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; and 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 $4 per gallon 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 development of F3D aircraft during the 1980s is illustrated with various pilots and models. Text has details.
Duane Gall, 1267 S. Beeler Ct., Denver CO 80231; E-mail: [email protected]
RADIO CONTROL PYLON RACING
Measuring the fuselage cross-sectional area, step 2.
The author demonstrates his method for measuring a new F3D
model’s fuselage cross-sectional area. This is step 1.
108 M ODEL AVIATION
110 M ODEL AVIATION
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
would focus on the effective use of nitro.
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.
This scoring method has advantages
and disadvantages for the contestant.
One advantage is that your competitors
cannot “tiptoe through the matrix” by
lucking into easy heats, and end up
ahead of you on points, as they can in
AMA racing.
The disadvantage is that the pressure
is always on; you can never relax and
cruise around the poles—even when no
one is chasing you. Each second will go
on the scoreboard.
And a no-start, flameout, or doublecut
results in a whopping 200 points
added to your score. At that point, your
only hope is to use that 200 as a
“throwaway” at the next opportunity.
(The rules allow one throwaway after the
fifth round and one after the 10th.)
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, alcoholburning
engines had a reputation of 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 Telford and Bob
Violett proved nearly unbeatable in the
1970s with their T/V Bob C.A.T.
I wish I had a picture of the Bob
C.A.T. to share with you. This unique
design took advantage of each
conceivable loophole in the airframe
specifications, with its in-line, twowheel
landing gear mounted amidships,
drooped stabilizer with tip skids, and
lack of draggy scalelike features, such
as a bubble canopy.
The Bob C.A.T. looked nothing like a
full-scale airplane, but it was legal
according to the rules.
Perhaps the event founders hoped the
model racing airplanes would resemble their
full-scale counterparts, but didn’t see it
necessary to bog down the rules with
verbiage specifying what sort of innovations
are allowable and what sort aren’t.
The laws of physics prevailed under
those nice, simple rules, and the result
was the Bob C.A.T.
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, and did,
increase US pilots’ participation, but it
still did not result in any 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.
The first F3D models fielded by US
teams after the change were basically
Formula Is with tuned pipes protruding
from the stock Formula I cowls. An
accompanying photo shows World
Champion Dave Shadel, front and
center, with one of these models—a
Kazi.
Later refinements resulted in enclosing
the pipe within the fuselage, exemplified
by the Rivets that World Champion Dub
Jett, at the upper left, is holding. At the
upper right, Dave Doyle holds a Denight
of similar description.
The third stage in post-1985 airframe
development came with the Stiletto
design by Gary Hover. World
Champion-type Richard Verano holds a
Stiletto at the lower left. This model
used 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, at the lower
right and the 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 wingarea
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 the release
agent (two coats of Johnson’s™ wax
and a coat of polyvinyl alcohol [PVA]
over the wax), and wrapped the whole
assembly with several layers of heavy
fiberglass cloth and wet epoxy resin.
When the assembly cured, I sawed it
apart at the wing saddle, popped the
halves loose, then sawed each half in
half at the black line shown in the
photo, to produce a clean, flat “picture”
of the fuselage at the point of maximum
cross-section.
(Of course, 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 1mm grid; since the
FAI rules use metric units, I went with
the 1mm grid.
Using a fine drafting pencil, I traced
around the inside of the fiberglass piece
and tallied the number of 1mm 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
