Ugly Twin

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Please specify if you want the glow version or the electric version.  The electric has the firewalls 2″ forward.

Sometimes I change a few things when I make a short kit, but this time I’ve changed a lot of things.  The main difference is that the fuselage and bulkheads are cut from 1/8″ lite ply with tab and notch construction.  The front of the fuselage has a lite ply doubler, and the front of the lite ply doubler has a 1/32″ birch ply tripler, just because the front of the fuselage looks a little flimsy on the plan.  How you put it together will be obvious when you get the parts.

You may recall me mentioning that 3/8″ balsa gets burned up by the laser cutter, so you’ll make the stabilizer and elevator yourself.  The most economical way is to build it out of 3/8 x 3/8 sticks of course.  But if you want to make it out of sheet wood, buy a couple of 3/8 x 3 x 24 balsa sheets.  Edge glue these to make a 6 x 24 sheet.  Then cut 2 inches off to get a 4 inch wide stabilizer and a 2 inch elevator.  If you can’t find 3/8 x 3 x 24, you can use one 3 x 48 sheet, or two 3 x 36.  I’ll provide the stabilizer tips shown on the plan, made from 3/16″ balsa to be laminated to 3/8″.

The plan shows a foam core wing sheeted with 1/16″ balsa.  The short kit includes 25 balsa ribs for a built up wing.  Use 1/4 x 1/4 hard wood spars, and 3/8 balsa leading and trailing edge.  For the top of the wing, add 1/16″ balsa leading edge sheet back to the spars, and about 1″ wide trailing edge sheet, and 1/16″ balsa cap strips.  For the bottom of the wing, use firm sheeting full-chord to the nacelles, or maybe even for the entire main wing section.  Also you should put 1/16″ vertical grain shear webs between the spars.

The main wing is built flat, with 44″ spars.  The outboard sections can be attached with the provided dihedral braces, or just stuck on and reinforced with glass cloth.

Build the nacelles first, then the wing.  Use the nacelles to help place the ribs in the correct position on each side of the nacelles so you can properly fit N3 between a pair of ribs.

On the plan N3 extends from the bottom to the top of the nacelle, and the leading edge of the foam wing has a 7/8″ notch to accommodate N3.  It’s a bad idea to cut through the leading edge on a built up wing, so the short kit has a new part called N3A, which bridges the space between the leading edge and the lower spar.  N3 is installed below N3A as shown in the diagram below.  Attach these parts with epoxy or Titebond and add some 3/16 or 1/4 balsa triangle stock to reinforce all of these joints.