Sporty Forty scaled to 60

This is a project for the experienced builder who knows how to figure things out.  It’s not hard, but I wouldn’t ask a beginner to do it.  The plane is intended for 1.20 4 stroke glow engines, or equivalent.  The following factors should be taken into consideration.

  • Use the RCM Sporty Forty plan, printed at 150%.
  • Bottom sheeting in the aft fuselage is 1/8″.
  • Rib spacing is 4 inches, except in the center.  The four spaces in the middle of each wing are 3 inches.
  • Leading edge is 1/2″ balsa.  Sheeting is 3/32″ balsa.  Spars are 1/4 x 3/8 bass or spruce.
  • The fuselage is built like the Lazy Ace, so refer to that plan to get ideas.  The lower wing saddle is provided, and the rest of the front fuselage area is built from 1/4″ balsa sheet.  The aft fuselage is made with 1/4 x 3/8 spruce or bass longerons, with diagonal truss sticks and vertical members made of firm balsa. Place the bottom longeron so the surface of the 1/8″ bottom sheeting is in the right place.  Add sheeting to accommodate push rod exits.
  • 1/16″ ply forward fuselage doublers are provided.  Use these as a guide for building the fuselage sides.  1/4″ balsa lower chin doublers should be applied to the inside of the 1/16″ doublers.
  • Build a cowl from planks, blocks, fiberglass, paper and glue, etc.  Whatever you want.
  • The top deck is 1/8 balsa sheet.  There is no hatch, so the balsa is applied to the outside of the firewall arch.
  • Chin is 1/4″ balsa.  The outer plywood landing gear plate is applied at bulkhead #1.  The inner landing gear plate goes inside the fuselage on top of the outer one.
  • Bulkheads are 1/8 ply.  Place the front struts directly in front of bulkhead #1.
  • Extra bulkheads are provided for the front top fuselage arch.  Put one in front of each pair of cabane struts, and the smaller one halfway between the firewall and the front struts.
  • Laminate the cabane struts to be 3/8″ thick.  The three layers are different lengths and should be flush at the bottom.  The top looks like stair steps.  The platform on top is in two layers.  The top layer is inside the outer layer of the strut and sits on top of the middle strut layer.  The lower platform lamination is inside the middle strut layer and sits on top of the inner strut layer.
  • Glue blocks to the spars in the top wing for bolts.
  • Aileron ribs are cut vertical at the leading edge.  In this configuration the leading edge stick should be sanded to a V shape.  If you choose to hinge the ailerons at the top, you need to cut the leading edge of the aileron rib to a diagonal.
  • Build the tail from 3/8″ balsa sticks.

If you have any questions, just ask and we’ll discuss it.  The kit has a lot of wood in it, and it looks like a fun project.  If you’re a good builder, you can make this into a really neat blowup of a classic RCM plane.