Seven years after last flying my rotary powered Long Ez I flew it for one
circuit of the traffic pattern at GIF (Winter Haven FL) on Saturday.
Water temps never went higher than 202 F or 190 on the oil. Only problem was
my primary fuel pump breaker tripped at some point. Secondary worked as
planned. I will ground the aircraft until I figure out the problem.

The history on this aircraft is that 7 years ago I had about 70 hours on the
rotary and 10 minutes from my home airport when I had over temp warning and
smelled antifreeze. I reduced power and headed straight to the airport. The
engine continued to run without missing a beat. When I exited the runway I
shut it down and found antifreeze running out all over the ground. The next
day I put water back into engine and found it leaking out of the water pump
weep hole and the exhaust.

At this point I brought the plane home and overhauled the engine and
replaced all seals and water pump. This then turned into additional mods to
the aircraft. This included an extension to the nose and a new cooling
system based on Pauls book. The original cooling system used AC condensers.
It has been a slow process since I still have a day job. I will keep the
group updated as to my status

Mike Perry
Long Ez N981MP
Mazda 13B

Mike was a pioneer in rotary powered aircraft. Thanks for the history Mike.

How was the water getting into the exhaust? Sounds like the o-rings sealing
the rotor housing together failed. Either that or the aluminum rotor housing
shrank in some places after it cooled down from over heating.  They are
known to do that.

Are they  new O rings stock? Stock works great if they are the latest square
silicon. Teflon encapsulated also work great if they are the right size.

The engine will run with out water until it melts the steel  1/8 inch thick
rotor housing liner.

----------------------------------------------------------
Here is a new way of looking at cooling drag.
----------------------------------------------------------
Lets say your cooling opening is 6 inches high and 12 inches wide.
That is half a square foot. Flat plate dynamic pressure is roughly
60 pounds per square foot at 150 MPH. 1/2 square foot = 30 pounds of drag.

If the rad was completely blocked that would be roughly 30 pounds of drag .

Therefor it ALL depends on how easy it is for the air to get through the
rad.

Lets say the rad  was not in there.  Then there would be no cooling drag
except for a little skin friction drag as the air flowed through the duct
and out the open end unimpeded.

150 MPH is 220 foot per second. 30 pounds of drag times
220 fps = 6,600 ft pound second.
I HP is 550 ft pound second.

So it takes 12 HP net from the prop  at 150 mph to over come the flat plate
drag of the totally blocked radiator duct. For every HP needed or used you
will burn a half pound of fuel in one hour. More because the prop is not
100% efficient.

Kays and London addressed this on page 35 of my book when speaking of a good
efficient heat exchanger.

"the resulting core shapes are characterized by large flow frontal area and
short flow lengths for the gas [air] -flow path."

What they mean is a large rad. Long and wide but thin for "short flow
lengths"
This is in the range of 1/2 inch to 3/4 inch thick. This is the low cooling
drag configuration.

The automotive industry is slowly catching on and this Dodge pick up truck
rad is the best example for our use that I have found so far.

We can't stick something like that vertical  in front of the engine as they
do in cars and trucks and did in WW 1 aircraft. Just would not look right
:-)

We have to lay it down under the engine or better yet vertical, parallel
with the side of the cool side of the  cowl. If the duct is a wedge shaped
the flow rate through the core will be uniform through out. It is best to
put the duct between the engine and the rad. The duct insulates the heat
radiated from the hot engine.

BTW this is a huge improvement over the way they did it in WW II with very
thick cores.

Pay attention on this as I am 80 years old and won't live for ever :-)

Paul Lamar

80 years old! You are a youngster.

Milo

Why don't I feel like one? :-)

Paul Lamar


It's a little known fact that, youth is wasted on the young.
Andrew. Campbell

That is so true. The stupid, so called millennial s are voting for a communist :)
Fortunately or unfortunately he did not win the primary.

If he won he would be much easier to beat than Hillary.

The college professors are filling their heads with BS as they can't think for
themselves.

Paul Lamar

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