Tips on trimming the forward end of the cowl?

[Thermos]

Hi all,

I'm a little stuck on how to trim the forward end of the cowl. I've looked at how the Bruces - Hill and Swayze - did it on their websites, but a few questions remain -

What's the purpose of leveling the top cowl? What am I leveling it to? Seems to me that it only fits one way across the top of the fuse - or am I wrong?

Do the forward ends of both the top and bottom cowl get trimmed, or just the lower? If they both get trimmed, what's the reference for trimming the top cowl?

Help!

Dave

[captain_john]

Dave,

Now I know why you needed Bruce's number yesterday. Did he answer your question?

Leveling it means to set it to the spinner height and parallel to the top skin of the fuse... I think? At least that is what it means to me. I suppose that because the cowling has a shape that already matches the fuse, rotating it more than a few degrees would be impossible.

How is it coming along?

Pictures please!

CJ

[bruceh]

Dave,

Are you talking about the overlap on the sides? You want to cut out a nice 1/4" thick circle of plywood about 13" diameter to show how the front end of the cowl will end up against the spinner. Get the middle of the cowl looking similarly circular by sanding down a little at a time whatever is touching and preventing that. There is a bit of extra material on both sides of the inlets to work down. Once you get that done, then put the upper cowling on the airplane and trim back the aft edge until it is flush against the firewall and top skin. Same for the bottom cowl. After those can be put together, then you can find your horizontal line that best fits the top to the bottom from the front to back. I'm probably skipping a million steps here, but that's about how many times you will iterate putting this thing on and off, sanding a little bit here and there, etc.

Bruce

[Thermos]

Bruce - yes, thanks, that's exactly what I was referring to. Following your suggestions, and some tips from Dan Horton on TOS, today I managed to get a good start at a trim line across the front.

John - you want pictures, you got 'em! Took these today -

Spinner primed -



Laying out the trim line -



First cuts on the front trim line -



Center flange -



Intake sides -



A successful day -

[sibriggs]

Looking good Dave, ready to put those Skybolt Fasteners on.

Steve

[captain_john]

Dave, you are doing a great job! Keep up the great work! Let's see when I can get up there and have a peek first​ hand. Lately weather is sketchy at best.

CJ