I am sure that Felix Wankel and all other early adopters including
Mazda would have had no idea that 650 HP would be extracted out of a
200 pound, two rotor, Mazda engine.
One thing has become crystal clear. Spark plug cooling is a major
issue in high HP Wankel's. Jim Mederer has done wonders in addressing
this issue. However the time has come to rethink the cooling system
to make it better.
This is the way I would do it. Put the cold water in the centre
housing near the spark plugs. Let it flow fore and aft and come out
of the centre housing on the other side.
The center housing has another job and that is scavenging the hot
cooling oil out of both rotors.
The easiest way to do that is run the engine plugs up and rearrange
the oil drain backs. For an aircraft that makes a lot of sense. That
way the hot water, hot oil and the exhaust comes out the bottom of
the centre housing.
The turbo can also be under the engine. Fuselages are higher than
they are wide because sitting people are higher than they are wide.
This concept not done yet. I have a lot more work to do when I find
some spare time from the ignition biz.
Thanks to Larry Childs for the excellent rotor housing 3D's.
Paul Lamar
BTW a Super Cub with this engine would set world records for STOL
take off and landing.
Paul, I was reading an article a little while ago, about putting
quantum particles (silver or gold or copper or something) into the
water and vastly improving the thermodynamic efficiency of it (the
water). Something in the region of 50% if I recall correctly, it
could be your answer to your cooling problems. If you think the idea
has merit I'll try and find the article, I think it was in New
Scientist mag. Chris. Hoskins
I would be very interested in that.
Paul Lamar
I seems there are other cooling fluids different to water, somebody
cited in this site a company selling an: 'Evans water free coolant
liquid'
http://www.evanscooling.com however ti was cited also that any
entryof water in the cooling circuit filled with this product may cause
problems.
Water with ethylenglycol (glycol) 40% vv in water will freeze in scales
at -26º C (-14.8º F), and will boil at 106º C (222.8º F); with 50%
glycol vv, it will freeze in scales at -39º C (-38.2º F), and will
boil at 108º C (226.4º F) Heat capacity of Water is 4.18 kJ/(kg.K),
for 2.09 kJ/(kg.k) for Lubricating Oil.
Lubricating Oil has a Thermal Conductivity of 0.13 W/(m.K), versus
0.60 W/(m.K) for Water, I don't know how to translate these figures
into actual suitability as cooling fluid. Lubricating Oil, never
freezes with volume increase, and never boils (below 300º C, at 140º C
it ceases being lubricant, to carbonize), same as Air, that in the end
is true cooling medium; be it fins, radiators, or a tube emitting
steam, heat goes into the air. (exception: outer space) The sale price
of some mixes of Glycol/Water approaches or surpasses that of fuel or of
lubricating oil, and I have no info about the cost of the 'Evans
waterless cooling liquid'.
That oil can be used to cool engines is proved by the fact that Rotors
in Mazda Wankel RCEs are cooled with oil circulating inside; if the
rate of heat uptake, transport an release is good for an ordinary pump
and radiator engine cooling system is something I ignore, regarding
the issue of heat capture inside engine, also several images appeared
here about how to add some 'fins' to the cooling water passages inside
housing to increase the rate of heat transfer from engine to cooling
liquid.
Regarding positioning of fan, data from Sachs about their forced air
cooled engines pointed that it's more efficacious, and takes less
power, placing the fan in a 'push' action, blowing air through the
radiator or fins downstream, behind in the air flow, than placing it
as suction mean, aspirating air from behind the fins or the radiator,
it makes sense, as a fan working behind the heat source will work on
heated air, having less density, and with reduced air movement
efficiency,on the other side, if you put the fan in front of radiator,
blowing air towards it, the fan core or the electric engine moving it
will be a barrier for the air flow, and also will act as an screen in
producing a section of radiator where little or noflow of air arrives,
in cars, they say during more than 95% of operation, a fanblowing air
to or through radiator is not necessary, and a fan uses a
noticeableamount of power.
The results in SAE paper 2014-01-2160 in an UEL UAV 300 cc per chamber
air cooled Wankel with the addition of Heat Pipes are so impressive,
that I wonder why nobody has tested yet, as far as it's known, heat
pipes in a Mazda size RCE.As with everything in science, there's nothing
as experimental evidence to make the right choice, any comment or data
will be greatly appreciated.
Thanks, have a nice season, best regards,
+ salut Jose Gros-Aymerich Madrid, Spain
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