Flat (Avipro) vs Round (Bob's Plans) Boot Cowl Shape At STA B?

[John Bickham]

I'm trying to figure out if flat shape that Avipro uses for the rear bulkhead boot cowl shape has some advantages over the plans method of a rounded shape with T3 tubing.

One of the advantages of the Avipro flat shape is no need to shrink the metal of the boot cowl tunnel to fit the rounded shape that Eric describes in his manual. Are there any other advantages or disadvantages of one approach over the other that my simple mind has not considered?? Cooling square inches exhaust, noise, ease of boot cowl tunnel install, etc ?????

I have the option of either approach and trying to determine best one.
DSCF1291.JPG
THIS was just placed in position for my benefit. I'm 99% sure bottom flange faces forward in final installation.

[whee]

I looked into this some and determined there is no functional difference and I didn't care about the cosmetic difference. I put the flat shape made out of tubing on mine.

[swpilot3]

Hi John,

I don't have any meaningful insight about flat vs round. I'm just a kit builder, but I do have some insight on the facing of that flange for anyone who might be wondering like I was.

I called Mark Goldberg a while back about whether the flange should face forward or aft. The manual says it should face forward because it describes the bulkhead being placed behind that station B tubing. However, some kits have the tabs on the front. So, if I understand what Mark was describing, if the tabs are on the front of that tube, then the flange should face aft like your photo. Makes sense for how the tunnel lines up.

But since your scratch building your fuselage, you could put the tabs either way you want.

Bobby

[Mark Goldberg]

It really is not important whether the flanges of that bulkhead face forward or aft. You just have to make it work with what you have. Mark