So far as I know, it hasn't flown yet, although by now it may have on a
couple of applications (both, again so far as I know, the two-row 8-cyl
300 hp version). One, which may have been shelved, was a good-sized
airship designed as an ECM/ASW platform by Westinghouse and various other
subcontractors. The other came about after Zoche found out how much
money Porsche wanted to rent the all-attitude engine test stand
originally developed for the PFM--at which point they simply crated up an
engine and shipped it off to Walter Extra for installation in an Extra
300.
The engine has gone through various iterations; by now, the ones
you see on the display at OSH are built in production tooling. The basic
line is the 300-hp 8 cyl, 150-hp 4 cyl, and a 70-hp V-twin, all using the
same cylinders, pistons, con rods (with unique big end treatment, all
running on the same crank journal), etc. The 8-cyl weighs 260 lb ready
to run, the 4-cyl about 180 due to the larger proportion of weight in the
irreducible "basic infrastructure" parts (crank and case, etc.). It's a
compound supercharged engine with both mechanical and turbo blowers.
Starting is via compressed air (from a composite flask about the size of
a football), blown into the mechanical supercharger and thus backdriving
the crank via the blower gear train.
What was most impressive on the test stand was, first of all,
starting: there's no perceptible starting process, the engine just goes
---From "at rest" to "running" in about the first 60 deg. of prop blade
travel. In fact, you could start it at full throttle if you wanted. The
other thing that impressed me was its uncanny smoothness (hardly what
you'd expect from a Diesel): this one is a two-stroke, so you get four
power pulses per rev--twice as many as from a conventional 4-cyl engine.
Best SFC is given at around .365, which means that throttled back to 75%
power (a "mere" 112.5 hp), it'll burn about 6.1 US gph of Jet-A (or #2
automotive Diesel) per hour.
The major problem I see in putting one in Europa (assuming it
becomes available) is prop geometry. Since it's a 90-deg 4-cyl radial,
even canted so the cyls are at a 45-degree angle the prop line is several
inches lower w/ respect to the top of the engine than it would be with a
Rotax. It might require a stubby, wide-chord prop to absorb the power.
Alternatively, one might have to cobble up a 1:1 belt-type "non
reduction" drive to get the prop line back up.
Zoche has a Website; http://193.26.97.194/
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