RADIO CONTROL PYLON RACING
Duane Gall 1267 S. Beeler Ct., Denver CO 80231 E-mail: stinger4@earthlink.net
A TOTAL FAI Lure, Part 1:
Descend with me into the depths of insanity—into a Pylon event known by many Europeans, but by only a handful of Americans. This is "primal-scream Pylon," the "ultimate Pylon," "Pylon with no apologies and (almost) no-holds-barred."
Unlike Quickie 500, F3D—as the event is code-named by the Fédération Aéronautique Internationale (the Paris-based sanctioning body for full-scale and model aviation competitions)—was never intended as an "entry-level" event, and has never been marketed for that purpose.
F3D has everything the late, great Formula I had, and more:
- sleek five-pound airplanes going nearly 200 mph
- tuned exhaust systems
- reworked engines
- homemade propellers
- even retractable landing gear, for those who dare
The only thing it doesn't have is nitromethane.
You heard me right—not a drop of nitro is allowed in F3D. The Europeans write the rules for this event, and not only does gasoline go for much more there, but nitro is all but impossible to find at any price. On the theory that allowing nitro would give too much advantage to the rich and well connected (and therefore depress attendance at contests), the rule-writers prohibited it from the very beginning.
Do F3D contestants whine about having this element "taken away" from them? Do they daydream about how much faster they "should" be going, if not for the cruel tyranny of those socialist killjoys on the rules committee? No. They make do with competing against each other according to the agreed rules, because this is what competitors do.
Even with this handicap, F3D fans manage well. The fastest maintain roughly a one-minute pace—fractionally quicker than the best Quarter 40s, using the same engine displacement and an airplane that weighs nearly a pound more. The secret is the tuned pipe. It begins to resonate at the magic rpm, acting like a supercharger, but with no moving parts.
Americans have been leery of tuned exhaust systems since the Japanese brought the first tuned-pipe motorcycles to Daytona Beach in the mid-1960s and wiped the Harleys and Triumphs off the map. Therefore, it's no surprise that when the rules for Formula I were being hashed out in the early 1970s, the prohibition of exhaust tuning was one of the first. An exhaust extractor, "for the sole purpose of carrying exhaust gases out of the cowling," was the closest anyone ever got to a tuned pipe in Formula I. Engine development on this side of the Atlantic focused on the effective use of nitro.
Scoring
Scoring in F3D is strange by American standards. Instead of competing against the other pilots in the heat to finish 10 laps and cross the finish line first, F3D contestants play "beat the clock." Each contestant's elapsed time, in seconds, is recorded, and 10% is added in case of a cut. The resulting score is translated into points for each round. As in golf, the lowest total score wins.
Advantages and disadvantages:
- Advantage: Your competitors cannot "tiptoe through the matrix" by lucking into easy heats and end up ahead of you on points, as can happen in AMA racing.
- Disadvantage: The pressure is always on; you can never relax and cruise around the poles—even when no one is chasing you. Each second goes on the scoreboard.
- Penalty: A no-start, flameout, or double cut results in a whopping 200 points added to your score.
The rules allow one throwaway score after the fifth round and one after the tenth, so that 200 can only become useful as a throwaway if you get another chance.
Life After T/V
F3D competition never really caught on in the US, perhaps because of the unique scoring method, or perhaps because the piped, alcohol-burning engines had a reputation for being finicky and hard to run.
However, the few US competitors who did venture into it managed to do very well. The team of Cliff Treadwell and Bob Violett proved nearly unbeatable in the 1970s with their T/V Bob C.A.T.
The Bob C.A.T. is one of those unique designs that took advantage of every conceivable loophole in the airframe specifications: in-line, two-wheel landing gear mounted amidships; a drooped stabilizer with tip skids; and a lack of draggy scale-like features such as a bubble canopy. It looked nothing like a full-scale airplane, but it was legal according to the rules.
