Paul,

  Attached is a picture of a crossflow radiator like I was considering.
  Notice that the tanks are on the ends rather than on top/bottom
  configuration.  This one is for a Lincoln (model not specified).  Here are
  the specs per the Summit Racing web site.  Something around this size
  could
  be made to fit in a fore/aft configuration inside my Lancair cowl.  I was
  thinking of converting two of these into a cross-counterflow design.  Two
  of
  these would give 2.7 cu. in. of core per hp.  The question is would two 7"
  inlets (77 sq. in.) feed enough air to cool 375 hp?

   Brand

  Proliance Ready
  Rad<http://www.summitracing.com/search/Brand/Proliance-Ready-Rad/
  Manufacturer's Part Number

  431393
  Part Type

  Radiators <http://www.summitracing.com/search/Part-Type/Radiators/
  Product Line

  Proliance Ready-Rad
  Radiators<



 http://www.summitracing.com/search/Brand/Proliance-Ready-Rad/Product-Line/Proliance-Ready-Rad-Radiators/?autoview=SKU

  Summit Racing Part Number

  *PLI-431393*



  Radiator Style

  Crossflow
  Row Quantity

  Single-row
  Radiator Finish

  Natural
  Radiator Material

  Aluminum/Plastic
  Transmission Cooler

  No
  Inlet Location

  Upper driver side
  Inlet Size

  1 1/2 in.
  Outlet Location

  Lower passenger side
  Outlet Size

  1 1/2 in.
  Core Height (in)

  18.375 in.
  Core Thickness (in)

  1.000 in.
  Core Width (in)

  27.500 in.
  Fan Included

  No
  Quantity

  Sold individually.

  With that said, I saw a picture of a turbo-prop Columbia 400 on the EAA
  website today that I really like the looks of the cowl, and very low drag.
  I sure would like to be able to do something like that for my rotary ES.
  The only thing I can think of is to put the radiator on the firewall and
  use
  a wedge shaped plenum.  (You did a sketch like this for a Legacy a while
  back.)  Now back to reality...

  Mark S.

  Looks good. Use two back to back in a counter cross flow configuration
  on the right side of the engine.  I think a single 10 inch diameter inlet
  would work OK if you have a nice set of cowl flaps you can open
  to suck the air out the back side through the right side of the
  cowl.  Keep the oil cooler as is on the other side.

  Pointy noses are over rated as far as drag is concerned :)
  Paul Lamar


  Paul,

  I have a spare cowl which has dual 7" inlets (original cowl has 5.5"
  diameter inlets).  I would like to plumb both sides to the water radiator
  and then add a small chin scoop for the oil cooler.  I calculate the area
  for the two 7" inlets at 77 sq. in.  Assuming adequate exit area, do you
  think that 77 sq in would provide enough cfm to cool 350 hp?  I was told
  that I should have between 20% and 30% inlet area to radiator face area.
  If
  so, then 77 sq in. is not even close.

  Mark S.

  Kind of on the shy side. Also there will be some losses plumbing
  the right side over to the left.
  Here is a suggestion. Use the right intake and the lower center for the
  rad and the left intake for the oil.

  Paul Lamar


  Paul,

  Yes, that would probably work out better, especially for routing the
  plenum.  And it could be sized as necessary.

  Let me ask this.  I've seen some a/c with a cowl flap on top of the cowl,
  just aft of the spinner.  I understand this is a low pressure area,
  especially during climb mode.  I have considered trying that since my
 water
  radiator is directly below this area.  Once up to altitude and into cool
  air, it could be closed.  Any thoughts?

  Mark S.

  That works  for an updraft air cooled engine
  but hard to take advantage of with liquid cooling
  as a lot of stuff like the PSRU gets in the way of the exit
  flow. The internal geometry is just not favorable.
  However it would probably help your current
  configuration as it would lower the entire air pressure
  and temperature in the cowl.

  Here are some CFD's from Peter Garrison. The blue is dynamic
  pressure. At the aft end side of the cowl right in front
  of the wing is an ideal place for a cowl air outlet.
  A large flap there on the side of the cowl would work
  wonders for cooling.

  IMHO right now your rad is being affected by the
  high heat under the cowl as well as some radiation
  from the exhaust. Increaseing the air flow through
  the cowl will reduce the heat the rad is subjected to
  of course.

