PZL P.24 A-G

Although built in fewer numbers than the  PZL P.11, the PZL P.24 was for a period   during the 1930's the fastest and most heavily armed single-seat fighter in the world. Having acquired early notoriety at the Paris Salon with their innovative wing design, the P.24 represented the ultimate development of the family of fighter planes designed by Zygmunt Pulawski and saw service in the air forces of four countries: Bulgaria, Greece, Romania and Turkey.

When PZL (Panstwowe Zaklady Lotnicze, or National Aircraft Works) opened for production near Warsaw's Mokotow airfield in 1928, twenty-seven year old Zygmunt Pulawski was hired as the main designer. In 1925 he had graduated with honors from the Department of Mechanics at Warsaw Polytechnic and was awarded an apprenticeship at the Breguet airplane factory in France. Having graduated in 1927 from Air Officer Cadet Reserve School, where he earned his pilot's license, he was hired by the Central Aircraft Machine Shops in Warsaw, which later became PZL.
Pulawski's talent finally had a platform at PZL and his first project was to design an all– metal fighter plane. At the time, most planes were either wooden or mixed structure, with welded fuselages and wooden wings. Duralumin was used on very few planes.

Pulawski's concept fighter
Pulawski's original fighter design, the P.1, brought him and PZL recognition for its innovative gull-shaped wing (thin and canted or 'gulled' upwards at the fuselage, gradually becoming wider and leveling out at the wingtips with underwing struts) which ensured excellent forward visibility from the cockpit, great strength and light weight. They were later called "Pulawski wings" or "Polish wings."
Another design innovation was the "scissors" undercarriage. It allowed the shock absorbers to be hidden in the fuselage, thus reducing drag. The shocks were compressed by levers and rods in a system that is used to this day in airplanes around the world, including the Polish PZL-106 "Kruk" used in agriculture.

P24  z1

Pulawski's imitators around the world
There were many imitators of the "Pulawski wing" around the world with the most similar being the French-made fighters Loire 43 (1932), Loire 45 (1933) and Loire 46 (1934), the Czechoslovakian Aero A-102 prototype (1933) and the German Henschel Hs 121 (1934), all based on the Pulawski design. The "Pulawski wing" was also used on the following airplanes: the Yugoslavian Ikarus IK-1 (1935) and Ikarus IK-2 (1936), the French Mureaux 170 (1933) and Mureaux 180 (1934), Gourdou Lesseure GL-482 (1933) and the Arsenal-Delanne 10 (1940). In 1930 the American observation plane Douglas O-32 made use of the "Pulawski wing" with cable supports instead of the usual struts. The German Dornier Do-C1 used the "Pulawski wing" mounted on small posts away from the fuselage. In 1934 two planes, the British Armstrong Whitworth AW 32 and the Hungarian Weiss WM-18, were designed with the "Pulawski wing," but never made it into production. The only twin engine planes to be outfitted with the "Pulawski Wing" were twelve American Douglas O-37/B7's (1931).
Pulawski's gull wing design was also adapted for the following biplanes: Soviet fighter planes including the Polikarpov I-15 (1933, 450 built), I-153 Czajka (1938, 3,400 built) and the Nikitin-Szewczenko IS-2 (1941), the Italian fighter plane Romeo 41 (1933, 180 built) and seaplanes Romeo 43 (1935, 100 built) and Romeo 44 (1938, 25 built), the French seaplanes Romano R-90 (1935) and R-92 (1936), the Czechoslovakian Avia B-422 (1938), the British Westland F7/30 (1931), the American-built Curtiss F9c-3 Sparrowhawk (1932), the Canadian Gregor FDB-1 (1935) and the American-built Lamson L-101 Air Tractor ag-plane.
Pulawski's gull wing concept was also used on multi-engine seaplanes, although its purpose was different from that in the fighter; the gull wing design allowed the engines to be mounted further away from the waterline as seen on the British Short S-18 (1933), the German Dornier Do-26 (1938, 6 built), the American Martin Mariner (1939, 1,325 built) as well as the Soviet Berijew Be-6 (1949) and Be-12 Czajka (1963, 132 built).

P24  z2

A few concepts inverted Pulawski's idea with a low-wing design strutted upwards with the wings narrowing at the fuselage: the German Henschel Hs 125 (1935), the Soviet CKB-4 (TSz) and the Polish Szpak-2, -3 and -4 (1945-48, 13 built).
Gull wings were often used in the 1930's on stunt gliders to raise the frail wingtips thus avoiding damage during landings. Gull wings also increased the stability of gliders during rolls. It was first used on the German glider Fafnir in 1930. Some examples of Polish gull wing gliders are: CW-5 bis, SG-3 bis/36, SG-7, Orlik, Mewa, PWS-101, PWS-102 Rekin, PWS-103, WWS-2 Delfin, B38 and the Jastrzab.