At the airport today I met a fellow devloping a water cooled
lycoming
0-360.
The discussion included the rotary and he liked it for its future
potential saying as others have
that it makes a better aircraft engine than auto engine. His
biggest criticism was poor cooling due to the constant focused
heat
with only "one" combustion
chamber, unlike recip's.
Has this consideration been solved ? overheating.
bd
Never was a real problem. Partly because the "combustion chamber" is
rotating around inside the rotor housing.
Paul Lamar
I do think this is the limiting factor in how much continuous power
you can make with the rotary. With the stock water pump, around 200
HP is probably close to the limit for a two rotor. Grooving the water
jacket helps. Nucleate boiling is taking place at this level and if
you go much higher, the localized boiling turns to an isolating film
on the CC walls and temperatures start skyrocketing.
This problem can be overcome with brute force water pumps like Racing
Beat is doing with the 900 HP 3 rotor, but this is way beyond what
most recreational aircraft builders are prepared to do.
Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com
Nobody really knows because nobody has placed a thermocouple next the
combustion chamber and correlated the temperature data with the
continuos power generated. Not Racing Beat not Power Sport.
Not even Tracy Crook :) What the water does or does not do temperature
wise has absolutely nothing to do with it.
I suspect this particular urban myth got started when oil
used to coke on on the rotor housings long before synthetic
oil was available. Old oil coked around 250 to 300 degrees F.
I have never, ever, in 30 years, seen a rotor housing damaged by this
kind of heat. I suspect that no car racer has seen it either. I have
seen collapsed cast iron rotors from a turbo charged engine but that was
probably caused by a plugged
oil squirter. The water pump on a Lemans four rotor is
no larger than the water pump on a 13B and that engine developed up to
175 HP per rotor. 350 HP for a two rotor ...for the arithmetic
challenged.
I'll believe it when I see the temperature data. It is one
of the things I am going to do with our new temperature data
acquisition system.
I do have a bunch of data on the Continental water cooled aircraft
engines. Continental did do the homework and instrument this part of the
cylinder head. They found the temperature reached 500 degrees within 1
mm of the combustion chamber and felt that was the upper
limit for aluminum. The Mazda rotor housing is lined with steel and
there is a lot more surface area not to mention the combustion chamber
moves dissipating the heat over one third of the rotor housing inner
surface.
Paul Lamar
Something does not seem right about that heat transference cylinder wall
drawing. It shows 290C as the highest temp in the cyl. 290C * 1.8 + 32 =
554 degrees F
If EGT runs 1500F then combustion temp must be higher than 1500F.
Maybe 290C is a typo?
Chuck Dunlap
I think you are right Chuck. That is from Advanced Engine Tech
by H. Heisler. the book is known to have a lot of typo's.
The curve is correct however as it appears in several other
books I have. You can scale the actual value if you consider
the wall at 500 F or 260 C. I just think the artist put
the 290 C in the wrong place. It should be about right for the
wall temp.
Paul Lamar
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