Old-Timers
Bob Angell | [email protected]
The first really successful gas-powered model
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. 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.
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 U.S. 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 something 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.
Also included in this column:
- Seven Wedgies
- FF ignition worries?
- The four-stroke back flip
Seven Wedgies
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 Wedgie, which was one of the selections for the 2008 SAM Champs.
Seven Wedgies were built and flown in 2008, and all were the original size of just 278 square inches. The numbers of special-event models are usually small because they aren't always pleasing to the eye, they are often less competitive, and they are featured 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.
FF ignition worries?
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 the points closed and the engine not running. Fortunately, this doesn't always happen, as many free-flight (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 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 estimated average run time. Using a magneto would solve the problem, but the competition rules keep things simple by allowing only battery-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 Cyclone fast enough by hand to keep the unit from switching itself off. Using a starter, there was no shutoff because the points were moving faster. But why could the Ohlsson be hand-started while the Super Cyclone 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 Cyclone, 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.
The four-stroke back flip
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 alcohol-based glow fuel when using the same measured quantity.
An engine columnist published a letter from a fellow who 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 four-stroke 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 slightly, 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
Transcribed from original scans by AI. Minor OCR errors may remain.
