Old-Timers - 2009/02

THE
BOEHLE
GIANT is Vernon
Boehle’s (pronounced
“Bailey’s”) best-known
design, even though he had a
much better competition
record with several original
rubber-powered designs.
That success with Rubber
models is credited with ending
the era of seeing twin pushers in
the winner’s circle.
In turn, although Vernon’s Rubber
airplanes performed admirably in the 1933
Nationals, they were eclipsed by a new form of
power. Maxwell Bassett won all three Outdoor events with the first
really successful gasoline-engine-powered model.
In the early days, there was no provision for flying—or not flying,
for that matter—airplanes powered by gas engines against those
powered with the conventional rubber. However, that changed after
Maxwell Bassett’s performance; the Rubber and Gas categories were
soon separated. But the history of Maxwell Bassett and the Brown
Junior engine is another story for another time.
Vernon took the Giant, which has become known as the Boehle
Giant, to the 1936 Nationals, to compete in the Texaco category. Its
impressive 15-foot wingspan was an attempt to take maximum
advantage of the fuel-allotment event, and it caused quite a stir. But
the engine power at the time was not enough to support that much
airplane, and its performance didn’t live up to the promise.
Also included in this column:
• Seven Wedgys
• FF ignition worries?
• The four-stroke back flip
After his successful modeling career
during the 1930s, Vernon Boehle, as did
many modelers of the time, became a World
War II fighter pilot. He flew Spitfires in the
Canadian Air Force and later flew a P-47 in
the US Air Force. He was awarded the
Distinguished Flying Cross and the Air
Medal with one oak leaf cluster.
In 1943, Captain Boehle’s P-47 was shot
down over the English Channel, where he
spent a couple of days in a raft before being
rescued. When he returned to civilian life,
Vernon wasn’t too active in modeling; this is
according to Robert Cahill, who prepared
Vernon’s biography for the AMA.
In recent years we have occasionally seen
the Boehle Giant replicated. Owing to the fact
that it still hasn’t done well in competition, its
appearance at contests has been rare and sort
of a novelty.
In addition, current Texaco rules restrict
the Giant’s probability of success; the rules
limit the fuel allotment (based on aircraft
weight) to 7 pounds. The model can weigh
more than 7 pounds, but the maximum
allotment stops there.
However, the introduction of more
powerful engines and electric power could
change things. Glen Poole and Dave Harding
recently took Boehle Giants to the Society of
Antique Modelers’ SAM Champs. The two
haven’t proven the airplanes yet, but we
could see more of them at contests if the
electric rules are friendlier to the Giant.
Each year, the SAM Champs manager
selects one or more one-time, special-event
airplanes. The choice is often based on the
fact that a particular design is rarely seen on
flying fields, especially in competition. The
reason many of these models are seldom seen
is because they are (I don’t know how else to
say it) ugly.
But, like beauty, ugly is in the eye of the
beholder. I’ll let you judge the appearance of
the Wedgy, which was one of the selections
for the 2008 SAM Champs.
Seven Wedgys were built and flown in
2008, and all were the original size of just
278 square inches. The numbers of specialevent
models are usually small because they
aren’t always pleasing to the eye, they are
often less competitive, and they are featured
150 MODEL AVIATION
for only the one competition.
Power choice was optional, with no clear
favorite. Bob King won the event with an
O.S. .10 glow engine, followed by Glen
Poole using a Speed 400 electric motor, and
Dan Schneider using an Elfin diesel.
However, not all special-event designs
are ugly or built in small numbers. In 2006,
the Fokker D.VIII was one selection for RC.
That visually appealing little aircraft
produced a possible record turnout for the
event with 15 entries.
Several other D.VIIIs were built, but they
were flown only in local events since their
owners didn’t make it to the Champs. Earl
Stahl, the original designer of the model,
was at the contest, and he received celebrity
treatment.
Troubleshooting engine problems carries
unique challenges for Old-Timer (OT) fliers
who use spark-ignition power plants. It is
often frustrating and interesting at the same
time.
