How do you adequately cool a 4 rotor? You'd need to re-direct the
coolant flow in some way, right?
Brian Trubee
For a car it is not a problem due to the low duty cycle. What Mazda did
with the Lemans four
rotor was feed water into the center housing and let it flow forwards
and back in an attempt
to cool the rotors uniformly. That is why the rear rotor always runs
hotter in the
13B.
NSU, Mercedes Benz and Curtiss Wright in their four rotor engines used
an external water manifold for parallel cooling.
Difficult to do with Mazda axial flow cooling. Easy to do with NSU type
radial flow
cooling. Parallel cooling has been and still is used for heavy duty
liquid
cooled engines right from the start. Everett Hatch took a stab at it
with the 13B and gave up.
Paul Lamar
The ultimate aluminum center housing would be designed with parallel
cooling
in mind. In other words there would be a split so water would go fore and
aft.
Paul Lamar
Alan Tolle wrote:
Just a small correction regarding Everett Hatch and parallel cooling. He
did use parallel cooling on the 180 Superlight engine for which he made his
own aluminum end and center housings. This engine also incorporated a belt
driven water pump and an e-shaft driven two stage oil pump, one stage for
engine oil pressure and the other for oil scavenge. Being dry oil sump it
was mounted plugs up and cooling water was introduced through a
distribution plate mounted around the spark plugs. He gave up on the
engine (but not on parallel cooling) due to the fact that the cost to the
customer would have simply been more than the market would bear. The
engine was just far too exotic (read expensive) for the homebuilder market.
I should correct one other comment made recently on these pages. It was
written that "Everett Hatch abandoned the use of planetary gears due to his
fear of torsional resonance." Nothing could be further from the truth.
Everett abandoned the use of planetary gears because there was no way to
adequately lubricate the needle bearings on which the automotive planetary
gears ride. As the result of his consultation with planetary gear experts
in the automotive field (both Ford and GM) he concluded that for aircraft
application the planetary gears should ride on plain (not needle) bearings
and that lubrication had to be pressure down the shaft (not splash.) Time
will tell on this, but I will bet that in the end Everett Hatch will be
correct.
Now, I know that today most rotary engines are using planetary gears,
because that is what is available at a reasonable price. There have been
some problems, but to date actual critical flying time data for the rotary
engined aircraft fleet (hours accumulated between repairs) is pretty much
an unknown. The oft made claim that "thousands of hours have been flown by
rotary engined aircraft" fails to consider the issue of how often things
break in the course of those hours.
Finally, it strikes me that most of rotary engined aircraft pilots I know
and visit with at the fly in events (the people with actual hands on
experience) no longer contribute to these pages. This is unfortunate,
because there are some really bright people out there who are making the
rotary engine work in aircraft application. Discussion among current
builders is fine, but it would be nice to hear the "voice of experience"
occasionally.
Alan Tolle
Some do and some don't. These pages are mainly designed to get
people going and the vast overwhelming majority are silent.
Paul Lamar
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