Initial RV-10 cowl sanding

I'm working an RV-10 but I suspect it's the same for any RV cowling. I want to ensure this looks correct before committing to any drilling.





The diameter both horizontally and vertically is roughly 13" ... hard to be exact without a straight edge. I do have a bit of a gap to accommodate the later painting and whatnot. The top still protrudes out a bit further than the bottom. I can probably sand a bit more on the inside of the top to get it tighter. Thoughts?

The best way to fit the cowl is to follow the plans. What the plans don't mention will become obvious as you start to fit the top cowling. The bottom goes fairly well.

With the top you will run into numerous interferences and issues mainly around the cowl inlets. Sometimes it is hard to figure out where the problem is, use a piece of paper and slide it around between the top and bottom to locate the tight spot. Trim slowly, it takes a long time to do an epoxy repair.

The cowl glass is actually fairly good, especially if you did a -6 cowl from the 80's. I essentially removed and rebuilt almost the entire inlet area of that one.

Bruce that's a great tip on using a piece of paper. I was putting tape on the bottom to try to identify the rub, but sliding paper sound like it will work better. I'll give it a go tomorrow to try to get things just a bit tighter.

Japanese saw

I used one of these japanese saws on my cowl once it got down to the final touches. It has a very narrow kerf and makes a nice straight, narrow gap. It is useful for the gaps on the sides and front. I also used a piece of thin aluminum as a gauge to get a uniform gap. The size of the gap is actually less important than it's uniformity. A varying gap will draw the eye more than a larger, uniform space.

https://www.harborfreight.com/12-in-flush-cut-saw-62118.html

I tried the paper trick but it seemed to get stuck in the middle of the flange. After some more sanding I decided to try something different. I sprayed the flanges with some left over rattle can paint and then immediately pushed the pieces together. When I took them back apart I saw the areas of rub both on the flanges which were smudged, and on the inside of the top piece which now had paint in those areas. A bit more sanding and now they come together as tight as I'm going to get them.

The next step has me confused....



Seems the inboard edges of the vents at 3.5" and the outboard at 2". What about the corners and the top and bottom parts?