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David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net <http://n4vy.rotaryroster.net/>
http://RotaryRoster.net <http://rotaryroster.net/>

Not necessarily the gear box. They both also had Chevy LS1 engines.
That is a very low duty cycle engine with cast iron crank, rods and
cast pistons. Many Chevy V8 powered experimental aircraft have
crashed in the last twenty years with all kinds of gear boxes.

I had gone to OSH just about every year up until this year
and each year yet another new Chevy V8 project was touted. A year or
two later and they were gone. People get seduced by the promise
of 400 HP when in reality the engine is designed for 40 HP.

I am the last person in the world that will admit an automotive
piston engine is up to aircraft duty cycle requirements. As time goes on
the automotive piston engine is better designed to get as
much cost out as possible and still fit the automotive duty cycle.
Automotive piston engine will catastrophically fail without warning
around 300 hours.

The reason the FAA demands an annual inspection on certified aircraft engines
is to detect incipient exhaust valve failure. The reason a TBO is assigned
by the FAA as experience has shown that particular aircraft engine will go
that long without a major part catastrophically failing other than an exhaust
valve or two.

Here is an article written by Don Sherman a former student of mine.

http://www.rotaryeng.net\DS-smith-art.pdf

* Smithsonian Air & Space magazine article "Power Struggle" by Don
Sherman, January 1997, page 72. Excellent ten page article (with
many pictures) about auto engines in airplanes. A brief history of
all auto engines in airplanes and a more detailed history of the
twenty year, twenty million dollar development of the Chevy V8
based, all aluminum Orenda liquid cooled aircraft engine. At this
time (Jan 1997) and well after the article was written the engine
failed its FAA 150 hour full power certification test due to a
crankshaft problem after 20 years of very expensive development.
It was finally certified in 1998 by Transport Canada.

Extensive changes have been made to the basic Chevy big block engine
including a parallel cooling system with dual coolant pumps as
opposed to the serial cooling system with single pump as typically
found in automotive engines. Parallel cooling systems were
considered to be essential in the 1920's on liquid cooled aircraft
engines.

Engine length is almost everything to a car designer. Engine cooling
compromises are made by simezing the cylinder walls in automotive
engines. Crankshaft life at high continuous power is compromised by
shortening the length, leaving too little room for adequate size
journal fillet radii. In my opinion this engine will not be
successful until it is re-designed from a clean sheet of paper to be
a real aircraft engine. If that happens they might as well go to a
horizontal opposed configuration for lighter weight.

Orenda was in the process of moving the project to Nova Scotia
and injecting another 32 million dollars of mostly Canadian
government money. They where also attempting to market the engine to
the homebuilt market. I did not expect many takers at over $100K per engine.

Several years ago Lancair gave up after spending a lot of money installing
the engine in a special airplane called the Lancair Tigress.
The engine and the Tigress were donated to the EAA museum as
a tax write off.

The Orenda company is now bankrupt.

"Those that fail to learn from history are doomed to repeat it."

It is not for nothing that real aircraft piston engines cost $20,000
and up. You are paying for the best materials and manufacturing techniques
available. They are designed to last 1500 to 2000 hours in aircraft service.

It is just unadulterated luck for us that the Wankel is far more robust
than it needs to be for automotive use and can live in aircraft service.

Paul Lamar

There's nothing in anything I've watched or read about it that states the gearbox failed (to state so would be pure speculation/wishful thinking at this point). Stall seems to be what most indicators point to. Engine/gearbox would only be a contributing factor...

Tom Graziano
                   

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