Darwin,
I made one like this from a SJ cowl then made a mold from that after making it fit. Just remember (I didn't) the engine is twisted and lays oddly on the contours of the upper cowling. Also if it is made from the upper, just dropping 1/2" won't make 1/2" clearance on the sides - where it is closest. But - if you make it thin you can drape it over the baffles to get the contour adjusted and flanges marked. Imagine a semi circle with a 1/2" displaced center, it is close on the sides. Mikes comment about the "spacer" should negate any issue and make a smooth layup foundation. Definitely better than what I did.
You will have to add flanges after forming on engine or in cowl.
If you want to make it pretty, smooth, and evenly spaced from the cowling on sides, It might be easier to make on top of the engine like DanH and Pete Howell did. Having done it (myself) the within the cowl, and if you are only making one, I think this will yield less work overall and a more definitive process.
I like the way crabandy took off the baffles and turned them upside down over the plenum cover to make the flanges. Just be sure the twist is accounted for.
Just an opinion, though. Either way works. In cowl, more finishing work, on engine more contour sanding before layups. Maybe a toss up.
There is more experimentation both Andy, and I, tried if you want to know.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
Last edited by BillL : 09-03-2016 at 02:19 PM.
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