Boot cowl extension positioning

[Ryan Koeneke]

Hello, I'm trying to figure out the correct positioning of the lower boot cowl extension piece. Specifically what the correct layering process is where the tunnel and the boot cowl extension are connected to the curved former at station B.

My best guess is that the layering process, from top to bottom, should be:

Curved former at station B
Boot cowl extension piece
Tunnel
Forward part of boot cowl sides that connect to the bottom of the 90 degree flanges on the tunnel

However, when I have it in this order, the very end of the outside flanges on the tunnel protrude down and away from the former which makes a gap between the tunnel/forward boot cowl sides and the skin for the boot cowl extension piece (see picture that is an over emphasized example since I left the clecos out to really show where I was talking about (the picture is looking from between the gear legs towards the firewall))

Does anyone have tricks on how to eliminate these gaps between the bottom skins, can someone tell me if the order I have these sheets layered in is incorrect, or can someone tell me if these gaps are normal and you fill them with other materials?

[alaskabearhawk]

Model A from plans, purchased Bearhawk aircraft exhaust tunnel. As an idea, I made a deeper former at B and it helped provide more room for fuel and brake components. YMMV

http://www.mykitlog.com/users/display_log.php?user=yeeeha&project=527&category=3583&log=269462&row=105

[Bcone1381]

What is the dimension of the gap?

Mine was about 1/8", so I applied and waxed some packaging tape as a release agent (nothing sticks to it) to the area where the boot cowl overlaps. Then I put some sealant (RTV high temp) on the boot cowl piece so it sticks to it instead of the mold release. Then I installed the boot cowl and let the RTV set up real good. When I removed it I had a custom seal.

[FFTravism]

The laying matches mine. There is a small gap but the screws will pull it in. Here is my build log for that area. I just did it last month. I had to flatten the end of the tunnel and little and it rolled the overlapping lip to close the gap. Hope this helps.

https://eaabuilderslog.org/?blprojentry&proj=7vGIw4Vtf&e=89h2kVwbt&listcat=&sid=

https://eaabuilderslog.org/?blprojentry&proj=7vGIw4Vtf&e=89h2nNnf6&listcat=&sid=

https://eaabuilderslog.org/?blprojentry&proj=7vGIw4Vtf&e=89vWtUpd4&listcat=&sid=

Travis

[Ryan Koeneke]

Ya, I thought about lightly hammer flattening out the very end of the tunnel but couldn't bring myself to swing a hammer at it lol.

I think the gap is a bit more than 1/8" but as long as others have that same situation I'll see what screws do to suck things up tight and then make a weather seal like Brooks suggested.

I greatly appreciate the extra info from everyone!!!