Funf (oz15014)

About this Plan

Funf. Radio control sport model, for electric power. Wingspan 1250 mm.

Quote (google-translated from the Italian): "Funf. The ideal model for those who don't take themselves too seriously.

Even though I have been spending my days flying with electric gliders for years now, every now and then I get the desire to do some somersaults again, but knowing very well which 'tunnel' I would be getting myself into, I regularly end up discarding the idea to revisit some of my old acrobatic models in an electric version.

The fundamental reasons for this reluctance are basically two: the first lies in the fact that having definitively abandoned the runways I precluded myself from making a landing worthy of the name and having only uncultivated land at my disposal, concluding each flight with the regular dismantling of the carriage doesn't particularly excite me; the second is that over time my interest in powered flight has faded. So, to explain this 'inelegant' pile of balsa wood I have to take a big step back.

Over a dozen years ago, while towing with my Patchwork (oz15039), a rather strange thing happened to me. I don't remember which model we were developing, the only thing I remember was that the glider (over 5 meters of span) had an incredible sink rate and numerous attempts to improve its performance were of no avail. To have enough time to carry out the trimming I had to tow at very high altitude and, after having unhooked, I was struck by the suspicion that the tow had run into a thermal while the glider inexorably continued its descent. Quickly I went down to the runway to unhook the cable and then went back up to the position where I had intercepted it, I turned off the engine: the tow completed its glide about ten minutes after the glider landed.

That memory made me smile when, rummaging through the balsa wood scraps, I came across a packet of ribs with which I was supposed to make a new Patchwork in electric version. It was inevitable that the rediscovered package of ribs, in addition to triggering an avalanche of memories, stimulated the idea of using them to build something extremely simple and undemanding that could easily twirl with the use of the engine and perhaps even sail like the legendary 'Patch'.

Before I start designing a new model I always look for inspiration in old projects, but this time I even found the work already done: I could use a small fun-fly (the 'FUNF' precisely) made about twenty years ago simply by climbing the dimensions on the string of the new ribs. Models of this type have a somewhat dated concept and are not particularly suited to 3D flight, but they can perform a tight and fast aerobatics like few others.

To adapt it to my flight 'vegetable gardens' and foreseeing only hand launch, I removed the conventional undercarriage and replaced it with a single wheel which has the sole purpose of keeping the engine raised so that it does not fill with earth. To avoid damaging the ailerons lowered in the flaps position, I fixed two carbon rods to the ends of the wing.

From an aesthetic point of view, the final result definitely belongs to the 'horror' genre, but is amply justified by the excellent flight performance and the fact that it only requires about twenty hours of work including covering and various installations.

The construction of the FUNF is so simple that it is within the reach of even those who have never built a balsa structure.

The wings are devoid of terminals to simplify construction as much as possible and also because with such a low aspect ratio their influence would be negligible. I assembled the wing in a few tens of minutes by tracing on a piece of paper just the spacing of the ribs and the position of the spars, thus saving me the time of printing and putting the various sheets together.

The front body and the ribs are made of 2 mm balsa while the spars and the leading edge are made of 5x5 balsa. The ailerons are made from an 8 mm balsa sheet while the servos are mounted in a central position on the wing..."

Direct submission to Outerzone.

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