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Building Tips and technical articles. => Building techniques => Topic started by: Paul Smith on December 21, 2007, 06:33:00 AM

Title: Sheeted foam wing,,,,
Post by: Paul Smith on December 21, 2007, 06:33:00 AM
This goes against certain common thinking, but it seems to be working.  It's a solid-core foam wing, sheeted with 1/16" balsa and assembled with Titebond II.  It has dihedral and a lw wing, so the leadouts will be outdoors.

It starts with foam cores which are imediately glued together at the centre.

Next, the wings are cut off 6" outboard of the centerline, leaving a 12" centre section.

The centre section is then cut twice more to leave a 5/8" gap for the landing gear spar.
Title: Re: Sheeted foam wing,,,,
Post by: Paul Smith on December 21, 2007, 06:39:19 AM
Balsa ribs are added at the tip and the 6" cut, also a half-rib midway between.  These 2.5 ribs give the skins something to glue to, thereby solving the issue of delamination.  Also, a balsa leading edge is added,,,it will later be sanded down to almost nothing.

Skins are fitted with masking tape, and glued, one side at a time, and pressed between the empty husks.  The photo shows a weak first attempt.  My tool box and pit box were added just after the pitcher was snapped.

There is also balsa-to-balsa gluing at the trailing edge.
Title: Some work with the sanding block,,,,
Post by: Paul Smith on December 21, 2007, 08:47:18 AM
Hot tip - sand it outside.

Get fresh air and keep peace in the valley.

The outboard tip is laminated out of the heaviest wood in the shop with some lead tape for good measure.
The inboard has lighter wood and a plate with a couple 2/56 blind nuts for the leadout guide.
Title: Re: Sheeted foam wing,,,,
Post by: john e. holliday on December 21, 2007, 10:01:13 AM
Looks like a lot of work, but, it looks great.  May I inquire what the design of the plane is? DOC Holliday
Title: Consolidated PB-2a
Post by: Paul Smith on December 21, 2007, 11:50:13 AM
This is the design intent.  Hopefully winter will continue long enough for me to finish in MY (model year) ought-eight.

I'm getting into building stuff from the archives out at Selfridge Army Air Field.