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Rob's REBVAIR Project
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Date:  3-31-2014
Number of Hours:  4.00
Manual Reference:  
Brief Description:  Engine Baffling Part 1

With the cowling largely complete, I can start on the engine baffling. Engine baffling is a critical part of the engine cooling system, directing the airflow coming through the two round air inlets over the cooling fins on the cyclinders. After it passes through the cooling fins, the hot air needs to be drawn (or pushed) out of the engine compartment, through the lower cowling outlet. I am following the approximate dimensions provided by the WW manual, and the outlet to inlet surface area ratio is about 89 / 38 square inches, or just over 2:1. Some Tony Bengelis reference suggests it should be closer to 1.1:1, or 10% larger outlet to inlet sizing, but other sources say these numbers are not always relevant to every cooling design. Of course, you can have too much cooling air enter the compartment, and unnecessarily rob you of forward speed in the process, but ultimately, I feel my best path forward is to follow the examples set forth by WW, who has, at the very least, a track record successfully cooling aircraft of various designs and top speeds.

Image 1 shows a paper template for the front left baffle, of which the most challenging part is the contour of the 5th bearing unit. Transferring to 0.025" stock and the appropriate bends gives the result next to the template.

Image 2 shows the contours around the cylinder and head.
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paper template yields this metal baffle

paper template yields this metal baffle

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fit to the engine

fit to the engine

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