146 MODEL AVIATION
TIMING OF A Speed flight is the act that tells us how our model
performed. Today, many good digital stopwatches are available
that range from those built into a wristwatch to ones with special
functions. A few allow split timing so that a single lap can be
timed while the whole flight is being timed. When the flight is
completed, the time still needs to be converted to mph to
determine how well it went.
A company named Technika has made this a much easier task.
It sells a watch that is marketed to the NASCAR crowd called the
Speed Calculating Stopwatch. It has a function where the distance
of the timed event is entered. In the Formula 40 event, you would
enter the distance of one mile. At the model’s release, the watch
is started, and when stopped at the end of 14 laps, the speed is
displayed in mph. For other events that require timing on a 1⁄2-
mile distance, .5 is entered.
The watch can be set up for English or metric lengths. It will
allow as many as 100 split times. This feature would allow you to
record each lap of a timed run.
You can order the watch through Technika’s Web site at
www.technika.com or by calling the sales office at (480) 348-
0278. Ask for item 810047. It sells for $38 plus shipping.
After mine arrived, I began playing with it and noticed that it
did not agree with the old speed charts that I had been using, so I
called Technika to ask why. I was informed that the algorithms in
the watch are correct. The company representative offered to
supply documents certifying its accuracy back to the US Bureau
of Standards.
Why is there a difference? It is slight—approximately a few
hundredths of a mile per hour. The difference occurs because the
distance we fly is not an exact 1⁄2-mile or mile length. The
calculations on many of the timing charts were based on the
assumption that the distance was exact.
To sidestep these small differences, the North American Speed
Society (NASS) strongly suggests that all contest speeds be
arrived at by using a set of formulas that are printed several times
each year in the NASS newsletter, Speed Times.
The small error in the speed calculated by the watch does not
detract from its value to a Speed flier, but contest speeds will
need to be calculated to determine placing.
CONTROL LINE SPEED
Dave Mark, Box 371, Fenton MI 48430; E-mail: [email protected]
Technika’s Speed Calculating Stopwatch displays a speed of
157.89 mph for a lap time of 11.40 seconds.
The bottom view of the author’s model shows how the pan was
cut to a short length to save weight.
To improve strength, remove the ring on the spinner’s backplate
so more wood is left between the spinner and intake.
In a previous column, I described my plans to construct a lighter
model for the Formula 40 event. I had been flying a Nelson .40-
powered model that weighed 27.6 ounces without fuel. The old
airplane had turned a speed of 159.0 on its best day—a flight early in
the day as a high-pressure area moved over the contest site in Dayton,
Ohio. Subsequent flights that day ranged from 153.0 mph to 157.5.
12sig5.QXD 10/22/04 1:35 pm Page 146
My new model weighs 21.9 ounces
without fuel. It is constructed from
basswood and balsa wood. The only hightech
items used in its construction were
four strips of .015 x .25 x 12-inch carbon
fiber that I inserted into the LE and TE of
the wing to increase resistance to
handling dents.
During the 2004 contest season, the
model finished second at the Nats and
took three first places with a best speed of
161.1. The decrease in weight has been
good for roughly 3 mph. This is a great
return for the effort at weight reduction.
Holding the length of the magnesium
pan to 5.25 inches produced a large
weight savings. The pan is held in place
with four bolts. Two are located just
behind the spinner and two are at the very
rear of the pan. The area behind the pan
was replaced with a carved balsa block.
I tried to use 1⁄64 plywood that I
wrapped around a form. This was lighter,
but it did not have the strength to resist
my grip. I hold onto this section of the
model when starting the engine.
The crutch for the body was cut from
1⁄2 basswood. The sidewall area of the
crutch behind the wing was cut to 3⁄32 inch
in thickness. The area from the wing to
the rear of the model was covered with
1⁄64 plywood.
One problem area to watch out for in
the crutch is the small section between the
spinner and the front intake. This area
will get so thin that it is easily broken
during building. To strengthen this
section, epoxy a piece of 1⁄4 basswood
with the grain running across the crutch
or 90° to the crutch grain. This will
strengthen the nose tremendously.
