Radio Control Pylon Racing - 2008/02

148 MODEL AVIATION
WHEN I SAY I race
model airplanes as a
hobby, I get many
different reactions.
The majority of the
time people say “Oh,
that’s nice.” The more
interested ones ask
about the airplanes,
racecourse, scoring,
and so on. I enjoy
explaining these
things, and I will try
to explain some of them now for those of you who are not racers.
We generally compete in three classes in the US today: two classes
of Quickie 500 (Q-500), which has its roots in a model Glen Spickler
designed approximately 30 years ago, and Quarter 40 (Q-40), which
replaced Formula 1 in the 1990s. All are generally raced on the same
triangular course for 10 laps that are 1/4 mile each.
The slower of the Quickie classes is Sport Quickie (AMA event
424), which is the best place for a new racer to start. The rules require a
500-square-inch wing attached to a box cross-section fuselage. You can
build your own airplane from scratch if you like, but the Great Planes
Viper ARF and the Lanier Predator are so competitive you might as well
start with one of those.
The only common failure with these models is the firewall, which
isn’t built tough enough at the factory. Without modification the entire
firewall pops out with the first hard landing.
A generous fillet of epoxy and milled glass fiber applied to the
backside of the firewall where it meets the fuselage sides will remedy
this weak spot. You will need to remove the factory-applied glass cloth
in this area; it is simply ineffective, particularly on the Viper. I recently
MA’s new columnist starts with a review of Pylon basics
Also included in this column:
• Tips for getting started
• Thunder Tiger Pro .40 tips
• The new Profi 6.5cc RC engine
• Winter contests not to be
missed
[[email protected]]
Radio Control Pylon Racing Matt Russell
Left: Tom Strom Sr. with his caller, Tom Jr., after a record-setting
57.83 Q-40 flight. Congratulations, Tom!
Above: The innovative Profi 6.5cc RC, available from Jim Booker,
shares features with the top-performing MB .40 used in FAI.
used a sharp chisel to remove the factory glass cloth, but a Dremel tool
with a small pointed bit will do the job as well.
Make this modification before you fly the model. Repairs made to
the broken airplane never seem to hold up well, and it’s much easier to
do before you glue on the hatch that covers the fuel tank.
There is currently one approved engine for this event: the Thunder
Tiger Pro .40. It runs great, but there are a couple things to do to
increase its reliability in preparation for racing.
Back out the idle needle most of the way and glue it in place with
cyanoacrylate. This will improve the fuel flow and ensure that the
engine dies when the throttle is closed, to shut down for landing.
A weak link is the carburetor-barrel retaining screw. When it backs
out, the barrel comes loose and the spring behind it is ingested in the
engine, causing great damage. Most people toss the spring and glue the
retaining screw in place with cyanoacrylate. Some cyanoacrylate or
thread lock carefully applied to the needle-valve assembly where it
screws into the carburetor body is not a bad idea either.
Another consideration is that the factory rear bearing occasionally
fails, causing considerable internal damage. Boca Bearings sells a
bearing for less than $20 that will hold up better than the one that
comes installed at the factory. That is some cheap insurance.
The bolt that holds the front and rear halves of the muffler has been
impossible to obtain in the past, but it is now available as a replacement
part. At operating temperature the aluminum muffler expands more
than the steel bolt, which stretches somewhat, allowing the rear half of
the muffler to rotate and eventually leak.
Tightening the bolt and jam nut at the rear of the muffler solves this
problem only temporarily. The bolt will stretch some more, and
multiple cycles of stretching and retightening will eventually result in a
broken bolt and lost muffler parts.
I have seen various attempts at preventing these problems, one of
which is to apply a 2-inch length of bicycle inner tube with cable ties
over the joint between the front and rear half. That prevents the loss of
parts when the bolt finally gives up.
I have seen the muffler halves welded together, but the weld broke
02sig5.QXD 12/20/07 1:20 PM Page 148The author and his
daughter, Allie, at
the Q-40 Classic last
February. It is one of
the year’s premier
racing events.
February 2008 149
after several runs. Replacing the bolt with a
length of 4-40 threaded rod and multiple nuts
at both the front and rear has worked for some.
If you have another fix for this problem, let
me know and I will include it here for
everyone’s benefit.
