Ringmasters Flying Club

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Old School VooDoo Combat

So one day I told Steve Muller that I had a couple of old Fox combat motors, a .35X and a .36X.  I said I was thinking of making a VooDoo and Steve said he had a .36X as well as some VooDoo plans. Perfect !!  I made a few copies of Steve’s plans and set out to construct an old school VooDoo with a bit of newer materials and methods.

First things first, a fuel tank.  I made up a quick CAD drawing of the tank I wanted keeping in mind the constraints of the wing where it will fit.  I fashioned a tank body and a couple of tank ends from .005” Brass sheet.  Next I inserted the feed and vent lines.  Since I planned to tap the motor for crankcase pressure I soldered up the end of the vent line and then drilled a small orifice hole through the solder.  Then I buttoned up the tank with solder all around and pressure tested the unit.

The wing is a simple barn door with 11 wing ribs and 4 center ribs that are only slightly different due to the planking on the center section.  I slotted the leading edge and then dry fitted the wing before gluing it up and then mounted the bell crank and fuel tank into their places.  Next I made up the center motor mount from ½” Maple with a balsa filler and 4-40 blind T-Nuts.  I fashioned a motor mount cheek from ½” balsa and epoxied it all together into the wing.  The two booms are made from 1/8” plywood and the elevator is 1/8” balsa.  The motor mount, booms and elevator are the only painted parts.

After some assembly I had a bit of instant gratitude as I feel is necessary during any build.  Final assembly consisted of mounting a piece of 1/8” tubing to the front of the elevator with some Tyvek and then gluing it all together to the wing.  After mounting a clevis to the pushrod and control horn, the only thing left was to mount the motor.

The motor is a sweet old Fox .35X that has the rear plate tapped with a fitting for crankcase pressure and the venturi insert drilled out slightly for more airflow to allow for the pressurized fuel feed.  With a Zinger 7.5 x 7 prop it makes almost 84 mph.  Not bad for a 50+ year old design.

Mike Geroir