GP1 (oz16550)

About this Plan

GP1. Radio control scale model glider. Wingspan 178 cm.

Vector format plan.

Quote (google-translated): "Vincent Besançon presents a glider inspired by a 1925 Italian glider. A model that's easy to build and offers reliable performance, perfect for those approaching this fascinating world for the first time.

I've always liked small gliders because they require significantly less effort than larger models, and they pose fewer problems for transportation and storage. On the other hand, it's clear that the flight is less majestic than that of a large model, but every now and then it's nice to have a change. The idea of building the GP1 came to me after reading its history in Vincenzo Pedrielli's book 'Vintage Italian Gliders.'

This glider, which had a wingspan of 17.80 m, was designed by engineer Abate on behalf of the Pavesi University Students Association (ASUP), who wanted to dedicate it to Giovanni Pirelli, a friend who died in a flying accident. The GP1, piloted by Ettore Cattaneo, set the world distance record in 1926 with a launch from the Campo dei Fiori in Varese. The wing consisted of three pieces, with the central section without dihedral, while the tips were tapered and raised. The wing structure was made of wood, while the covering was made of fabric, including the ailerons.

As was customary at the time, no aerodynamic braking system was installed. The fuselage structure consisted of frames connected by four stringers. The covering was made of plywood. A shock-absorbing skid was installed in the front-lower part of the fuselage. The empennage, with rounded tips, was of the classic type, covered in fabric. The 1:10 scale model has a wingspan of 178 cm, a chord of 16 cm at the root and 11.5 cm at the tip. With an estimated weight of approximately 400 g and a surface area of 25 dm2, this results in a wing loading of only 16 g/dm2.

The profile is the classic Clark Y, easy to build and particularly suited to the characteristics of the model. To simplify the construction, even if the overall appearance suffers somewhat, I created a two-part wing with simple dihedral, while the original had a three-part wing: a flat central wing and two lateral wings with a slight dihedral. For those who wish, it will be very easy to make a 'scale' modification, but my goal in this case was not to make a reproduction, but just a recreational model that closely resembles the original.

Empennage: Let's start with the simplest thing: the tail, precisely. The main spars of the stabilizer joint are made of 2x8 balsa, glued sideways to form a T-profile. Between the fixed and the moving part, a 2 mm strip is temporarily glued with a few dots of glue to the contact. This acts as a spacer and will be removed after sanding the stabilizer.

The trailing edges of gliders and airplanes of that era were often made of steel cable, which, under the tension of the canvas, curved significantly with the classic 'batwing' effect. To reproduce this effect, I didn't use shaped balsa, but I did as was used at the time, using Kevlar wire instead of steel, which, at this scale, would have been too stiff and heavy. The Kevlar is inserted into slots and secured with cyano, taking care to leave a little slack between each rib because the covering would not be able to stretch it sufficiently. The wingtips are made of 2 mm wicker (or bamboo)..."

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