Glow plugs had only been available for slightly more than a year,
and no designed-for-glow engines had yet appeared on hobby-shop
shelves. FF modeling had slumped, CL was just beginning to hit its
stride, and RC remained a distant hope for the future.
Then near Christmas in 1948, K&B’s incredibly tiny Infant
appeared. At .020 cu. in., it was one-fifth the displacement of the
then-smallest model engines on the market: the .097 Super Atom
and the Arden .099.
The Infant was never intended to be a high-revving powerhouse.
Its designer meant it to be a substitute for rubber power or the OK
CO2 motor—for flying small tissue-covered FF models from city
parks and school yards. But somehow the little Infant never quite
caught on.
However, other model-engine men were working on the same
idea. The newly developed glow plug made it relatively easy to
develop small-size model engines. That process was greatly aided
by Ray Arden’s “360-degree porting” and baffleless pistons. In
Southern California Mel Anderson halved the bore and stroke of his
1937-1940 Baby Cyclone .36 to come up with his new Baby Spitfire
.045.
At the same time, across the country in Herkimer, New York,
Charlie Brebeck created the OK Cub .049. As was the Baby Spitfire
the first Cub was
designed using welltried,
long-stroke
spark-ignition
geometry.
Charlie chose his
Cub’s displacement
to be half that of the
Arden .099—and
Has the 1/2A golden era come to an end?
Also included in this column:
• Last chance for CO2 motors
• Odd malfunctions and their fixes
October 2007 113
The Engine Shop Joe Wagner | [email protected]
Until 1948 the smallest model engines on the US market were .099s,
such as the Arden (L). At year’s end came K&B’s Infant .020 (R).
Several once super-popular .049-size engines: Cub, Wasp, Atwood, Fox, Royal Baby Spitfire, Tornado, Wen-Mac, Testors.
RECENT E-MAIL from a reader alerted me that a major era in
aeromodeling may be coming to an end. In the past several years 1/2A
glow engines have gradually but relentlessly become less popular.
The 1/2As were once the mainstay of the model-airplane business.
They arrived at exactly the right time, too. When the first .049
engines were released late in the 1940s, the model-and-hobby
industry was in a serious downturn. That held especially true for
model power plants.
10sig4.QXD 8/22/07 12:52 PM Page 113
114 MODEL AVIATION
A few of the many Cox .049s: original 1952 Space Bug, Babe
Bee, Killer Bee, Black Widow, Texaco, Dragonfly, Golden Bee,
“Product Engine,” Tee Dee.
CO2 motors such as these Browns, Gasparins, and G-Mots are
nearly extinct. None are being made, but a few are still for sale.
These .049s are still available: PAW’s RC diesel (L) and Brodak’s
CL glow.
.049 soon became the “magic number” for further 1/2A engine
development. That wasn’t long in coming.
By the early 1950s neighborhood hobby shops across America
thrived on selling 1/2A engines, propellers, fuel, glow plugs, tanks,
and model kits. Other manufacturers climbed aboard the 1/2A
bandwagon, and by 1955 there were 11 American companies
manufacturing no less than 55 different types of 1/2A model
engines. Now none are manufactured here.
The number of 1/2A engine makers peaked in 1955. After that
year, when Roy Cox simplified his original, rather complex .049
engine designs into the Babe Bee, Golden Bee, and Black Widow
(and nearly a dozen other variations on that basic theme), almost all
other 1/2A producers fell by the wayside. OK, K&B, Atwood, and
Wen-Mac kept going for a while in 1/2A engine making, but Cox far
outsold the others.
Pioneer model-engine man Bill Atwood soon went out of
business and joined Cox, for whom he designed the popular frontrotary
Tee Dee line. Eventually Cox stood alone as the sole
manufacturer of .049-size model engines in the USA.
Now Cox has gone all electric, and the US 1/2A model-engine
manufacturing business is no more. That means no spare 1/2A parts
and no factory service.
A few .049-size model engines are still being made overseas.
Brodak Manufacturing markets a Chinese-made .049 glow engine
for FF and CL. It’s a quality product and runs well. You can reach
the company at 100 Park Ave., Carmichaels PA 15320; Web site:
www.brodak.com.
Eric Clutton—“Doctor Diesel”—imports a well-made series
of the British-made PAW .049 (and other sizes of) diesels.
They’re available in FF and RC versions. Contact Eric at 913
Cedar Ln., Tullahoma TN 37388; Tel.: (931) 455-2256; Web site:
www.cafes.net/doctordiesel.
I’ve done a lot of 1/2A RC flying since 1955. I first saw a 1/2A
RC model in action in 1952, watching Dick Schumacher flying
his Liberty Belle. It was powered by a Wasp .049, which he
equipped with an extended intake that had two needle-valve
assemblies: one approximately 1/4 inch above the other.
Those assemblies provided two-speed engine control by
means of a valve operated by a rubber-band-powered escapement.
It worked fine (most of the time), and Dick’s little Liberty Belle
amazed me with its maneuverability.
The Liberty Belle also amazed spectators and judges at the
1952 Nats. When high winds kept the larger RC airplanes
grounded, Dick merrily flew his 1/2A craft. That demonstration
convinced many fliers present that .049 power had untapped
possibilities. I was one of those fliers.
Now electric power has taken over from the 1/2As for small
RC flying. True, e-power’s lack of oily exhaust, quietness, ease
of starting, and lack of vibration are genuine advantages, yet
“piston power” still has a character all its own. Many enginepower
fliers truly enjoy the sound of their power plants.
Glow and diesel model engines can still deliver more brute
horsepower for a longer time per ounce of “system weight” than
electric power. And many model engines have a “personality”
that motors lack. I’ve never seen a motor that exhibits the
“charm” of, say, a Baby Spitfire or the purposeful look of a
redheaded McCoy .049 diesel.
Fortunately for 1/2A lovers, so many of those little power
plants survive that it’s not too hard to keep flying with them.
More than a million OK Cubs were made, and well more than 10
million .049-size Coxes were manufactured.
Yard sales often include those little machines these days, and
even a badly beaten-up specimen can become a useful source of
parts. (The moving parts of most reed-valve Cox .049s are
interchangeable.)
Another once-popular form of model-airplane power has also
become almost extinct: CO2. The Czech companies that made the
best and most popular CO2 motors—G-Mot and Gasparin—have
stopped producing them. (Stefan Gasparin has moved into
engines, and I understand that his new products are excellent.)
However, Southern California’s well-known Black Sheep
Squadron invested in a quantity of the Czech-made CO2s as a
club-funding project and still has some of them for sale. (Some
10sig4.QXD 8/22/07 1:20 PM Page 114
particles, but it also puts the
opening in the most turbulent airflow at the
airplane’s nose.
To see what would happen I made a
“backward-operating” airbleed carburetor,
with its orifice at the rear. That required
the rotating barrel opening to close against
the back wall of its inlet passage.
That carburetor worked as well for me
as the conventional type, and speed control
with it seemed a bit more linear. In any
case, it’s unlikely that my “backward
carburetor” will ever suffer from a grass
seed clogging its airbleed hole.
Another reader reported a pesky
problem with his .60-size RC engine. It ran
perfectly on the test stand, but in the
airplane it would “flame out”
unexpectedly, often during takeoff.
I’ve seen that phenomenon before. It’s
caused by too long of a flex tube to the
clunk inside the fuel tank.
If the end of the clunk can contact the
rear wall of the tank, that will interfere
with fuel flow in maneuvers or during the
bumps and acceleration during takeoff.
Shortening the clunk tubing so that the
clunk end is at least 1/4 inch away from the