118 MODEL AVIATION
SEE YA “LASER”! The April 2004 column featured behind-thescenes
commentary from Dave Norman, who designed the Seeker
Quickie 500 (Q-500) racer. He described how he went from the basic
rules requirements (see www.modelaircraft.org/templates/ama/
compreg.asp under “RC Pylon Racing”) to selecting key features based
on observing other designs, drawing plans using a simple CAD
program, and sending the CAD files to a laser-cutting shop to have the
parts cut for easy assembly.
Laser-cutting is rapidly entering the mainstream. As prices drop and
more modelers become proficient with CAD, it’s now possible to
produce your own custom kit without going through the laborious task
of transferring your drawings to the wood, cutting the parts, and
sanding them to fit.
Of course you still have to glue them together; that’s almost a lost
art these days. But again, high technology comes to the rescue.
A picture is worth a thousand words, and a CD can hold a thousand
pictures. CDs now sell for approximately a buck each. As part of his
preparation for selling kits, Dave has begun work on an assembly
manual with many high-quality digital photos, which he plans to
release on CD. It’s shaping up to be a great how-to for any model of
this kind. An advance copy is available for viewing and download on
Lewis Schwab’s Web site at www.lcsperformance.com/seeker/
SeekerInstructions.html and at the North Central Pylon League’s Web
site at www.ncplracing.org/.
The Seeker is not commercially available yet, and this mention is
not intended to be an endorsement. I simply believe that this story
offers a fascinating glimpse at what goes into a homegrown
competitive effort—and, to the extent Dave is willing to share his
insight and knowledge gained along the way, it can only help
demystify and popularize this wonderful sport.
“Wood” I? The wood-versus-composite battle has been raging for
roughly 10 years. In one corner we have Wood, wearing trunks that read
“Cheaper but Not as Fast.” In the opposite corner we have Composite,
wearing trunks that read “Experts Only! You Can’t Afford It!”
There are very few pure wood airplanes out there; most use spaceage
materials such as carbon fiber for reinforcement. And those who
produce composite airplanes are rediscovering the value of wood,
incorporating it into their all-molded structures because it’s better in
many ways—not just cheaper.
One such manufacturer is Bruce DeChastel. His new Shotgun Q-
500 and Polecat Quarter 40 (Q-40) are assembled with a great deal of
time and care, using materials that include balsa. Because time is
money, they aren’t cheap. They are composite and they are wood. Go
to www.bigbruceracing.com/ to see these models.
(The Shotgun has a conventional tail—not a V-tail. At one of our
local races in May, John Williams set a course record of 1:12 with the
Shotgun his first time out with it. Who says you need a V-tail to go
fast?)
The moral of this story is that you can always make your way into
the winners’ circle by investing time rather than money, if that is your
choice. The availability of CAD and laser cutting only makes it that
much easier.
Duane Gall, 1267 S. Beeler Ct., Denver CO 80231; E-mail: [email protected]
RADIO CONTROL PYLON RACING
The “Young Guns”—the top three at the 2003 NMPRA Q-40
Champs (L-R): Tim Lime, Gary Freeman Jr., and Travis Flynn.
The business end of the author’s Q-40 aircraft with a fully legal
bored-out Q-500 carburetor. Text has details.
Matias Salar’s Q-40 Miss Ashley II at 2003 Champs at SpeedWorld
R/C Flyers’ field (Phoenix AZ). Sean Dunnavant photos.
09sig4.QXD 6/23/04 1:07 pm Page 118
Based on Dave Norman’s experiences as
published here, I’ve begun work on a woodfuselage
Q-40. The complex curves will
present a challenge, but the gains in stiffness
and lightness should make the effort
worthwhile. I’ll keep you posted.
STOL Survivor: Q-40 was conceived as a
more scalelike sister event for Q-500 using an
engine that is the same physical size (.40 cu.
in.) and shares many of the same parts. Yet
there hasn’t been much “cross-pollination.”
