MB 339 (oz14582)

About this Plan

MB 339. Sport scale model for PSS. Wingspan 108 cm.

Note the 'original' drawing here is the CAD zip download (in dwg format). That's the file that Giuseppe sent us, and that is his design, his work. The PDF file you see here is really just a taster, a PDF file in this slot for Oz users who don't have a CAD viewer.

Direct submission to Outerzone.

Quote: "Hi Mary, A small rendition of a well known Italian airplane. It can be flown as a PSS model or with a ,36 c.c. in the nose. Ciao"

Quote (google-translated from the Italian): "PSS stands in English for 'Power Scale Soarer' which freely translated means 'slope glider reproducing aircraft with engines'. One wonders what sense such a thing has.

The answer is very simple: model aircraft makers have always tried to reproduce real planes to scale. To do this, they necessarily had to adapt and modify the original project. Just think of the reproductions in free flight propelled by an elastic motor. Who has ever seen a real Mustang made of strips and covered in paper, a Macchi MC 202 take off with the landing gear pulled out, a Cessna with carabiners on the wingtips to which tethered cables can be attached? Only radio-controlled flight allows you to get as close to the real thing as possible.

You can build a model similar to the prototype in both proportions and surface appearance and then fly it, under control, as the real plane flies. Also in this case, however, some deviation from the original may be required by the type of propulsion.

The flight that comes closest to reality is certainly that of the glider model that reproduces the plane. The propulsion system is the same: self-weight. Gliders can be flown both on the plain, after being towed at high altitude, and on a slope.

Different conditions can be found in slope flight: flight in thermals, in dynamics, in thermodynamics. The best condition for reproduction models is certainly the first, the model that flies in search of the thermal and that exploits it in a spiral, once it has found it, faithfully reproduces the behavior of the glider true and therefore completely satisfies the model maker.

Less similar to reality is the flight in dynamics; it is hardly possible to see a real glider coasting along the slope describing eights in plan to make the most of the current of air that rises along the ground and supports it.

However, flying models in these conditions is very pleasant as long as you have suitable gliders, that is rather compact, easy to handle and discreetly loaded. If the dynamics are good and constant, you can fly for hours making the model whiz in front of your nose and executing acrobatic figures: looping, tonneaux, etc, etc, where they can be most appreciated; that is, at its own height and not far from the slope. In places where the dynamics are really strong, we fly highly loaded models that can reach staggering speeds.

Some model maker must have thought that, by sacrificing speed and efficiency, it was possible to deviate from the usual glider and try some different shape. From here to arriving at the almost exact reproduction, the step was short and thus the PSS category was born.

The country where it has most developed is undoubtedly England, I think I can say for two main reasons, The first is that the British have a great aeronautical culture and model makers, even before model enthusiasts there, I'm from aviation. Second is that England abounds in suitable places for this activity. From the photos that I see published above all in QFI, an English magazine dedicated exclusively to silent flight that I take the liberty of recommending to lovers of the genre, it can be seen that the ideal place to fly is located on the top of a relatively low hill, gently sloping, completely free of obstructions, trees or houses, preferably directly on the sea..."

Supplementary file notes

Atrticle.

CAD file

This plan is available for download in CAD format.

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