Pirana (oz14632)

About this Plan

Pirana. Radio control slope glider model. Wingspan 140 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, Another small sloper. Ciao, Beppe"

Quote (google-translated from the Italian): "The Pirana is not a model entirely designed by me: I got it 15 years ago from RC Modeler. The original model was called Puranas (oz7832) and was published in the September 1979 issue, in case anyone cares about its origin. A few years ago, in fact, I already frequented the slopes and flew with the Vega of the Aviomodelli or with the Salto of the Wik, two 'large' models even if their wingspan did not exceed 2 and a half meters. Then the models had a more uniform size than we are used to seeing today, they appeared, but were still rarities, the first 'four meters'. The small models were perhaps even rarer, so much so that it was precisely with the Puranas that I won the cup for the smallest model at a meeting in the Val di Fassa.

In Grone, my favorite slope, we still flew from the highest point of Monte Ballerino and we had at our disposal, a stone's throw from the launch point, an overhang of about 700-800 meters which guaranteed, and still does, 'pumps' worthy of the name. From this area I have thrown the Puranas many times performing stunts of all kinds. It then happened that, for various reasons, the drop zone had to be moved. Now yes throws about 200 meters away from the ravine. This path to the Puranas hardly practicable so, being normally the dynamics rather poor and the 'pumps' of the poor things unworthy of the name, the flights became, as I say to Grane, 'technical' and as such not really fun with an aerobatic model.

In the end I nailed down the model which remained there, without protests, until last spring, when, as soon as I had finished rebuilding an Ultimate, pressed by my friend Beni, for a momentary lack of 4 meters (two destroyed in two days in the 'August 93 at the Wasserkuppe, a 'valley floor' and a 'front'), seized by a sudden passion, I set about restructuring.

A very fast job because I only had to provide for the drift reconstruction and the installation of new servos. Fifteen years ago, as there were no mini and micro servos at the time, the Puranas flew with only two servos, one for the ailerons and one for the depth. Now I managed to put four servos in the fuselage: three minis and one micro. Two are for the ailerons, which can therefore also be used as a variable profile. I also added the mobile part controlled by the micro to the rudder, to see if it was possible to perform a few more pirouettes. The profile used is a NACA 1409 both at the attack and at the end. This has a negative twist of about 1°. Don't shiver if you understand profiles, fifteen years ago there was still no talk of Eppler, let alone HQ, RG, SD and others who are now all the rage.

Wanting to design a more modern model for modeling, and having only a superficial knowledge of the characteristics of the many profiles available today, I thought of using a computer program for designing gliders that I got some time ago from a friend. This program allows you to plot the polar of the complete model. It is possible to see how it varies with the variation of any element of the geometry of the project, be this element the wingspan, for example, or the airfoil or the weight or the position of the center of gravity. I chose two different profiles, which in my opinion should be fine and, as a comparison, I added a NACA 2412..."

CAD file

This plan is available for download in CAD format.

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