Rotec’s Radial Engines
Radials for modern flying
BY TIM KERN
SOME DAY, AFTER THE debate is settled over whether liquid or air
cooling is better, pilots and mechanics will decide on the best layout
for a piston engine. Advocates of opposed, V, inline, rotary, and
radial engines continue the debate that, greatly simplified, boils
down to these views: flat (opposed) engines have some advantages
in manufacturing simplicity and packaging; radial engines are easier
to cool and can operate longer under partial-failure conditions.
Like so many others in the aviation industry, brothers Paul and
Matthew Chernikeeff of Australia came to their positions through
model airplanes. As they built larger models, realistic engines
became harder to find, and realism forced then 28-year-old backyard
engineer Paul to design and build a 350-cc (40-by- 40 mm bore and
stroke), seven-cylinder radial engine intended to power one of Paul’s
large-scale Gee Bee racers. Built by hand in Paul’s spare time,
Matthew noted, “The engine became so precious to Paul that it
never left the test stand. It still runs like a top today!” (Before you
ask, the model engines are not being produced and are not available
to customers.)
No matter the size of the engine, the concepts don’t change, and
the thought of building a full-size airplane engine slowly took root.
“The engine actually worked better as it was scaled up,” Paul said.
The resulting seven-cylinder engine (now a full-size 80-by- 80 mm)
first ran in September 2000 and made its
first flight on the nose of a Slepçev Storch
late that year.
By 2006, the market’s acceptance of the
seven-cylinder R2800 and customer
demand required the more complicated
nine-cylinder R3600. (In days of yore,
“R-2800” conjured images of Pratt &
Whitney’s twin-row, 18-cylinder, 2,000-hp,
2,800-cubic-inch engine. The Rotec R2800
is a 2,800-cubic-centimeter engine. The
R3600 is also “metric.” Think 171 and 220
cubic inches, respectively.)
The modern R2800 is a planetary-geared
(3-to- 2 ratio) seven-cylinder, two-valve,
four-stroke jewel that makes a claimed 110
hp at 3700 crankshaft rpm and burns less
than 6 gallons per hour (gph) at cruise.
Weighing in at 225 pounds (dry and complete with accessories), it is light-sport
aircraft eligible and sits at the high end of
the power-to-weight curve for the class. The