Once you get the airplane together, go fly it
and trim it out. You will find that the models
track well and have no tendency to pitch up
with increased speed. With the CG set
properly, they will fly on knife edge for quite
sometime with no need for a rudder input.
Now it is time to find someone to race against.
If you do not know anyone who races in
your area, a good place to go is one of several
Pylon Racing forums. The National Miniature
Pylon Racing Association (NMPRA) is the
SIG that provides support to the AMA.
Forums on the NMPRA Web site will help
you find races and racers in your area. If you
are looking for other online information about
racing, check out the sites listed at the end of
the column. Dig around in the corners of those
sites, and you will find tons of helpful tips.
For those of you who race in the expert Q-500
class (AMA event 428), there is a new engine
available: the Profi 6.5cc RC. The same people
who manufacture the MB .40 that is used in
FAI-class F3D manufacture this engine, which
has some of the same features as the MB .40.
The inner race of the rear bearing is
eliminated since the crankshaft has a groove
machined in it that serves as the inner race.
The crankshaft/bearing assembly is inserted in
the case as a single unit. In addition, the
crankshaft is bored off-center to help with
balance and fuel feed. The piston is domed to
provide for better combustion.
At this time the engine has not been used
much in competition. It may take some
experience to learn how to optimize its
performance, but the potential is there.
Jim Booker is importing the 6.5cc, and he
claims that its superior-quality materials will
prove to be its strength. Tom Strom Sr.
operated one of the prototypes at Whidbey
Island in Washington this past summer and
entered it in the race unofficially to compare
with other airplanes. He felt that the engine
had great promise; it was the fastest at the
meet, flying roughly 1:05.
On the topic of Tom, he bested Travis
Flynn’s Q-40 record at the Shelton,
Washington, race in August, flying a blistering
57.83 in a heat against Jerrett Cangee, who
flew a Bruce DeChastel/Dan Kane Polecat. I
witnessed the race, and Tom’s flying was
extremely consistent. He backed that up with a
win at the North-South Shootout in Medford,
Oregon, two weeks later.
I have known Tom for more than 25
years, and he is always the one to beat in
our district. He has worked hard and
persistently to achieve this goal.
Congratulations, Tom!
My daughter and I just returned from the
final West Coast points race for the year,
which was held in Phoenix, Arizona. On the
first day of the race, eight of the 11 Q-40
contestants (I was included and set my
personal best time) flew approximately 1:04.
This was a tremendously competitive event!
If you have not had the opportunity to attend
a Phoenix race, try to schedule it in. The
SpeedWorld club can always find volunteers
who are willing to man the racecourse, and the
electronics that Jim Allen and Hank Kaufman
developed are world-class. Jim is a great CD,
and he gets everyone organized so things start
on time and the races proceed at an amazingly
fast pace.
The Winterfest Q-500 race will be held
January 19-20 for both slow and expert Quickie,
and the Q-40 Classic will be held February 23-
24. Last year 70 entrants from more than eight
countries competed in Q-40. Check the
NMPRA Web site for more information.
When my 14-year-old daughter tells her friends
she races model airplanes as a hobby, she gets a
slightly different reaction than I do. Most of her
classmates think she is a bit of a geek. If having
this much fun means being labeled “a bit of a
geek,” I guess we will just have to get used to it!
If you have information you would like for
me to publish here, contact me. Thanks for your
time. I’ll be back in two months. MA
Sources:
Big Bruce Racing Products
www.bigbruceracing.com
California Speed Pros
(605) 787-6340
www.calspeedpros.com
Darrol Cady
(360) 903-3520
www.darrolcady.com
Dr. Martin Hepperle
0 531 352 936
www.mh-aerotools.de
Fly Fast Composites
(306) 585-1465
www.flyfastcomposites.com
H&M Racing Inc.
(306) 892-4216
www.hmracinginc.com
Jett Engineering, Inc.
(713) 680-8113
www.jettengineering.com
Jim Booker
www.flycontrolline.com
Matney Models
(734) 848-8195
www.matneymodels.com
NMPRA
www.nmpra.org
Performance Specialties
(775) 265-7523
www.pspec.com
PylonWorld
(704) 968-2881
www.pylonworld.com
RCGroups
885 NW Grant Ave. #B
Corvallis OR 97330
www.rcgroups.com
SuperT Radio Control Products
(847) 878-4161
www.supertrc.com
TEAMseaholm
(816) 686-4808
www.teamseaholm.com
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