The backplate of the Nelson spinner
should be modified as shown in the
December 2004 147
picture so that the clearance required for it
is reduced. The center-section of the wing
is cut in a diamond shape from 1⁄4
basswood. The center of the diamond
measures 1⁄8-inch wider than the 13⁄4-inch
Morris bellcrank. The basswood diamond
tapers to 1⁄4-inch wide at the wingtips. On
the inboard side of the diamond, 3⁄32-inch
grooves are cut in the front and back for
the control wires.
The LEs and TEs are made from
lightweight 1⁄4 balsa. These will dent easily
and possibly blow off at high speed. By
inserting the strips of carbon fiber
described earlier in the LE and TE on each
side of the wing, that can be stopped. It
will stiffen the balsa without a large weight
gain.
The stabilizer is 1⁄8 basswood. It is
important to cut a large radius on the tip of
the stabilizer and wing. If the tips remain
square, they will flutter and wipe off great
amounts of speed before they fail.
The model was finished with two coats
of epoxy resin. The first coat was applied,
and after five minutes, all of the resin that
had not soaked in was wiped off with paper
towel. I sanded the model, dusted it off,
and applied another coat of resin. I wiped
off the excess after five minutes, sanded it
again, then applied two coats of clear dope
thinned 50%.
Initially I used a 11⁄8-inch wheel on my
model in an effort to keep the weight
down. This resulted in an airplane that
rolled toward a stop and then gently
flipped over. A larger wheel changed this
inelegant finish into a good flight.
Many modelers think that to begin
flying Speed, they need the most high-tech
model. This information shows that it is
not the case. You don’t need a molded
carbon-fiber model to be competitive. A
clean model, constructed from standard
basswood and balsa, will get the beginner
started.
Anyone who has an interest in flying
Speed should consider joining NASS. The
group’s newsletter is published four times
a year. It is filled with information about
model design and engine work, contains
contest reports and a parts finder, and
features many other items relating to
Speed. The Web site is www.clspeed.com,
or write to Box 371, Fenton MI 48430. MA
www.modelaircraft.org
12sig5.QXD 10/22/04 1:35 pm Page 147
Edition: Model Aviation - 2004/12
Page Numbers: 146,147
Edition: Model Aviation - 2004/12
Page Numbers: 146,147
146 MODEL AVIATION
TIMING OF A Speed flight is the act that tells us how our model
performed. Today, many good digital stopwatches are available
that range from those built into a wristwatch to ones with special
functions. A few allow split timing so that a single lap can be
timed while the whole flight is being timed. When the flight is
completed, the time still needs to be converted to mph to
determine how well it went.
A company named Technika has made this a much easier task.
It sells a watch that is marketed to the NASCAR crowd called the
Speed Calculating Stopwatch. It has a function where the distance
of the timed event is entered. In the Formula 40 event, you would
enter the distance of one mile. At the model’s release, the watch
is started, and when stopped at the end of 14 laps, the speed is
displayed in mph. For other events that require timing on a 1⁄2-
mile distance, .5 is entered.
The watch can be set up for English or metric lengths. It will
allow as many as 100 split times. This feature would allow you to
record each lap of a timed run.
You can order the watch through Technika’s Web site at
www.technika.com or by calling the sales office at (480) 348-
0278. Ask for item 810047. It sells for $38 plus shipping.
After mine arrived, I began playing with it and noticed that it
did not agree with the old speed charts that I had been using, so I
called Technika to ask why. I was informed that the algorithms in
the watch are correct. The company representative offered to
supply documents certifying its accuracy back to the US Bureau
of Standards.
Why is there a difference? It is slight—approximately a few
hundredths of a mile per hour. The difference occurs because the
distance we fly is not an exact 1⁄2-mile or mile length. The
calculations on many of the timing charts were based on the
assumption that the distance was exact.
To sidestep these small differences, the North American Speed
Society (NASS) strongly suggests that all contest speeds be
arrived at by using a set of formulas that are printed several times
each year in the NASS newsletter, Speed Times.
The small error in the speed calculated by the watch does not
detract from its value to a Speed flier, but contest speeds will
need to be calculated to determine placing.
CONTROL LINE SPEED
Dave Mark, Box 371, Fenton MI 48430; E-mail: [email protected]
Technika’s Speed Calculating Stopwatch displays a speed of
157.89 mph for a lap time of 11.40 seconds.