Even in areas where Quickie is popular, local
Q-40 races are rare. Why is this?
I don’t think there’s one simple answer, but
rather a combination of factors working
together. One may be the awesome airspeed:
180+ mph. Not that airspeed by itself is bad;
many sport fliers like to stuff extra horsepower
up front—sometimes more than the airframe
can handle. And model-jet pilots pride
themselves on achieving 200 mph or more in
short bursts. But precision flying, lap after lap,
close to the ground at a steady 180 mph? Well,
that takes some getting used to.
Another factor may be the cost of the
airplanes. To handle the flight loads at these
speeds, Q-40 models must be well engineered
and carefully built. This means that you must
either purchase a composite airframe for $350
or more or invest an equivalent amount of time
in building an airworthy model.
A reasonably priced substitute is the
Kangke F3D/30. Some pilots are using it to get
their feet wet, so to speak, because it looks and
flies much like a Q-40. But because it’s not a
model “of” any specific full-scale racer and
doesn’t quite meet the dimensional specs, it
isn’t legal for competition. You can see the
F3D/30 at www.pylonworld.com/rc_pylon/q-
3/planes/q-3_planes_f3d_30.htm.
A factor, until recently, was the need for a
custom-made wooden propeller. The high-rpm
Q-40 engines aren’t happy with an off-theshelf
wooden propeller, and a custom-whittled
one will set you back $35 or more. A couple of
bad landings could cost you a month’s grocery
money.
That issue has gone away because the
Contest Board has approved the APC 7.4 x 8.0
carbon-fiber propeller (part LP07480C): a $10
item that is more durable than wood and as fast
as anything in competition.
Of course, the number of flying fields that
require Short Takeoff & Landing, or STOL,
techniques, for which a Quickie or other lightly
loaded, slow-landing airplane is better suited,
has to be considered. We don’t all have a
square mile of concrete on which to play.
A last factor, which I believe may work in
combination with the other four, is the fact that
Q-40s typically have no throttle. The accepted
method is simply to rig a servo so it pinches
the fuel line, starving the engine.
If the airplane is the least bit out of trim on
a test flight, one gets the uncomfortable
feeling of having a “tiger by the tail.” The
choice is between fumbling for the trim
levers while trying to steer the model at top
speed or shutting the engine off and
immediately setting up a dead-stick landing
approach with a new, expensive, out-of-trim
September 2004 119
airplane. And if you miss the runway by a
few inches, your engine will swallow a
bushel of dirt through that huge, open
venturi. (See accompanying action photo.)
For us hairy-chested racers, that’s the
definition of a relaxing afternoon. But can
you blame a new person—or even an
experienced Quickie pilot—for believing
otherwise? Well, I got to thinking and decided
that there just had to be a better way.
Using a Quickie-style carburetor seemed a
natural choice. Nelson and Jett make them.
They will interchange easily with the Q-40
venturi because the Quickie and Q-40
crankcases are the same.
However, the stock carburetor will
definitely slow you down; the engine will turn
200-500 rpm less compared with the venturi.
Both have the same inner diameter, but the
venturi’s trumpet shape gives better airflow.
So obviously the answer was to open up
the Q-500 carburetor so that its inner shape
matched the venturi’s. As long as the barrel
stayed open and the contours were smooth
inside, the air wouldn’t know the difference
and it should run just as fast.
That raised the question I’ve heard so
often since then: “Hey, can you do that?”
Yep! Get out your rule book. The rule for Q-
40, AMA event 422, specifies in section
16.1.2. (Powerplant), paragraph 3 (Intake:), “a
single carburetor or venturi with a maximum
inner diameter of 9 mm (0.3543 inch).
Carburetors or venturis may be modified and
are not subject to availability rules.” (I added
the italics.)
