(PZL stands for Panstwowe Zaklady Lotnicze, or State Aircraft Factory, which still exists.)
So rapid was combat aircraft development in the previous few years that, although Lieutenant Gnys’s P-IIC may have been built less than four years before, it was at least a generation behind Germany’s Messerschmitt Bf 109E and Britain’s Spitfire I, which were conceived in 1935 and had been continuously developed ever since—the Messerschmitt spurred by its operational testing during the Spanish Civil War. Nevertheless, the 175 P-IIC fighters of the Lotnictwo Wojskowe claimed the vast majority of the fighter force’s 126 confirmed victories during the sixteen-day invasion. This figure is thought to be only half the number of Luftwaffe aircraft the PZLS actually shot down.2
The opportunity for a leap forward in fighter design occurred, as it often does, because of the recent availability of advanced engines. Poland’s Skoda works had begun licence-building the Bristol Aeroplane Company’s Mercury radial engine in 1930.
Radials, so named because their cylinders radiate out from a central crankcase, are air-cooled engines. Their advantages include dispensing with the weight of liquid-cooling plumbing and the coolant itself, thus increasing payload. As fighter powerplants, radials are less susceptible to battle damage; a stray bullet through a radiator could disable a liquid-cooled fighter’s engine in seconds. The radial’s drawback was its need to be open to the air, causing drag. At that time, suitable methods of smoothing the airflow around a radial’s cylinders were only just being developed, so the liquid-cooled engine, which allows a nearly pointed nose profile, still held the aerodynamic advantage.
The Mercury was a de-stroked development of Bristol’s well-proven Pegasus radial; its shorter cylinders formed a smaller-diameter, if still blunt, nose.
On the airframe side, PZL, an expansion of the previous Central Aviation Workshops, was founded with a specific purpose in mind: to undertake the next step forward in aircrait structures by taking advantage of the lightness and strength of all-metal construction.
The series forerunner, the P-I, was designed under the leadership of Dipl.-Ing. Zygmunt Pulawski, who appears to have been a talented designer. He had produced a glider while at Warsaw Technical University, had won an apprenticeship at France’s Breguet plant by designing the third-place finisher in Poland’s 1924 contest for a combat aircraft design, and had learned to fly when the PZL organization was founded by Poland’s government the first day of 1928. But Pulawski, not yet thirty, died in an airplane crash March 31, 1931.3
With Pulawski’s death, the PZL fighter’s development was taken over at an early stage by his assistant, a big, cultured and worldly engineer named Wsiewolod J. Jakimiuk (pronounced Jaki-mook). Jaki, as he became known much later at Downsview, was a natural team leader. Physically imposing at over six feet and 200 pounds, with fine engineering credentials of his own, multilingual and an opera buff, Jakimiuk had easy social graces and was married to a talented French-English wife, Mary.
In 1931 the P-I was the most advanced fighter plane in a world that would continue building its possible rivals out of wood, wire and linen for years to come. The first prototype had a neatly-streamlined, water-cooled Hispano-Suiza V-12 engine, and its high-set gull wing met the upper fuselage at the aerodynamically-optimum 90-degree angle before extending horizontally outward to its gracefully rounded tips. The engines in-line cylinder heads formed the same angle as that of the wing roots behind them, producing a forward view for the pilot over this shallow v wing centre-section and engine that was outstanding. The P-I won a fighter competition in Bucharest in 1931 over such contemporaries as the British Bristol Bulldog and the French Dewoitine D.17, and was extensively showcased for a year, appearing, among other places, at the 1932 National Air Races at Cleveland.
The P-I’s wing, covered with finely corrugated duralumin alloy grooved front-to-back, was imitated by at least seven European aircraft types.4 Pulawski took the basic P-I design through a number of beautifully-streamlined V-12-powered developments until, at the Polish military’s insistence, the P-6 was fitted with the more readily available licence-built Bristol radial near the time of his death.5 The 500-hp Jupiter radial (which also powered the Bulldog) was an important advance in powerplant technology in its day, but it altered some of the more desirable features of Pulawski’s original conception, such as the uninterrupted vision forward.
The Beaver would go more successfully through a similar design evolution from a more-streamlined but less-powerful in-line powerplant installation to a more-easily-available air-cooled radial, making it, like the PZL, more of a blunt object—louder, tougher, brawnier, more muscular. Moreover, the absence of liquid coolant was an obvious advantage in the frigid regions where the Beaver was intended to fly.
Renowned for its all-metal construction techniques by the late 1930s, the PZL factory hosted delegations from Romania and Britain, who spent long periods there learning their trade secrets. The Romanians, having licence-built the P-IIC for their own air force, spent six months at the Okesie-Paluch plant near Warsaw studying Jakimiuk’s design philosophy, borrowing dozens of his engineers, and ending up simply copying the characteristic PZL tail for the IAR-80 series fighters that became operational during the war.
In 1937, engineers from the de Havilland Aircraft Co. of Hatfield, England, arrived for the same purpose and got to know the charming “engineer’s engineer,” as de Havilland Canada employees of the time remember him.6 The de Havilland company, the oldest and most prolific aircraft manufacturer in England, had built some of the fastest airplanes in the world out of wood. But for the twelve-to-seven-teen-passenger airliner de Havilland had in mind for the late 1930s, all-metal was the way to go.
The DH.95 Flamingo was de Havilland’s first all-metal design when it first flew December 28, 1938, in the hands of Geoffrey de Havilland Jr., the son of the company’s founder, and George Gibbins. This was easily the most modern airliner built up to then in Britain. A Flamingo was used by Winston Churchill and his advisors for vital trips to France before Dunkirk. Had the Germans invaded Britain in 1940, the royal family would have been evacuated from London in one of the thirteen Flamingos built. An engineering-physics student from the University of Toronto, Dick Hiscocks, was doing his internship at the Hatfield plant.
Jakimiuk’s P-II model appeared later in 1931. While the first prototype flew in August of that year with a Jupiter engine, subsequent pre-production units had the more powerful Mercury IV radials that developed 800 hp for takeoff. Early P-IIS were introduced into service in 1935, the year the Bf 109 and Spitfire prototypes appeared.
The P-IIC, which reached Polish fighter units later in 1935, featured such small refinements as an exhaust-collecting engine cowling ring that minimized turbulent airflow around the bulky radial. Some P-IIS even carried four machine guns, with the addition of one in each wing panel. The Romanians built seventy P-IIS at their Industria Aeronautic Romana (IAR) plant during 1936—37.
A development of the P-II, the p-24 was an even greater export success for PZL and Jakimiuk. The P-24 had heavier armament, including two 20-mm Oerlikon cannon, and a fully-enclosed cockpit. Greece bought 36, Turkey 60, Bulgaria had received 36 of a 46-piane order at the outbreak of war, and old customer Romania had 50, 44 of them built by IAR.7
But P-24s in foreign hands were useless to the Poles in September 1939. With non-adjustable laminated wood propellers that compromised both takeoff and high-speed performance, drag-producing fixed landing gear, and open cockpits, the P-IIS Polish Military Aviation took to war were pressed to exceed 200 mph at anything under 8,000 feet, where most dogfights took place.
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