Corky (oz2937)

About this Plan

Corky. All sheet biplane model. Free flight sport design, for Cox Pee Wee .020 power.

Quote: "Wonderful combination sport flyer and biplane - to us this is irresistable and must be to every free flighter.

A biplane has a certain, indefinable quality which most modelers find irresistible. In designing Corky the basic idea was to produce a model with the classic lines of the modern home-built biplane, and one which would still be a practical, easy to build sport flyer. All-balsa construction results in a rugged, long-lasting model and makes those beautiful ellipses possible with a minimum of building time.

I regret to say that the original recently took off cross country and is now resting deep in some very thick woods. So be sure you know how much fuel is left in the tank!

Begin construction with the wings. The upper and lower are alike in wood size and construction, and differ only in area and dihedral. If you are not lucky enough to find a sheet of 3/32 balsa of the required width for the upper wing, you must splice two sheets of obtain the 5 inch cord. Leave each wing in one piece until you are ready to add the dihedral. Cement the spruce leading edge to each wing blank. This leading edge should not be omitted as it adds greatly to the durability of the model. Using a ball point pen, mark the tip out-lines and rib locations and cut wings to shape. Carve and sand to an airfoil cross-section but don't try for feather-thin trailing edges.

The eight ribs of each wing are cut from hard 1/8 sheet. Turn the wings upside down on your worktable and cement only the trailing edge of each rib in place. All of them should now be standing up off the wing at the same angle. When dry, apply cement to the temainder of each rib, turn the wings right side up, and pin the sheeting down to top of rib. Leave the wings pinned from eight to ten hours. Now trim off the trailing edge of the tip ribs and sand the bottom to form a straight line, joining the leading and trailing edges. Cut the wings apart, taking care to get the correct amount of sweep-back on the upper wing. Bevel the cut edges until you obtain the correct dihedral angle. Place one panel fiat on the worktable and block the other to twice the required dihedral, or 3 in. This is the same for both wings but since the lower wing is shorter, it will have greater dihedral. To complete the wings, glue 1/32 plywood tabs beneath the trailing edge of each wing.

The rudder and stabilizer require no instruction; simply cut to outline and sand to an airfoil shape.

Cut two identical fuselage side patterns from 3/32 sheet and mark off locations of the formers. Make sure that the cut-out for the lower wing fits the top wing contour perfectly, Out the firewall and formers and glue formers A, B, C and D to one fuselage side, checking to be sure that they are at right angles. Now add the other side, and when dry install the firewall, cement rear of sides together, and add formers E and F. When installing the firewall, cheek the fuselage top view to get the correct amount of right thrust.

Bend the 1/16 wire wing supports to the shape shown on the plan. Both the from and rear wing supports are identical except that the rear one is 5/16 shorter to give the correct incidence. Bind them to the 1/16 plywood plates with copper wire, and solder (thread and glue may be substituted). After installing the wing supports in the fuselage, glue the 1/2 in soft balsa fuselage top in place and carve to shape..."

Update 05/02/2014: Replaced this with a clearer copy, thanks to JJ.

Supplementary file notes

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