J.Zynk Polish Aircraft 1893-1939 (Putnam)

Latka Monoplane. In 1909 Tanski had completed a study for a single-seat monoplane named the Lattka (Libellula), which incorporated an extraordinary feature: the angle of incidence of its entire wing could be varied in flight. A very large drawing of this project was prominently displayed at the 'Exhibition of Czeslaw Tanski's model flying machines' in December 1909, which was intended to raise some money towards the cost of building the aeroplane (estimated at 3,500 roubles or some ?370), and construction of its first components began before the year was over.
   Due to the cramped conditions in his Mazowiecka Street workshop and various other difficulties, work on the Latka, for which Tanski managed to obtain a 25 hp Anzani three-cylinder air-cooled semi-radial engine, progressed at a very slow rate, and as time went by the design was modified and improved. Counting on the possibility of getting a 50 hp Gnome rotary engine, the designer strengthened the structure. Frequent failures of contemporary undercarriages led him to pay particular attention to the development of a strong and safe landing gear, which was continuously revised and eventually materialized as a conventional and very heavy structure. Its final configuration appeared to be an unfortunate choice, inferior to the previous highly original, flexible and lighter design.
   By the early autumn of 1910 Tanski completed the airscrew, landing gear and a large part of the fuselage, but limited space prevented him from constructing the wings. He had to find larger premises and considered moving either to the Aviata factory in Mokotow or outside Warsaw. On 8 October, 1910, he transported all the parts of his machine from the Mazowiecka Street workshop to the Aviata hangar No. 2 and in the middle of that month began constructing the wings. At the end of 1910 he transferred his workshop to the Aviata hangar No. 7, which he liked better. During the winter, work on the Latka almost came to a halt, and the aircraft, fitted with the 25 hp Anzani engine driving the Tanski two-blade airscrew, was eventually finished only in the autumn of 1911.
   Taxi-ing trials and take-off attempts were made at Mokotow aerodrome mainly by Stanislaw Supniewski and on one or two occasions by one of the earliest and best-known Polish pilots, Michal Scipio del Campo. The latter, referring to the 'only interesting feature' of the design, the variable angle of incidence of the wing, wrote: The engineering solution of this idea consisted of a system of pulleys connected by an ordinary hemp rope. One could imagine how this would function in the air. By the grace of providence this contraption never left the ground, otherwise a disaster would have been unavoidable. Looking back at this, I had to be very foolhardy to attempt to fly it.'
   After the first unsuccessful take-off attempts the Latka was provided, in 1912, with a triangular fin and rudder, but this did not persuade it to leave the ground, and the aircraft proved to be a total failure.

Construction: The Latka was a single-seat wire-braced monoplane of wooden construction. The elliptical wings, attached to the fuselage top longerons by means of short, heavy main spars around which they pivoted to vary the angle of incidence, were built up of three light spars and curved lattice ribs. The high aspect ratio wing panels, of the double-surfaced fabric-covered variety, were braced by steel wires to the inverted V cabane on top of the fuselage and below to undercarriage frame members. Wing warping was used to maintain lateral stability. The fuselage consisted of a rectangular wooden forward section, which carried the engine, undercarriage frame and pilot's seat, and a triangular rear section constructed of bamboo sticks. The tail unit initially consisted of a one-piece movable horizontal surface only, but later the fin and rudder were added. Each unit of the divided landing gear consisted of a pair of wheels attached to a skid, and twin bamboo tailskids under the tail. Dimensions, estimated from Tanski's own drawings, included an overall span of 14.4 m (47 ft 3 1/4 in) and overall length of 9.4 m (30 ft 10 1/4 in). Weights are not known.