What have I gotten myself into!: Ch. 7 - Fuselage exterior

Wednesday, December 05, 2012

Ch. 7 - Fuselage exterior - Part 1

Templates and sanding block (1.9 hrs)

The goal of chapter 7 is skinning the exterior of the fuselage, but before I get to that point there is a lot more cutting and sanding to do.

The places that need to be trimmed are: 1) the external juncture between sidewalls, lower longerons, and bottom foam, and 2) the foam adjacent to the top longerons.

In order to accomplish this, the plans contain two life size templates of the required curvatures.

Tracing the template for the bottom of the fuselage

Tracing the template for the top of the fuselage

These need to be transferred to wood, and will be used to check on the progress of the sanding, to make sure the sidewall profile is even along the length of the fuselage, and matches the plans.

Glueing templates with spray adhesive

Bottom template ready

Top template ready

Template use on virtual foam

Templates used by my friend Walter (circa 1983)

Another suggestion on page 7-1 is to obtain a 30” (76 cm) sanding block, and equip it with 36 grit sandpaper. This sanding block is to be used along the longerons to remove enough foam to match the wooden templates.

I decided to make my own by reusing the 2x4 studs from the airplane bottom’s jig, and since 36 grit sandpaper is not very popular at Lowes and Home Depot, I cut a ceramic belt sander roll in half, then glued and stapled it to the sanding block. It's a very tough strip that I already used in the belt sander without any apparent wear, so I don't think it will need replacing too often.

The 2x4 had a very slight bow that I removed with light passes on the belt sander, until it was completely flat.

I'm quite pleased about how it turned out, and if it works well I might scale it down, and make some smaller ones.