Spitfire 22 (oz14443)

About this Plan

Spitfire Mk 22. Radio control scale model WWII fighter, for electric power with 600 motor and 3:1 gearbox.

Quote: "Released in March 1945, too late to see action in WWII, the Mk.22 was almost the last of a line that could trace its heritage back through six years of war, during which it flew under a host of flags and fought on several fronts.

During this time, the Spitfire's performance evolved dramatically: from the 1030 bhp Merlin III-engine Mk Ia, it grew into the 2000+ bhp Griffon-engine aircraft whose top speed was 35% greater and which, despite being 40% heavier, climbed 80% faster. Even so, the late bubble-canopied versions retained the Spitfire's essential character in the lines of their elliptical wing and the tapered noses. And that, of course, is what makes the Mk.22 such as splendid subject for modelling.

Faithful Form: Usually, when I've built fun fighters from this era, I've had to increase the tail and fin areas in the interests of stability - I don't see much point in making a model that's built to scale but uncomfortably twitchy to fly. With the Mk22, however, I was able to retain the scale outline as the original itself featured larger tail surfaces than most earlier versions. Having said that, the areas of the elevators and ailerons have been reduced to suit the needs of the model: scale control surfaces would have caught the airflow like proverbial barn doors! For the same reason, I've limited the rudder deflection, although the control surface itself is of scale size.

Wings: After experimenting with built-up structures, I settled on foam construction for the wings, each of which is now made of two foam panels with veneer skins. These, incidentally, are available from the Nexus Plans Service. Also, in arranging for the dihedral to extend from the centre of the fuselage, I've obviated the need for the flat section across the Spitfire's fuselage, all of which should simplify construction.

Begin by joining the two panels that comprise each wing half, checking that the washout is the same for both halves, and then add the 1/4 in false trailing edge. The TE is grooved along its centreline to create a channel for the 14 swg aileron torque rod. At the 'elbow' in the trailing edge, where the inner and outer wing panels join, you can cut the slot for the torque rods using three hacksaw blades taped together.

To avoid the risk of stiction, I chose to run the torque rods in sleeves made from plastic drinking straws of the sort you find on childrens' drink cartons. Mechanically, they're not ideal, but they do the job, especially if you epoxy them securely to bearers set along the sleeves' run; you can either buy these bearers (Flair make them in 14 swg), or you can make your own from pieces of plastic tube. The slight spring in this gauge of torque rod, by the way, doesn't cause any control problems owing to the modest forces on the ailerons.

Attach the 3/8 leading and trailing edges to the wings, and sand them to shape. The last job before joining the wings is to cut out the recess for the servo box..."

Spitfire 22 from RCM&E, December 2003.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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