In the previous column, I mentioned that
you can cook a spark coil by leaving it
activated with points closed and the engine
not running. Fortunately, this doesn’t always
happen, as many FF Texaco fliers often
prove.
In Texaco events, the engine shuts itself
down after running out of the measured
amount of fuel. An RC flier can then switch
the system off using the throttle control—as
long as that person remembers, and as long
as the model isn’t so high that he or she can’t
hear it shut down. But what does the FF flier
do?
I asked SAM FF champ Larry Davidson
how most of the fliers prevent coil
meltdown. He said that he has successfully
ignored the possibility and has yet to cook a
coil. Either his engines stop with the points
open or/and the coils are rugged enough to
survive. Larry added that a few FFers are
concerned enough to use shutoff systems,
but he wasn’t up on the latest details.
There may be increased interest in
shutoff systems now that the only new coils
available are lighter in weight (which is
good) but might be less rugged when left on
but not firing for several minutes.
The problem the FF flier faces is how to
shut down shortly after an engine run that is
not precisely known beforehand. A simple
method is to use the conventional timer set
to switch off roughly a minute after the
tested average run time. Using a magneto
would solve the problem, but the
competition rules keep things simple by
allowing only breaker-point-operated
systems driving a battery and coil.
A circuit was published years ago that
consisted of a transistorized ignition-point
trigger with an added feature for automatic
shutoff whenever the breaker points stopped
operating in the closed position. My friend,
the late Ron Doig, built one of the units and
soon reported an unusual problem.
He claimed that his Super Cyclone
engine could no longer be hand-started on
the system but would start fine using a
starter. At the same time, his Ohlsson .60
would start by hand using the same unit.
Since this sounded weird, curious,
interesting, and improbable, I spent part of
an afternoon at Ron’s house while we did
some troubleshooting. Before we began, I
needed to be convinced that Ron’s
assessment was correct and repeatable; it
was.
So the question was, “What difference
did the shutoff unit see between the two
engines?” We cogitated for a while until an
“Aha!” light bulb appeared over our heads.
The only difference the unit could
recognize was dwell. The electronic unit was
set to switch off too quickly with points
closed. You couldn’t crank the Super Cyke
fast enough by hand to keep the unit from
switching itself off. Using a starter, there
was no shutdown because the points were
moving faster. But why could the Ohlsson
be hand-started while the Super Cyke
couldn’t?
We measured and compared dwell on the
two engines, and, as we suspected, the
Ohlsson had many degrees less dwell than
the Super Cyke, so its “points closed” period
was much shorter. As usual, identifying the
problem provided most of the solution.
I forget what Ron did to fix things, but
two possibilities arose. Increasing the
Cyclone’s point gap would decrease the
dwell period some, but possibly not enough.
A more permanent solution would have been
to change the value of a resistor or some
other component to slow the shutoff feature.
Four-stroke engines offer better fuel
economy and are often customized for
Texaco use by adding a set of breaker points
and running them as spark-ignition engines.
This is legal and can allow use of gasoline
fuels, which will run longer than alcoholbased
glow fuel employing the same
measured quantity.
An engine columnist published a letter
from a fellow who had had his four-stroke
converted but could no longer start it by
hand. Suggestions were offered, but I
suspected that the writer may have left out a
significant fact.
Many of us, myself included, find fourstroke
glow engines easier to start by
flipping the propeller backward, as do the
CL Combat and Rat Race fliers. You prime
the engine and flip the propeller backward
lightly, letting your gloved finger slip off the
propeller. The engine fires and kicks off
running in the forward direction.
I suspect that the letter writer was trying
to use that backward-flipping procedure on
his four-stroke. That doesn’t work with
spark ignition, because the spark timing gets
totally confused by it and refuses to
cooperate.
Thanks to Steve Roselle, who bailed me out
by preparing the pictures for this month’s
column when my computer crashed exactly
in accordance with Murphy’s Law: just
before I was leaving on a trip and just before
the issue deadline. MA
02sig5.QXD 12/22/08 11:53 AM Page 150