Tomboy 48

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Building the model biplane was taking us down a path where we would end up with a most fragile model. One that would probably be seriously damaged at its first crash-landing. So we resolved to put it on the shelf for a while, and to have a go at a bigger and more robust model.

We are lucky to be mentored by a local enthusiast in building and flying model aircraft: Tony Tomlin. He has recommended we build a Tomboy Senior -an electric powered plane with a 48-inch wingspan. The first Tomboy was designed in the 1950's by Vic Smee, and the design was developed by David Boddington some years later. The design has been followed many times by innumerable modellers, and the Tomboy has proved to be a most reliable plane for free flying, for radio control and for competition events.

Tony provided us with balsa wood and ply in various thicknesses -sufficient for our build. We purchased a full-size print of the plans and set up a build base made of cork flooring tiles glued onto a sheet of MDF. A section of the paper plan was taped on to the base, with a layer of cling-film over it, to save the glue sticking the balsa wood to the plans. We used dressmakers' pins to anchor balsa wood strips into place.

By careful measurement of the drawing of the ribs, the shape can be plotted into a CAD (Computer Aided Design) drawing programme. We used LibreCAD. This shape is saved as a DXF, which file can be imported into the laser cutter software.

The wing ribs were laser cut from 2.5mm balsa sheet, taking just a few minutes. The left wing and the right wing are separately assembled, using two strips of hardwood for the leading edge and the centre span, with a tapered balsa strip for the trailing edge. The trailing edge requires notching to accept the ribs. The jointed connection between the rib and the strip contributes to strength.

With the 48 inch wing fully assembled, we turned to building the tailplane and fuselage.