Schempp-Hirth SHK (oz15021)

About this Plan

Schempp-Hirth SHK. Radio control scale model glider. Wingspan 4250 cm. Scale is 1/4.

Quote (google-translated from the Italian): "Construction: As far as the wing is concerned, I won't go into technical dissertations and advice, because I believe whoever undertakes the construction of a similar wing has half an idea of how to make it. All the dimensions of the wing are shown on the drawing, the only particularity is the round high-strength steel bayonet of 12 mm in diameter; However, I did not define the cutting templates because they were conditioned by the thickness of the covering used.

In this regard, let me just remind you that, since the surface is 90 dm2, the choice of covering will significantly influence the final weight of the model; if you want a thermal machine, I recommend a 1.5 mm balsa covering without adding too many layers of fiber (the thickness of the profiles will guarantee good structural resistance); if, on the other hand, you are looking for efficiency, you can use obece or walnut, providing layers of fiber that slope towards the opening. My wings, covered in obece with various fiber reinforcements and covered in Monokote, with two standard servos, each weigh 1200 g.

The tail planes are curved for the dual reason of lightening the tail as much as possible and to give an extra touch of realism; for their construction I created a special step that reproduces the curvature of the profile in negative (see photo opposite).

The rudders are all mobile and fit into a 5 mm diameter steel bayonet; in the first project I had created an internal movement system reproducing the original, but the play of the various couplings combined with very small lever arms made everything unreliable; for this reason I preferred an external control and a bracket with a notable lever arm to better dampen the inevitable oscillations.

The construction of the fuselage is divided into two distinct moments: construction of the skeleton and its covering. The latter is undoubtedly the most delicate part of the work because it requires a lot of calm and attention. To avoid accidental breaking of the cladding, I used 1.5 mm birch plywood for the front panels, while the rear cone is divided into panels of decreasing thickness from 1 to 0.8 mm.

Start by cutting all the plywood pieces that form the skeleton; It is useless to remind you that any imperfection in the profile of a frame will lead to undulations or depressions on the covering. The frames from Fl to F5 must be mounted using the 5 mm birch plywood keel and the 3 mm birch plywood canopy support contour as a reference. The frames from F6 to Fll will be inserted along an aluminum tube..."

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