The bottom view of the author’s model shows how the pan was
cut to a short length to save weight.
To improve strength, remove the ring on the spinner’s backplate
so more wood is left between the spinner and intake.
In a previous column, I described my plans to construct a lighter
model for the Formula 40 event. I had been flying a Nelson .40-
powered model that weighed 27.6 ounces without fuel. The old
airplane had turned a speed of 159.0 on its best day—a flight early in
the day as a high-pressure area moved over the contest site in Dayton,
Ohio. Subsequent flights that day ranged from 153.0 mph to 157.5.
12sig5.QXD 10/22/04 1:35 pm Page 146
My new model weighs 21.9 ounces
without fuel. It is constructed from
basswood and balsa wood. The only hightech
items used in its construction were
four strips of .015 x .25 x 12-inch carbon
fiber that I inserted into the LE and TE of
the wing to increase resistance to
handling dents.
During the 2004 contest season, the
model finished second at the Nats and
took three first places with a best speed of
161.1. The decrease in weight has been
good for roughly 3 mph. This is a great
return for the effort at weight reduction.
Holding the length of the magnesium
pan to 5.25 inches produced a large
weight savings. The pan is held in place
with four bolts. Two are located just
behind the spinner and two are at the very
rear of the pan. The area behind the pan
was replaced with a carved balsa block.
I tried to use 1⁄64 plywood that I
wrapped around a form. This was lighter,
but it did not have the strength to resist
my grip. I hold onto this section of the
model when starting the engine.
The crutch for the body was cut from
1⁄2 basswood. The sidewall area of the
crutch behind the wing was cut to 3⁄32 inch
in thickness. The area from the wing to
the rear of the model was covered with
1⁄64 plywood.
One problem area to watch out for in
the crutch is the small section between the
spinner and the front intake. This area
will get so thin that it is easily broken
during building. To strengthen this
section, epoxy a piece of 1⁄4 basswood
with the grain running across the crutch
or 90° to the crutch grain. This will
strengthen the nose tremendously.
The backplate of the Nelson spinner
should be modified as shown in the
December 2004 147
picture so that the clearance required for it
is reduced. The center-section of the wing
is cut in a diamond shape from 1⁄4
basswood. The center of the diamond
measures 1⁄8-inch wider than the 13⁄4-inch
Morris bellcrank. The basswood diamond
tapers to 1⁄4-inch wide at the wingtips. On
the inboard side of the diamond, 3⁄32-inch
grooves are cut in the front and back for
the control wires.
The LEs and TEs are made from
lightweight 1⁄4 balsa. These will dent easily
and possibly blow off at high speed. By
inserting the strips of carbon fiber
described earlier in the LE and TE on each
side of the wing, that can be stopped. It
will stiffen the balsa without a large weight
gain.
The stabilizer is 1⁄8 basswood. It is
important to cut a large radius on the tip of
the stabilizer and wing. If the tips remain
square, they will flutter and wipe off great
amounts of speed before they fail.
The model was finished with two coats
of epoxy resin. The first coat was applied,
and after five minutes, all of the resin that
had not soaked in was wiped off with paper
towel. I sanded the model, dusted it off,
and applied another coat of resin. I wiped
off the excess after five minutes, sanded it
again, then applied two coats of clear dope
thinned 50%.
Initially I used a 11⁄8-inch wheel on my
model in an effort to keep the weight
down. This resulted in an airplane that
rolled toward a stop and then gently
flipped over. A larger wheel changed this
inelegant finish into a good flight.
Many modelers think that to begin
flying Speed, they need the most high-tech
model. This information shows that it is
not the case. You don’t need a molded
carbon-fiber model to be competitive. A
clean model, constructed from standard
basswood and balsa, will get the beginner
started.
Anyone who has an interest in flying
Speed should consider joining NASS. The
group’s newsletter is published four times
a year. It is filled with information about
model design and engine work, contains
contest reports and a parts finder, and
features many other items relating to
Speed. The Web site is www.clspeed.com,
or write to Box 371, Fenton MI 48430. MA
www.modelaircraft.org
12sig5.QXD 10/22/04 1:35 pm Page 147
