Cracow II (oz1786)

About this Plan

Cracow MkII. A 72inch glider model from 1947 June Aeromodeller. Wing area 420 sq in, wt approx 26oz.

Quote: "Cracow Mark II. A high performance 72 in sailplane designed by L George Temple.

THIS highly efficient design by George Temple, whose name needs no introduction to aeromodellers, affords wide scope for that excellence of finish that can be given to sailplanes without undue worry on the score of unwanted weight. This is certainly not a 'pocket-knife' model that can be chipped out in a few casual hours, but demands a degree of care and patience as the whole machine is constructed of ply and hardwoods - in the model aeronautical sense. When finished it is virtually indestructible and should offer very many hours of enjoyable soaring in the summer months.

Fuselage. As usual the fuselage is built first. The circular formers should be cut from ply of the appropriate thickness and carefully slotted to take the stringers. Care at this stage will be amply repaid by smooth contours and well aligned wings. The skid and forward keel is made in one piece and will serve to line up the front formers. After this has set, using a slow drying glue, fit the top and bottom stringer and line up by eye, carefully binding them in place with thread or rubber bands until thoroughly set.

Next add the two side stringers, and then the balance which extend to just aft of the wing fixing only. The underskid and tailblock should next be fixed and then covering with thin sheet may be commenced. This may be done in four pieces with care, but many will prefer to plank with a larger number of narrower strips. Either method is satisfactory. When about two-thirds of the circumference has been so covered and the fuselage is quite stout to handle the wing fixing blocks and the fin structure should be fixed in place. It is worthwhile to fit the fuselage in a temporary cradle on the workbench and carefully line up for this operation, as the whole success of the model depends on these being fixed exactly square. When this has been done continue with the covering and fair in the wing mount with cork as shown on the plan.

The hollowed out nose block should be fitted after rough shaping, and sanded to the flow of the fuselage when fixed in place. A small portion of the covering should be left to enable the securing screws to be driven home. These are necessary as the nose takes most of the shacks in a bad landing.

Tailplane and Fin. Before proceeding to the mainplane it is as well to complete the fin and build the tailplane. This it will be noticed has slight dihedral, a departure now recognised as desirable in high performance design. Beyond ensuring that this dihedral is built in correctly there is nothing tricky in this part of the work..."

Supplementary file notes

Planfile includes article.

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