It was easy from there. Holding the
throttle arm in the full open (high throttle)
position, I drilled a 1⁄16-inch-diameter hole
through the arm and partway into the
carburetor body. Then I inserted a 1⁄16-inchdiameter
temporary pin to hold the barrel
open. Working slowly and carefully on a
drill-press stand (wearing safety glasses, of
course), I flared the opening with a Vermont
American 3⁄8-inch Beading Router Bit until
the edge of the intake was so thin I had to
stop.
At that point I switched to a 1⁄2-inch
tapered reamer, working by hand until the
tapering cut was visible approximately
halfway down the rotating part of the
carburetor barrel. And just for good measure I
did the same thing on the bottom end to give
the air channel sort of an hourglass shape. I
blended the curves with a Dremel Moto-Tool
felt cone and polishing compound.
The last step was to gently run a 9mm drill
bit through the barrel to make sure it was
exactly as large as the rules allow.
An accompanying photo shows the result.
The engine is a Jett. The procedure is the
same for a Nelson except that its plastic
carburetor material cuts more easily than
aluminum. Therefore, the first step can be
accomplished using a handheld electric drill.
But does it work? If it didn’t, I wouldn’t
be recommending it here. I ran several
tachometer tests and cannot measure a
difference between the modified carburetor
and the venturi. In addition, I posted my best
time ever (a 1:06) at the JR/PowerMaster
Gold Cup race earlier this year using the
engine shown.
This setup will not actually idle. Landings
are still dead-stick. But it does allow you to
reduce power and cruise for a while until you
decide it’s time to set up an approach. You can
also throttle back on the starting line to keep
the engine cool—your engine may last longer
because the shutdown is rich rather than
lean—and if you’re making the transition to
Q-40 from something slower, you can fly the
course at a reduced setting to start, and then
open ’er up when you feel comfortable.
That’s all for now. Stay safe and don’t forget
to read your rules! MA
09sig4.QXD 6/23/04 1:08 pm Page 119
Edition: Model Aviation - 2004/09
Page Numbers: 118,119
Edition: Model Aviation - 2004/09
Page Numbers: 118,119
118 MODEL AVIATION
SEE YA “LASER”! The April 2004 column featured behind-thescenes
commentary from Dave Norman, who designed the Seeker
Quickie 500 (Q-500) racer. He described how he went from the basic
rules requirements (see www.modelaircraft.org/templates/ama/
compreg.asp under “RC Pylon Racing”) to selecting key features based
on observing other designs, drawing plans using a simple CAD
program, and sending the CAD files to a laser-cutting shop to have the
parts cut for easy assembly.
Laser-cutting is rapidly entering the mainstream. As prices drop and
more modelers become proficient with CAD, it’s now possible to
produce your own custom kit without going through the laborious task
of transferring your drawings to the wood, cutting the parts, and
sanding them to fit.
Of course you still have to glue them together; that’s almost a lost
art these days. But again, high technology comes to the rescue.
A picture is worth a thousand words, and a CD can hold a thousand
pictures. CDs now sell for approximately a buck each. As part of his
preparation for selling kits, Dave has begun work on an assembly
manual with many high-quality digital photos, which he plans to
release on CD. It’s shaping up to be a great how-to for any model of
this kind. An advance copy is available for viewing and download on
Lewis Schwab’s Web site at www.lcsperformance.com/seeker/
SeekerInstructions.html and at the North Central Pylon League’s Web
site at www.ncplracing.org/.
The Seeker is not commercially available yet, and this mention is
not intended to be an endorsement. I simply believe that this story
offers a fascinating glimpse at what goes into a homegrown
competitive effort—and, to the extent Dave is willing to share his
insight and knowledge gained along the way, it can only help
demystify and popularize this wonderful sport.
“Wood” I? The wood-versus-composite battle has been raging for
roughly 10 years. In one corner we have Wood, wearing trunks that read
“Cheaper but Not as Fast.” In the opposite corner we have Composite,
wearing trunks that read “Experts Only! You Can’t Afford It!”