Faced with the twin demons of dominance by US pilots yet an almost total lack of US participation, the modeling branch of the Fédération Aéronautique Internationale (FAI)—officially known as the CIAM, or International Aeromodeling Commission—was persuaded to adopt new airframe specs. The new guidelines mirrored those of Formula I—the leading event in the US—complete with a "replica" rule, under which each aircraft was required to resemble a full-scale prototype.
The rules change, which occurred in roughly 1985, was designed to increase US pilots' participation, and it did. Still, it did not result in a large-scale crossover from Formula I. Other than the biannual team trials, I know of no F3D races in the US.
F3D may have more interest now, after the demise of Formula I, and now that a new crop of razor-sharp pilots have gotten a taste of world-class speed in Quarter 40.
Post-1985 development proceeded in stages:
- The first F3D models fielded by US teams after the change were basically Formula I airframes with tuned pipes protruding from the stock Formula I cowl. An accompanying photo shows World Champion Dave Shadel, front and center, with one of those models—a Kazi.
- Later refinements enclosed the pipe within the fuselage, exemplified by the Rivets that World Champion Dub Jett (upper left in the photo) is holding. At the upper right, Dave Doyle holds a Denight of similar description.
- The third stage came with the Stiletto design by Gary Hoover. World Champion-type Richard Verano (lower left) holds a Stiletto. This model uses a fully enclosed, inverted engine installation, which remains the standard today.
An interesting offshoot was the de Havilland Tiger Moth monoplane (yes, there really was such a thing) fielded by Jim Katz and Greg Doe (lower right and top center respectively). These models presaged the development of today's ultralong wings.
Again, back to what the rules allow and what the laws of physics reward. No maximum wingspan is specified by the rules, and the "scale replica" requirement disappeared in 1993. Longer wings are more efficient than short wings; therefore, the proper wingspan for an F3D model nowadays is basically the longest you can get without folding the wing at the #1 pylon turn.
If someone comes up with a spar material stronger than carbon fiber, it will be in one of these models.
A Good Cross-section
Besides the tuned power plant and the glider wings, one other aspect of F3D may seem peculiar to US Pylon fans: the fuselage cross-sectional area requirement.
We Pylon racers are used to wing-area specs and fuselage height and width specs, but we generally don't concern ourselves with the "fatness" of the fuselage (unless we are developing a Quarter 40 kit, but most Q-40 contestants buy a kit from someone else, premeasured and preapproved by the design committee).
Two photos this month show how I—an inveterate scratch-builder, doomed by my stubbornness to continually try to invent a better mousetrap—went about developing an F3D fuselage and proved that it met the cross-section requirement.
The design is based on Art Williams' full-scale Formula I Estrellita, which I have always found appealing. The model I started with didn't meet the height or cross-section requirements for F3D, so I added a Mustang-style belly scoop.
To confirm that the scoop added enough area, I:
- tack-glued it in position on the fuselage,
- applied release agent (two coats of Johnson's wax and a coat of polyvinyl alcohol [PVA] over the wax),
- wrapped the whole assembly with several layers of heavy fiberglass cloth and wet epoxy resin,
- when cured, sawed it apart at the wing saddle and popped the halves loose,
- then sawed each half in half at the bulkhead line to produce a clean, flat "picture" of the fuselage at the point of maximum cross-section.
(Those of you with a CAT scanner in your basement could use that instead.)
I rejoined the top and bottom of one of the halves using duct tape, and I placed it over a piece of graph paper. The area is the same whether you use a 1/4-inch grid or a 1 mm grid; since the FAI rules use metric units, I went with the 1 mm grid.
Using a fine drafting pencil, I traced around the outside of the fiberglass piece and tallied the number of 1 mm squares enclosed by the resulting curve. It's simple!
Next month I'll have a description and photos of the new whizbang. You'll know if it crashes on the test flight, because I'll write about something else.
MA
Transcribed from original scans by AI. Minor OCR errors may remain.
