the cutting mat (bonus points)
Z is for Zirconium.
Load a NEW blade in the hobby knife and make several 8-12 or more passes around the tube with the point of the knife. Work slowly and use the tape edge as a guide.
Peel the tape off and "de-burr" the cut edge with a sanding dowel. (Just a piece of scrap dowel with sandpaper CA'd on one end.) The sanding dowel is used to rough up the inside of the tube so the glue will adhere better. Toss the tube on the scale, and adjust the sim weight as needed.
Everything used in the build with the exception of glue and paint gets weighed. I like to get the most from the sim in OpenRocket - It is a great tool.
I'm trying to think metric when it comes to rocketry. I weigh things in grams, and have OpenRocket set for metric measurments.
Science is mostly metric, and rocketry is my excuse to think and work in the metric system.
16th April 2012, 05:26 AM