J.Zynk Polish Aircraft 1893-1939 (Putnam)
Edmund Libanski evolved a study for his second aircraft in the autumn of 1910. The machine, a two-seater believed to be initially designated the Mono-biplan II, was generally much more advanced and incorporated some startling features. Its main wing was swept back to 'increase speed and improve stability', and the machine was to operate either with or without its detachable short-span wing, which was carried on struts above the main wing and, in contrast to the Mono-biplan I, was provided with a movable flap to lower the speed of descent during landing. Because of its sweptback wing the aircraft was eventually named the Jaskolka (Swallow).
In December 1910, Libanski hired a disused hall from the Lwow town council and began construction of the Jaskolka with the help of Witold Rumbowicz. The airframe was completed in the late spring and slightly modified in the middle of 1911, and. presumably to ensure good airfield facilities and an experienced pilot, the designer offered the machine for tests to the Austrian military authorities. The Jaskolka was transported to Wiener-Neustadt airfield and assembled there in one of the military hangars under Libanski's supervision. In August 1911, the Jaskolka in its true monoplane form made the first successful, sustained, and controlled flights at Wiener-Neustadt, thus becoming the second machine (after the Glowihski monoplane) built in Poland to do so.
The fate of the aircraft is obscure and it has to be presumed that the supplementary top wing was never tested in the air. Although the Libanski flap gear was a very primitive device and was apparently never used, it was nevertheless a brilliant example of ingenuity and technical foresight on the part of its inventor and served as the inspiration for several Austrian designers. An essentially identical device was described by von Jirotka in the Osterreichische Flug-Zeitschrift of August 1911, in connection with proposals for his own aircraft (which generally resembled Libanski's Jaskolka), and a month later the same magazine printed photographs of the Jaskolka and recognized that the credit for the 'braking' flap should go to Edmund Libanski, who evolved it almost a year earlier. The efforts of other Austrian designers (including Karl Bombard, whose machine, also called the Mono-biplan, was test-flown at Wiener-Neustadt in January 1912, by Adolf Warchalowski) were also inspired by the Libanski-system wing concept, this being the first instance of an aircraft design evolved in Poland exercising an impact upon international aviation development.
It is obvious that the well-known Jaskolka formed a most formidable challenge to Zbieranski's claim to the title of the first and only successful Polish aircraft designer of that era. Zbieranski published the following statement on p. 101 of his book O narodzinach lotnictwa poiskiego (see Zbieranski and Cywinski biplane): 'The photograph depicting this aircraft, allegedly made by Ing Libanski and Rumbowicz in Wiener-Neustadt, was shown in Z. Dekler's "Aero-Office" in 1911 as the product of an Austrian T. Flieger from Vienna, anyway who with whom built this aeroplane is of secondary importance; the important thing is that the aircraft never found itself on Polish territory and cannot be included in Polish aviation. It had nothing to do with the birth of aviation in Poland.'
In the interest of historical truth it must be made clear that: 1) Tomasz Flegier (not Flieger) was always referred to as a Polish pilot, and as such gave a number of flight demonstrations in various foreign towns, including Riga (as evident from Swiat, 1911, No. 14, p. 13 and other press reports of the period); 2) there is not a shred of evidence to connect Tomasz Flegier with the design or building of the Jaskolka in any way (at that time he was in Russia); 3) not only Polish but also all contemporary Austrian documents and publications acknowledge without reservation that the sole designer and inventor of the Jaskolka and all its features was Edmund Libanski (Rumbowicz only helped him to build the machine in Lwow); 4) as already stated (on the evidence of Polish press reports of the period, e.g. Swiat, 1911, No. 35, p. 14) the Jaskolka was built in Lwow and taken to Wiener-Neustadt only for tests. In view of the above facts, Zbierariski's statement that the machine 'had nothing to do with the birth of aviation in Poland' is astonishing.
When Libanski went to Wiener-Neustadt with his Jaskolka, Witold Rumbowicz and Tomasz Flegier evolved jointly a design for their own monoplane project, which was derived from the Jaskolka. Construction of this machine, referred to as the Rumbowicz-Flegier system monoplane, was undertaken by the Warsaw 'Aero-Office' (the ownership of which passed at that time from Dekler to Stepowski and Rumbowicz) in the autumn of 1911. The airframe, built by Stepowski and Rumbowicz, was almost finished in 1912, but nothing is known about its final completion or subsequent fate and no technical details are available.
Construction: The Jaskolka was a two-seat braced sesqui-/monoplane, built of wood, except for the landing gear. The main wing, featuring a very pronounced sweepback, was a divided two-spar double-surfaced structure and was provided with ailerons. The wing panels, set at a coarse dihedral angle, were attached to the upper fuselage framework and braced to the cabane on top of the fuselage, and below to the fuselage and landing gear framework. The detachable supplementary short-span wing, equipped with the movable "braking" flap, was carried high above the main wing on two pairs of struts. The main fuselage frame, trussed by wires, was of rectangular section and was partly covered with fabric. The pilot's cockpit, equipped with a steering wheel on a control column which effected all controls, was situated immediately behind the cabane. Provision for another seat was made behind the pilot. The tail unit, a conventional monoplane structure covered with fabric, consisted of a triangular fin and rudder, tailplane and one-piece elevator. The tailplane, carried on struts below the rear end of the fuselage, was braced by struts and wires. The landing-gear framework, built up of metal tubes, was attached to the first fuselage frame and supported by a system of struts. The landing gear consisted of two front wheels provided with spring shock-absorbers and a tailskid. The Jaskolka was powered by a 28 hp Delfose three-cylinder rotary engine, mounted in front of a two-blade tractor airscrew. The span of the aircraft was 10.6 m (34 ft 9 1/2 in). The empty weight was 240 kg (529 lb) and the maximum loaded weight, as a two-seater, 450 kg (992 lb).