No way is this cooler going to work.
It will take something 20 times more effective.
Hey Paul,
Has anyone actually found an oil cooler that will work on a 3-rotor?? What about the original stock 20B oil cooler that came in the Cosmo. Its all aluminum, measures 11" X 8-3/4" X 2", and has 15 rows. It must have done an adequate job in the Cosmo at road speeds. What are your thoughts on using the stock oil cooler in the back (pusher) with a second aircraft oil cooler in series in the nose for additional cooling and cabin heat?
Don Mitchell
Plano, Texas
Standard Fixed Gear Velocity (~70%)
Mazda 20B with T. Crook EFI / EI / Redrive
N6VV (Reserved)
There have only been two three rotors flying. Neither one of which was really successful.
Both guys gave up for reasons that had nothing to do with oil cooling per se.
They never got enough hours to really sort out the oil cooling.
Sounds like a good plan if you can tolerate the oil pressure drop in the lines going
forward to the cockpit. Also I would make them out of thick wall
aluminum tubing to be sure they do not burst under the almost
100 PSI oil pressure.
The stock Cosmo oil cooler sounds great. First I have heard of one. How did
you get one? Most people just have the engines.
BTW I cannot emphasize enough the importance of these Stewart Warner
oil cooler .pdf curves at http://www.oilcoolers.com. This is the first real
world data on specific heat exchangers we have seen in the almost four
year history of this newsletter. It proves beyond a shadow of a doubt
that a three and a half inch thick heat exchanger is way too thick for
our applications.
I am surprised the aircraft piston engine builders
are still using them. They are far from optimum and their only saving
grace is the piston engine does not reject all that much heat to the oil.
They also fit well with the piston engine form factor but not
too well with the rotary form factor. Another factor in favor of
the aircraft piston engine is the amount of oil they carry in the
sump. My O-470 230 HP Continental engine has ten quarts of oil
in the sump. It takes a relatively long time to heat up
ten quarts of oil. Probably longer than most climbs.
A large mass of air getting through the exchanger is necessary to carry
away the heat and that means a high pressure differential across
the a too thick core. High pressure differential can only be achieved
by a high dynamic pressure which can only be achieved by high
speeds.
If anybody can read these curves with a pdf viewer and save them
to disk as bit mapped files I would like to hear from you.
Paul Lamar
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