Control Line: Combat
Charlie Johnson
Event rules
- Stock Voodoos (Fox .35 Stunt engines) or exact reproductions must be used.
- Minimum weight: 17 ounces.
- Lines: .015" lines (instead of .018" used in regular AMA Combat) to help keep speeds down.
- Fuel: maximum 15% nitro.
- Carburetion: venturi must remain stock size and a standard spraybar must be used.
- Contest format: most contests run at least double-elimination and use either Slow or Fast Combat rules (cuts = kills).
- Southern California event: one-minute starting period, then a four-minute match; rules for mid-airs may vary by meet (the event described here will have mid-airs not ending the match).
Construction and setup
- Aim for a model near the 17-ounce minimum. Note: some kits include heavy leading edges — in my experience over 80 Voodoos, leading edges have ranged from 1/2 to 3 ounces.
- Commercial leading edges can be lighter but usually need reinforcement at the root. If you use a bladder fuel system, the bladder tube can serve as a stiffener.
- Use the jig that comes with the kit on a flat building board and make a real effort to keep warps out of the model; bent wings ruin handling even at reduced speeds.
- Line rake: the amount shown in most kits is fine for sport flying, but with .015" lines you generally need more rake.
- Leadouts: I run the back leadout just in front of the spar and either place the front leadout about 1/2" further forward or use the same leadout guide for both.
- Tip weight: add outboard tip weight for consistent takeoffs. Start with 5–10 grams and add more if the model tends to roll or follows you out toward the handle.
- Balance and engine placement: start with the balance point shown on the plans. This will typically place the engine at least 1/2" ahead of the leading edge. Add tail weight incrementally until the model becomes touchy; that sensitivity often produces the best turning performance.
- Streamer: add a streamer for just enough stability to fly a match — if the streamer is cut off during combat, the match outcome is no worse for it.
- Avoid nose-heavy setups that force the model to plow through turns and scrub off speed; with limited power and weight, light controls and fast turns are desirable.
Engine notes
- The Fox .35 Stunt (Voodoo) engine is about two ounces lighter than the Mark IV Fox Combat engine.
- A few tuners modify headers and exhausts for easier installation and to avoid burning the wing.
- Henry Nelson's recent products have shown increased speed — revs over 28,000 have been logged using a 7x3 prop and high-nitro fuel. Expect about a 1,000 rpm drop when switching to low-nitro fuel.
- Fuel blends behave differently engine-to-engine; in some cases a 10% nitro blend ran about as hot temperature-wise as a 50% blend, indicating the importance of head shape and clearance settings.
S-36 Supertiger and other high-end engines
- The S-36 Supertiger, offered in limited numbers and modified by some tuners (for example, removing excess weight and adding AAC tuning), can be lighter than a Fox and has been run at 22,000 rpm on 50% nitro in test setups.
- Example test: a 9x6 prop cut to an 8x6 produced several hundred rpm more than a Fox .36 furnished by Myles Lawrence.
- High-end engines (in the $160 range) are generally precision-fitted and test-run; tuners like Jed log every engine produced and give fuel recommendations. They cost more but can deliver performance and consistency.
Tuning tip: Glow Bee hop-up
- Many otherwise-good engines can mysteriously lose 400–600 rpm. One simple and often effective fix is a plug change.
- Save the old plug for break-in runs or to loan out, but if an engine is lacking top-end or the plug/electrical supply is suspect, change the plug first.
- A worn plug or a weak battery can cause serious starting and running problems; when in doubt, replace the plug.
MACA Top Twenty results
- The MACA (Model Aircraft Combat Association) points are based on the four official AMA Combat events. Contests run under special rules (such as Voodoo/Fox Combat variations) are not counted toward MACA points.
- Results compiled by Tom Fluker, Sr.: Larry Driskell and Tom Fluker Jr. were at the top of the list after the King Orange meet. Larry picked up points to take the Number One spot overall. Larry won Fast, Slow, and 1/2A categories, and Tom Jr. took FAI Combat.
- If you want MACA points, fly the four AMA events; if you're flying for fun and glory, enter the variations too.
Charlie Johnson 3716 Ingraham St. San Diego, CA 92109
Transcribed from original scans by AI. Minor OCR errors may remain.