There are very few pure wood airplanes out there; most use spaceage
materials such as carbon fiber for reinforcement. And those who
produce composite airplanes are rediscovering the value of wood,
incorporating it into their all-molded structures because it’s better in
many ways—not just cheaper.
One such manufacturer is Bruce DeChastel. His new Shotgun Q-
500 and Polecat Quarter 40 (Q-40) are assembled with a great deal of
time and care, using materials that include balsa. Because time is
money, they aren’t cheap. They are composite and they are wood. Go
to www.bigbruceracing.com/ to see these models.
(The Shotgun has a conventional tail—not a V-tail. At one of our
local races in May, John Williams set a course record of 1:12 with the
Shotgun his first time out with it. Who says you need a V-tail to go
fast?)
The moral of this story is that you can always make your way into
the winners’ circle by investing time rather than money, if that is your
choice. The availability of CAD and laser cutting only makes it that
much easier.
Duane Gall, 1267 S. Beeler Ct., Denver CO 80231; E-mail: [email protected]
RADIO CONTROL PYLON RACING
The “Young Guns”—the top three at the 2003 NMPRA Q-40
Champs (L-R): Tim Lime, Gary Freeman Jr., and Travis Flynn.
The business end of the author’s Q-40 aircraft with a fully legal
bored-out Q-500 carburetor. Text has details.
Matias Salar’s Q-40 Miss Ashley II at 2003 Champs at SpeedWorld
R/C Flyers’ field (Phoenix AZ). Sean Dunnavant photos.
09sig4.QXD 6/23/04 1:07 pm Page 118
Based on Dave Norman’s experiences as
published here, I’ve begun work on a woodfuselage
Q-40. The complex curves will
present a challenge, but the gains in stiffness
and lightness should make the effort
worthwhile. I’ll keep you posted.
STOL Survivor: Q-40 was conceived as a
more scalelike sister event for Q-500 using an
engine that is the same physical size (.40 cu.
in.) and shares many of the same parts. Yet
there hasn’t been much “cross-pollination.”
Even in areas where Quickie is popular, local
Q-40 races are rare. Why is this?
I don’t think there’s one simple answer, but
rather a combination of factors working
together. One may be the awesome airspeed:
180+ mph. Not that airspeed by itself is bad;
many sport fliers like to stuff extra horsepower
up front—sometimes more than the airframe
can handle. And model-jet pilots pride
themselves on achieving 200 mph or more in
short bursts. But precision flying, lap after lap,
close to the ground at a steady 180 mph? Well,
that takes some getting used to.
Another factor may be the cost of the
airplanes. To handle the flight loads at these
speeds, Q-40 models must be well engineered
and carefully built. This means that you must
either purchase a composite airframe for $350
or more or invest an equivalent amount of time
in building an airworthy model.
A reasonably priced substitute is the
Kangke F3D/30. Some pilots are using it to get
their feet wet, so to speak, because it looks and
flies much like a Q-40. But because it’s not a
model “of” any specific full-scale racer and
doesn’t quite meet the dimensional specs, it
isn’t legal for competition. You can see the
F3D/30 at www.pylonworld.com/rc_pylon/q-
3/planes/q-3_planes_f3d_30.htm.
A factor, until recently, was the need for a
custom-made wooden propeller. The high-rpm
Q-40 engines aren’t happy with an off-theshelf
wooden propeller, and a custom-whittled
one will set you back $35 or more. A couple of
bad landings could cost you a month’s grocery
money.
That issue has gone away because the
Contest Board has approved the APC 7.4 x 8.0
carbon-fiber propeller (part LP07480C): a $10
item that is more durable than wood and as fast
as anything in competition.
Of course, the number of flying fields that
require Short Takeoff & Landing, or STOL,
techniques, for which a Quickie or other lightly
loaded, slow-landing airplane is better suited,
has to be considered. We don’t all have a
square mile of concrete on which to play.
