Oshkosh Engine
Round-Up
The exciting world of aviation powerplants
BY MARINO BORIC
“NOTHING NEW IN THE world of aviation engines” is a phrase I heard
daily during AirVenture 2011. For the occasional lurker that phrase
may be true; however, this attentive observer found many interesting
new suggestions. Some of them are promising, with almost unbelievable performance data. True, the really big names in the engine
business haven’t presented anything really new, being somehow in
hibernation until the final aviation fuel decision is made, but there
was still enough fine-tuning and exciting new stuff around in the
smaller, less stylish, modest booths.
DUKE ENGINES
This seems to be one of the most promising new internal combustion engine proposals on the market today. The engine built and
designed by New Zealand’s Duke Engines seems to fit very well
in the aviation environment with its round body measuring
only 11. 6 inches in diameter and 17. 3 inches long. Duke
has two engine versions intended for aviation use that
develop 103 hp and 180 hp. Both engines have five cylinders, have 1.85-liter displacement, and
weigh only 101 pounds. The Model 1
with 103 hp at 3300 rpm is direct-drive; the Model 2 with 180 hp at
6250 rpm needs a gearbox.
The engine consists of five conventional cylinders that are axially (ring
pattern) arranged. The whole cylinder
group rotates counter to crankshaft at 20
percent of crank speed causing pistons to reciprocate at 120 percent of crank speed. A near wave
(sinusoidal) piston motion is achieved using a Z-crank with single
inclined journal and a nutating body attached to all connecting rods.
Rima
Four-stroke porting and valve function is
achieved using sliding seals between the
rotating cylinder group and a flat non-rotat-ing ported surface (cylinder head). That
means that the rotating cylinders move
behind openings and the spark plugs in the
cylinder head.
According to the manufacturer, the
engines have much lower vibration levels
than conventional four-stroke engines and
are suitable for spark or compression ignition (gasoline and diesel cycle ignition).
They are able to “digest” conventional and
alternative fuels.
RIMA
This Brazilian manufacturer—known
for decades in the automotive field—
presented two new aviation
engines at AirVenture
Oshkosh 2011. Both are
based on the well-
known air-cooled
Volkswagen engine (Rima
has manufactured more
than 200,000 of them) that
are adapted for aviation, using the
knowledge of Brazilian universities
and advanced materials. The former car
engine was adapted in design (adding a pro-
peller bearing) and material (engine
