P.Z.L. P.24 from the Front
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The P.Z.L. P.1 of 1929 was the first Polish designed fighter aircraft, and was the first in a line of fighters that would still be in front line service a decade later, at the outbreak of the Second World War.
The aircraft was designed by Zygmunt Pulawski, a graduate of the Warsaw Technical University, whose previous aircraft design experience was limited to the construction of a S.L.3 glider and a design study for a two-seat army support biplane. Despite his limited experience, Pulawski came up with an advanced design.
Pulawski decided to produce a high wing monoplane. These came in two types – the shoulder mounted type, where the wing blocked the view down, or the parasol type, where the view down was clear, but the wing restricted the view up, and the struts needed to support the central section of the wing added to drag. Pulawski decided to adopt a gull wing, with the main part of the wing above the level of the fuselage, but with the inner sections angled down to connect to the sides of the fuselage. This section was also reduced in chord and thickness. This reduced drag, and greatly improved the pilot’s forward view. This ‘Pulawski Wing’ was used on the entire family of fighters that developed from the P.1, so was still in front line use at the start of the Second World War.
The aircraft was of all metal construction. The wings used a Polish designed Bartel 37/IIa aerofoil section, with slotted ailerons that also acted as landing flaps. The landing gear introduced more innovations, with oleo-pneumatic shock absorbers mounted inside the fuselage connected to the wheel strut on the opposite side. The result was a clean looking undercarriage, known as the ‘scissor-type’. It was powered by a 12-cylunder Hispano-Suiza 12b Vee-type engine, which produced 630hp at take-off. The fuselage was built around a rectangular central section, with domed structures on the top and bottom. It was armed with two 7.7mm Vickers machine guns, carried in the fuselage. A total of 87.9 imperial gallons of fuel could be carried in two tanks, one in each wing.
Work on two prototypes and a structural test airframe began in January 1929.
The first prototype, P.1/I, with a 600hp Hispano-Suiza engine, was ready for its first flight late in August 1929, but as it gathered speed the Electron metal D leading edge of the wings began to deform, and the flight had to be aborted. After the leading edge was strengthened the aircraft made its full maiden flight on 25 September 1929. There were some problems with stability, but in general the first prototype performed well.
The second prototype, P.1/II, was built with an improved shape to the nose, a new fin and rudder and a repositioned radiator bath. It made its maiden flight in March 1930. In June 1930 this aircraft was sent to the International Fighter Contest in Bucharest, where it came first in eight of the fifteen categories, but because of the way the final positions were worked out ended up coming fourth.
The Polish Air Arm was interested in the overall design but wanted to use radial engines, so work moved onto to P.Z.L. P.6 and P.Z.L. P.7, two very similar projects, but with low altitude and high altitude engines. Some work did go into an improved version of the P.1 in the winter of 1929-30. A scale model of the new design was produced, and it was given the provisional designation P.Z.L. 2 (later reused on a different design), but this project was abandoned. Pulawski didn’t give up on the inline version, producing the more advanced P.Z.L. P.8, but like the P.1 that version never entered production.
P.1/ II
Engine: Hispano-Suiza 12Lb 12 cylinder upright V liquid cooled engine
Power: 600hp
Crew: 1
Span: 35ft 7.5in
Length: 22ft 11in
Height: 9ft 1.5in
Empty Weight: 2,465lb
Loaded Weight: 3,482lb
Maximum Speed: 187.6mph at sea level; 182mph at 6,561ft; 176.4mph at 16,404ft
Climb rate: 2 min 40 sec to 6,561ft; 9 min to 5,000ft
Ceiling: 28,214ft (absolute ceiling)
Range: 373 miles
Guns: Two 7.7mm Vickers machine guns.