C.Jerzy Polish Aircraft 1893-1939 (Putnam)
From boyhood, Ryszard Bartel was absorbed with the problems of flight. Passionately studying all the available literature on the subject, he constructed his first flying model in 1909. This was an ornithopter-type machine powered by a clock mechanism, with wings like Venetian blinds which shut during the downward beat. Later he built larger wings, which were constructed on the same principle and had a span of 1.5 m (4 ft 11 1/2 in). They were hinged to a light frame carried on the shoulders and strapped to the body. Bartel tried a few jumps with this device.
During the later period he evolved a number of model aircraft, some of which were powered by ingenious compressed-air engines of his own design. The problems of longitudinal and lateral stability attracted his particular attention and by conducting tests with his models and observing their behavior he gained a considerable knowledge of the principles of mechanical flight.
In 1911, inspired by descriptions in aviation publications of Tanski's works and experiments, Bartel designed a tail-first man-carrying glider, which resembled in general layout some of Tanski's projects. The machine, which was to be operated in the same manner as the Lotnia (its pilot had to hold it in his hands and run against the wind), proved too heavy for the then only 14-year-old boy to handle. Later in 1911 Bartel extensively revised the design. The new glider, while retaining the wings and tail unit of its predecessor, was of conventional configuration and embodied a completely new, very light and simple fuselage frame, built up of a minimum amount of wood and well trussed by steel wires. However, this frame was too fragile and broke during the first attempt at flight. The young designer then devised an improved reinforced frame, and the glider in this form was first tested flying as a kite and carrying a small boy 1-2 ft above the ground.
Bartel subsequently made a number of short jumps with the glider from the hill slopes of the Renard quarry at Sielec near Sosnowiec in Silesia. These usually ended with one wingtip coming in contact with the ground, but without damage to the craft. The very short duration of each jump did not allow the pilot to make use of the controls with which the aircraft was provided. The experiments were interrupted when the Bartel family moved from Silesia to central Poland. In spite of its great simplicity, the Bartel glider was an ingenious and purposeful design. During its development and improvement the young constructor was advised by his older friend Aleksander Stephan, then a student at the Lwow Technical University.
The Bartel glider was a very simple open-frame monoplane of wooden construction. The whole airframe was glued and nailed together and all fixtures were made of thick wire. The single-surfaced wing, with an area of 14 sq m (150.7 sq ft) and chord of 2 m (6 ft 7 in), was covered with fabric impregnated with starch, the fabric being nailed to the framework. The fuselage consisted of two longerons trussed with steel wires and carried a movable tail unit, which comprised a pivoting one-piece horizontal surface with a rudder on top. The seat was a canvas cushion filled with straw, and hung under the wing on ropes. The control stick above the pilot's seat provided means of control, devised to follow the automatic reflexes of the pilot. The fore and aft movements of the stick controlled longitudinal stability in the manner opposite to the conventional system (forward for nose up and aft for nose down attitude), and sideways movements, which operated the rudder, combined with the natural movements of the pilot's body, controlled the lateral and directional stability. According to the designer's data, the span of the glider was 7 m (22 ft 11 3/4 in) and the length 4.75 m (15 ft 7 in).