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Posted

Still working on the oil cooler location but thinking of using a NACA duct on the left cheek cowl to duct air to the oil cooler. I don't want to take cooling air from the cylinders. Lot's of little things to think about.

 David

  • 6 months later...
Posted

Work on cowl mod is beyond the point of return for me now. It's been a busy past year and I'm looking forward to getting the prototype cowling done and on my C. Here's a sneak peak of the work in progress.

David

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  • Like 4
Posted

Still looks like an interesting project. Two thoughts.

Could a NACA duct be used bottom center for the carb inlet with the filter horizontal just below the carb?

Secondly, I've always felt that with the oil cooler inlet below the engine deck that when the cowl flaps are closed to limit airflow the air pressure in the lower cowl would rise somewhat due to the limited outflow. If that happens then the oil cooler differential pressure across the cooler would lessen and it would have less flow for oil cooling. Now with optimized inlets ?? Might be a different story. Just thinking.

Posted

Hi Cliff, I like the thought of NACA duct, but I don't think there would be any room for carb heat ducting or linkage etc. Right now, the oil cooler is staying in the original location because it adds an additional cost and complexity to the STC.

Thanks,

David

Posted

Hmmm, how about a round carb inlet like the top ones that is smooth and faired into the lower middle cowl. Might look better than the square box. Might be attached to the same mounting holes used now.

Someone a long time ago put a sheet metal dam around the bottom and two sides of the square box to capture the slipping air loss trying to gain extra MP. Don't know if it worked but I did see the pictures.

Posted

Hi Cliff, I like the thought of NACA duct, but I don't think there would be any room for carb heat ducting or linkage etc. Right now, the oil cooler is staying in the original location because it adds an additional cost and complexity to the STC.

Thanks,

David

I read a paper about NACA ducts and it said they were overrated and didn't deliver the kind of airflow that they promised. The 747 has huge ones for the pack inlets, but newer Boeings just have a straight ramp like the side of your mooney has. The 737 has a NACA duct for the APU inlet but it also has a wing-shaped diverter piece because the inlet is too small.

Anyways, the piper arrow has a scoop on the side and the outlet extends to the bottom of the cowl to get the airflow through the cooler. A ramp or a big NACA duct on the side ducted to an oil cooler, and the exhaust ducted to the outside of the cowl ought to do it.

  • 1 month later...
Posted

Looks real nice in the pics, how long before flight tests and subsequent speed runs. Looks like you may have one real fast C good luck.

  • Like 1
Posted

Thanks Bonal,

 

I haven't run her wide open yet, but at my normal power settings I seem to get about an extra six to 8 knots and much better cylinder cooling.

 

Bill

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  • Like 3
Posted

Six to eight knots, the heck with panel envy now I got a case of cowling envy. hope you post some real speed results so I can feel even worse. Congrats! :angry:  :D

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