OUR prototype parade features this month a car which is a "natural" for a Jetex scale model, and a little juggling with scales produced the fact that a 1/20 scale model would exactly fit the augmenter tube sold for the Jetex 50 and, further, that a scale hatch would enable adequate motor access, so that the model could be an exact facsimile of the full-size car, externally at least.
Full-size plans for the model are printed overleaf; full details of the prototype are given on page 233. Two 1 in. x 1 1/2 in. x 12 in. balsa blocks, four wheels, a cockpit cover, and scrap balsa and wire comprise the total materials list. so for a few pence and a few hours you can produce a working model to exhibition standards.
Tack-cement the two blocks together, trace on the profile shape and fretsaw out. Trace the plan view and wield the saw once more. Carve to outside shape with a sharp knife and glasspaper, finishing off except for a final sanding. Now separate the blocks and hollow to the wall-thickness shown--modeller's or lino-cutting gouges are ideal, and a set costs about 28. 6d, Chip out only small pieces at a time, and finish with long light cuts and a little glass papering. When the fit is satisfactory, line the interior with scrap gauze bandage around the intake area, and cement the shells together. The augmenter tube should be clamped into place between the shells, which, of course, makes it a permanent fixture, Lightly sand the exterior and cut the hatch; install the 1/4 in. motor mount and clip, lining the motor up carefully.
Cut the "wings" to shape. cut out wheel wells, and sand to section, also the fin. Fit rear and front axles. cementing thoroughly--the wheels must be added to the rear axle before cementing the wings in place. Make the wheel covers, as in the detail sketch, and add the fairings, etc., for the front axle. Add oil coolers. Apply two or three coats of sanding sealer, rubbing down carefully, and the finish coat of white. One coat of Valspar proved excellent on our model.
Add remaining details and colour items; a 1/72nd aircraft cockpit cover (Gloster Javelin pattern) completes the model. The scale size wheels are I 3/4 in. diameter, and suitable ones are available; we had trouble locating the right size in the time at our disposal and so fitted 1 1/2 in., which do not look grossly out of scale. The centres are silver doped and the finning suggested with a mapping pen.
The lighter the model the better will be its performance--ours weighed just 1 3/4 ozs. ready to go and touched about 20 m.p.h. on a 6 ft. line. Adjust the bridle to obtain correct tracking---with the single tether point shown in the pictures ours toed out at the beginning of the run and in towards the end. The two-point attachment cured this.
If you aren't a Jetex fan. it should be quite possible to fit a small electric motor driving the rear wheels, carrying batteries in the body.