CO2 Sporty (oz3121)

About this Plan

CO2 Sporty. A reduced-size version of the original 1950 Jack Humphrey Sporty (oz338) biplane design, here for CO2 power.

Quote: "The CO2 Spoty makes a very attractive 'fun' model. Mine flew very well, both indoors and out, for about two years until it came to grief in the top of the tallest oak tree in West Somerset. This was on one of the few fine days in the early summer of 1985. The week before Christmas, a customer came into my shop bearing a battered fuselage which had been taken out of a hedge by a gamekeeper. The model must have blown out of the tree when the wing bands gave way. Luckily, the Telco motor seems as good as ever in spite of the heavy rain we had last summer.

The pylon on this model may look a little flimsy, being only 3/32 sheet, but it has never given any trouble. The front did split on one occasion when the model hit a wall rather hard, but it was held together by the wing retaining wire, and only required a spot of cyano to effect a permanent repair.

Let's build. Fuselage. Build two sides over the plan in the usual manner. The front assembly of 1/32 in sheet and x 1/16 in diagonals are best put together before being incorporated into the sides proper. The cut-out for the lower wing is most easily done with the aid of a rib template after removal of the sides from the plan.

Make the front former by gluing the 1/16 in sheet F1 pieces to the back of the 1/32in ply. Join the two sides with this and F3. Make up the pylon, fit between the two formers, then add the F2 pieces and 1/16 in sq decking supports. Pull the sides in and glue together at rear, then fit top and bottom formers, and 1/16 in sq stringers on top, bottom, and sides.

The forward top decking is then cut to shape and glued on. I find a contact adhesive such as Evo-Stik best for this as no pins are necessary, but you do have to get the sheet in the right place first time! In this case it's easy, as the top of the sheet can be lined up with the pylon, pressed onto the 1/16 in sq support, then pressed round the formers.

Add the motor mount, which is a lamination of balsa and 1/32 in ply, to the front of F1, then build the cowl round this using 3/32 in balsa sides and soft 3/,in. top. The undercarriage is then epoxied between the cowl sides. Finish the fuselage by adding wing platform, dowels, top wing retaining hooks, and tail skid. The wing hooks, being epoxied into the top of the pylon, help stiffen this structure..."

Direct submission to Outerzone.

Quote: "Here is JS Russell's CO2 Sporty, a 3/5 version of Jack Humphreys' original design."

Supplementary file notes

Article text, 1 page. Thanks to Algy2.

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