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Old 05-14-2022, 07:24 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,417

Along with the cowl cheek bulkhead flange orientation, there’s another burning question. Do the cowl cheek extensions end at the spar bulkhead as shown in SK-86 or do they extend aft a bit?

I went back into my photo collection and found 15 RV-3s with the cheek extensions ending at or close to the spar bulkhead, 11 ending a short distance aft of that, and 21 ending a long distance aft. Now, without a lot of measuring and calculating, “short” and “long,” as I’m using it here, are probably around 3” and around 6” more or less. And I mean in its most approximate sense. I measured my F-364 pieces and they’d extend aft around a foot, if I didn’t trim them. The front matches the bulkhead curve nicely but the aft end is relatively poorly formed. If I did any trimming, I’d need to rebend the entire part. And if I used them at their current length, I’d need to reform the aft end. You may remember the fun I had bending the bottom aft fuselage skin. Well, these are thinner, a plus, but a much tighter bend, too, which makes it more difficult.

Alternatives are using the RV-4 part, a fiberglass section, which needs to be extended in the front, as a few RV-3s have done or making my own from scratch of fiberglass, as John Nystrom did on his excellent plane. I thought about it and ordered the RV-4 parts from Van’s. These are subject to their wait and ship mode right now and should be in this coming week, but I won’t need to put them on just yet.

I’m supporting the lower cowl with bungees in the back, attached to the cowl by clecoed tabs, and the cowling tool and clamps up front. Here’s the back.

The forward lower cowling has spacers in the cowl tool for spacing.

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