  It is always better however to duct cool air directly
  to the rad and shield it from internal cowl temperatures.
  A one degree F reduction in temperature the rad is subjected
  to is a one percent improvement in cooling. The reason for
  this is the temperature difference between the cooling air
  and the rad being only 100 F with 200F water temperature. The
  water temperature cannot get much higher than this as it would
  boil. In an air cooled engine with the heads running at 400 F
  the rule of thumb is more like one degree cooling air
  increase is worth  only .3 percent reduction in cooling.

  You need to get some actual static pressure numbers on
  various areas of the cowl using a water manometer. It is possible to
  state  a particular area is high or low static pressure but one needs
  to know how much relative to dynamic pressure.

  Send me the dimensions on the width and height
  of the fire wall and the length of the cowl from firewall to prop flange.
  I'll do some 3D's suggestions of the internal cooling ducting
  Also consider using a 16 inch diameter spinner as that results in more
  cowl volume for internal cooling ducting.

  BTW IMHO with all due respect Peter Garrison missed a point about
  air cooled aircraft engines in that most are designed for down draft
  cooling with the hot exhaust part on the bottom and the cool part
  on the top. Franklin discovered, back in the early
  1930's, that it is best to have cool air go over the
  cool part of the engine first and then the hot part.
  Most downdraft air cooled engines use this configuration.
  This is the same rational used on the counter cross flow
  heat exchanger. It maximizes the average temperature difference
  over the parts to be cooled. The rate of heat transfer is
  directly related to the temperature difference.

  Paul Lamar
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 Paul,

 Peter Garrison's a/c is the one I was thinking of when I sent my previous
 post.  If I understand the pressure graph correctly, the blue shading is
 the
 highest pressure, green is mid point, and red is the lowest pressure.  This
 is where I got the idea that just aft of the spinner would be a good spot
 to
 put a cowl flap.  Airflow should be pretty good in that part of my engine
 compartment as the only thing in that area is the the psru, and the
 radiator
 core is directly below the psru.  Unfortunately, the oil pan is very close
 to the aft half of the radiator, but there's nothing I can do about that.

 I've seen other Lancairs with cowl flaps just aft of the spinner, but I
 suspect those were installed to enhance ground cooling, but that is just a
 guess, it could be they are using updraft cooling similar to Peter
 Garrison.

 I agree that exhaust heat is a big factor.  My current system is shielded
 to
 reduce IR, but the radiant heat is still a big factor.  It is a
 toss-up between finding a muffler that can live behind a rotary, and weight
 and drag.  Not sure what can be done about the radiant heat.  I really
 don't
 want a muffler hanging on the bottom of the airframe, so that restricts my
 options.  The current DNA muffler isn't the quietest muffler around, I
 would
 call it marginal, but it seems to be holding up to the challenge.  The
 problem with it is that it is blocking a good part of the exit air on the
 left tunnel, not good.  Cooling could benefit from enlarging the
 tunnel exit area.

 With that said, I have gathered all of the materials for an inconel
 tangential muffler, but that puts more of the heat into the engine
 compartment.  I plan to build the tangential muffler and install it on the
 p-port engine.  It will have a heat shield, but I don't plan to ceramic
 coat
 it.  Until then, I will have to use what I have.

 Mark S.

 Putting some vents on the top of the cowl behind the spinner won't hurt
 and they will definitely help the heat soak situation as you will get
 air flow through the cowl you are not getting now when stationary.

 There are some small wall vents in Home Depot that will work great.

 I do want to point out the Peter's CFD does not take into consideration
 the rotation of the prop so pressures in the real world might be
 considerable
 different. There is no beating  a water manometer to find out what is
 going on under actual flight conditions. I would love to publish
 some of that data if you can find time to do it.

 Paul Lamar

Paul,

OK, before I start cutting up my cowl, I'll take some manometer readings at
a few places on the upper cowl near the spinner.  If I understand it, one
end of the tube goes to the point where you want to know the pressure, and
the other end is open (referencing cabin pressure).  Or does the other end
hook up to the static port?

Mark S.

You can do it either way. The static port is best as some times
there can be large pressure differences in the cockpit.
Don't forget to use porous foam on the static pressure taps.
Unless of course you would like to measure local velocities
and directions in the region behind the prop which Peter and I
would be highly interested in :) You could also tape on some
tufts just behind the prop as well to get the local flow
directions. A digital cameras with video capabilities mounted
on the dash  would be down right wonderful :)

Here are some suggestions for the side mounted Lincoln rad.
The cheek opening is 8 inches inside diameter with a 16 inch spinner.
This is an RV10 motor mount and nose gear so there will be some
adjustments for your airplane.

Paul Lamar