Un d e r t h e C o w l
are much better now. The German Hirth company
has engines in a multitude of power ratings, both
liquid and air-cooled, with proven redrives. They're
distributed in the United States by Ohio-based Recreational Power Engineering. With Nikasil cylinder
liners and 1,000-hour TBOs, Hirths are available
from 15 to more than 100 hp; with one, two, three,
or four cylinders; with carburetors or fuel injection;
and they carry a one-year warranty against any
defective part and a three-year prorated warranty
on the crankshaft. We'll make it simple: No one offers
as many two-stroke options to the aircraft builder as
does Hirth. www.RecPower.com
MWfly Aeropower: Innovative B22R
MWfly's compact mechanical-lifter OHC, opposed fourcylinder engine has fuel injection, liquid cooling, and a
built-in 1.958-to-1 gear reduction that runs in its own
oil, which is shared by the prop governor. It also has a
multi-piece, counterbalanced, forged crankshaft that
rides on four ball bearing mains; an aluminum case; and
billet pistons in wet steel liners. A small starter, no flywheel, and no clutch keep the 2.2-liter engine's weight
down. These work because the compression ratio of the
engine is automatically reduced to just 5.5-to-1 at low
rpm. (It's 10.5-to-1 at operating speeds.)
Designed for rear or bed mounting and in flight test
since 2006, the Italian-built mogas/avgas 130-hp,
185-pound MWfly B22R was seen at Oshkosh mounted
on a Bushcaddy, represented by the Canadian MWfly
distributor. First deliveries will be available in two to
three months. Price is $18,900, FOB Italy. www.MWfly.
VW Derivatives
Hirth: Two-Strokes of All Sizes
The two-stroke engine dominated ultralight and
light homebuilding in the 1980s, and modern designs
34
Vol.2 N o.9 / September 2013
If you want VW power in your airplane, you can
buy a kit engine from AeroConversions, a complete
engine in several configurations from Great Plains,
a straight conversion by Hummel, or a completely
new, large-capacity (built on proprietary cases)
powerplant from Revmaster. Laid out in the 1930s like
an airplane engine, this Dr. Ferdinand Porsche–designed air-cooled flat four has powered more airplanes than any other automotive derivative. With
power ratings from 60-ish to more than 100 hp, in sizes
from Hummel's 25- to 30-hp 1/2 VW to fours of 1600 cc
to Revmaster's 2.5-plus liters, the venerable VW engine
remains one of the low-cost, reliable alternatives, and
it's available as a kit or complete, basic or all pumped
up. Your choice.