A last factor, which I believe may work in
combination with the other four, is the fact that
Q-40s typically have no throttle. The accepted
method is simply to rig a servo so it pinches
the fuel line, starving the engine.
If the airplane is the least bit out of trim on
a test flight, one gets the uncomfortable
feeling of having a “tiger by the tail.” The
choice is between fumbling for the trim
levers while trying to steer the model at top
speed or shutting the engine off and
immediately setting up a dead-stick landing
approach with a new, expensive, out-of-trim
September 2004 119
airplane. And if you miss the runway by a
few inches, your engine will swallow a
bushel of dirt through that huge, open
venturi. (See accompanying action photo.)
For us hairy-chested racers, that’s the
definition of a relaxing afternoon. But can
you blame a new person—or even an
experienced Quickie pilot—for believing
otherwise? Well, I got to thinking and decided
that there just had to be a better way.
Using a Quickie-style carburetor seemed a
natural choice. Nelson and Jett make them.
They will interchange easily with the Q-40
venturi because the Quickie and Q-40
crankcases are the same.
However, the stock carburetor will
definitely slow you down; the engine will turn
200-500 rpm less compared with the venturi.
Both have the same inner diameter, but the
venturi’s trumpet shape gives better airflow.
So obviously the answer was to open up
the Q-500 carburetor so that its inner shape
matched the venturi’s. As long as the barrel
stayed open and the contours were smooth
inside, the air wouldn’t know the difference
and it should run just as fast.
That raised the question I’ve heard so
often since then: “Hey, can you do that?”
Yep! Get out your rule book. The rule for Q-
40, AMA event 422, specifies in section
16.1.2. (Powerplant), paragraph 3 (Intake:), “a
single carburetor or venturi with a maximum
inner diameter of 9 mm (0.3543 inch).
Carburetors or venturis may be modified and
are not subject to availability rules.” (I added
the italics.)
It was easy from there. Holding the
throttle arm in the full open (high throttle)
position, I drilled a 1⁄16-inch-diameter hole
through the arm and partway into the
carburetor body. Then I inserted a 1⁄16-inchdiameter
temporary pin to hold the barrel
open. Working slowly and carefully on a
drill-press stand (wearing safety glasses, of
course), I flared the opening with a Vermont
American 3⁄8-inch Beading Router Bit until
the edge of the intake was so thin I had to
stop.
At that point I switched to a 1⁄2-inch
tapered reamer, working by hand until the
tapering cut was visible approximately
halfway down the rotating part of the
carburetor barrel. And just for good measure I
did the same thing on the bottom end to give
the air channel sort of an hourglass shape. I
blended the curves with a Dremel Moto-Tool
felt cone and polishing compound.
The last step was to gently run a 9mm drill
bit through the barrel to make sure it was
exactly as large as the rules allow.
An accompanying photo shows the result.
The engine is a Jett. The procedure is the
same for a Nelson except that its plastic
carburetor material cuts more easily than
aluminum. Therefore, the first step can be
accomplished using a handheld electric drill.
But does it work? If it didn’t, I wouldn’t
be recommending it here. I ran several
tachometer tests and cannot measure a
difference between the modified carburetor
and the venturi. In addition, I posted my best
time ever (a 1:06) at the JR/PowerMaster
Gold Cup race earlier this year using the
engine shown.
This setup will not actually idle. Landings
are still dead-stick. But it does allow you to
reduce power and cruise for a while until you
decide it’s time to set up an approach. You can
also throttle back on the starting line to keep
the engine cool—your engine may last longer
because the shutdown is rich rather than
lean—and if you’re making the transition to
Q-40 from something slower, you can fly the
course at a reduced setting to start, and then
open ’er up when you feel comfortable.
That’s all for now. Stay safe and don’t forget
to read your rules! MA
09sig4.QXD 6/23/04 1:08 pm Page 119