Time to mount the cowl.

Today I was planning on getting started working on mounting the cowl. In order to do that, the wings have to be on. So it was time to rearrange the shop yet again and mount the wings.

First up is rearrange the workshop to get the fuselage in the proper location for mounting the wings. Then it was the usual goat rope to mount the wings. Luckily Kevin was around to help. “Up, down, forward aft, inboard, outboard.” I have taken the wings off and put them back on enough times already to have somewhat figured it out.

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Both wings mounted, time to fit the cowl.

I got the cowls out and started fiddling with them. As with most my experiences, when trying to fit pre-fab parts to a homebuilt, they don’t fit. The cowl would not fit around the cylinders or the starter ring gear. There is supposed to be at least 1/2 inch clearance around the engine as it vibrates relative to the airframe. I am putting in a O-360 Lycoming, more power than what the plans call for. It is also, shockingly, larger. As they say, “There’s your problem.”

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Lots of head scratching ensues. My brain gears were grinding audibly while trying to come up with a quick and easy way to modify the cowl. I came up with two ideas, but they only invited more head scratching. Then I was resigned to the fact that I would have to build my own cowl. Man that can be a lot of work. Time to get out the big guns.

So I made some forum posts and sent some emails to some of the people who have been down this road long before I. The suggestions were helpful. Consensus came to be that I should cut the cylinder blisters off the top cowl and shape some of my own with proper clearances around the engine.

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While consulting with James, he reiterated that this is the proper way to proceed. He also suggested that this is the time to lengthen the cowl to clean up the airflow into the prop. An added advantage is that the cylinder blisters as they are on the pre-fab cowl are ugly and relatively draggy, so I can up the ramp appeal at the same time.  Thanks James for all the help with how to proceed.

In order to do these modifications, it makes sense to go ahead and purchase the prop extension so I have an accurate reference for where the prop and spinner will be. The plan is to mount the extension with a plywood template that represents the spinner and flow guide. This way I can ensure proper clearance on these parts as well as know how far aft to extend the cowl. A quick call to Saber Manufacturing and the prop extension is on the way.

Stay tuned for progress on Cowl Modification.

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