PZL_P.1 Knowpia

PZL P.1
	PZL P.1, second prototype
Role	Fighter
Manufacturer	PZL
First flight	August 1929
Status	Prototype
Primary user	Polish Air Force
Number built	2

The PZL P.1 was a Polish fighter, designed by the engineer Zygmunt Puławski, manufactured by the PZL state-owned factory. It remained a prototype, but it was the first of the Polish PZL gull wing fighter series, leading to the PZL P.7, PZL P.11 and PZL P.24.

Design and development edit

Among the first tasks of newly created in 1928 PZL aircraft works was to design a modern fighter for the Polish Air Force. As a result, a construction team led by the talented young designer Zygmunt Puławski designed an all-metal, metal-covered monoplane fighter, designated PZL P.1. Puławski included a high gull wing, to give a pilot an optimal view, without an upper wing before his eyes, like in classic parasol monoplanes and biplanes of that time. The wing, supported with struts, could be thin in its root part, at joint with a fuselage. Other innovations included a scissors-like fixed undercarriage, with shock absorbers hidden in the fuselage. The P.1 was powered with a 630 hp (470 kW) Hispano-Suiza inline engine.

The first prototype was flown in August 1929 by Bolesław Orliński. In the first flight, the wing leading edge distorted, but Orliński saved the aircraft and possibly the program. In late 1929, after static trials, the prototype was modified and strengthened. In March 1930, the second prototype was flown (P.1/II). It introduced, among other changes, a revised rudder shape, similar to those used on later fighters.

The second prototype took part in a fighter contest in Bucharest in June 1930, where it placed 4th out of 7 competitors, but it won in 8 of 15 trials.

The P.1 remained a prototype, because it was decided that a fighter for the Polish Air Force would be powered with a radial engine produced in Poland. As a result, the next fighter designs were produced with radial engines, but were still based upon the P.1, starting with the PZL P.6. This decision has since been criticized by some modern authors, as single row radial engines produce more drag, without advantage of more power, and reduced visibility from the cockpit.^[1] It was planned in 1929-1930 to build an improved P.1, with the designation PZL P.2, but this was abandoned after building the fuselage. Puławski himself hoped for a second chance to build fighters powered with inline engines, and developed the PZL P.8 with an inline in 1931.

Technical description edit

First prototype after modification

The PZL P.1 was an all-metal braced high-wing monoplane, duralumin-covered. The fuselage was made of a duralumin frame, rectangular in cross-section. Two-spar wing of trapezoid shape, thinner by the fuselage, covered with a rimmed Wibault type duralumin sheet, supported with two struts on either side. Pilot's cockpit was open, with a windshield. Two fuel tanks in wings (400 L). A fixed undercarriage with a rear skid. Inline engine in front, with a water radiator under the fuselage, two-blade propeller.

Operators edit

Poland

Polish Air Force

Specifications (P.1/II) edit

Data from Jane's all the World's Aircraft 1931,^[2] Polish aircraft, 1893-1939^[3]

General characteristics

Crew: 1
Length: 6.98 m (22 ft 11 in)
Wingspan: 10.85 m (35 ft 7 in)
Height: 3.05 m (10 ft 0 in) in the rigging position
Wing area: 19.5 m² (210 sq ft)
Aspect ratio: 5.97
Airfoil: Bartel 37/IIa (modified)
Empty weight: 1,118 kg (2,465 lb)
Gross weight: 1,580 kg (3,483 lb)
Fuel capacity: 400 L (110 US gal; 88 imp gal) in two wing tanks with a small gravity collector tank in the fuselage
Powerplant: × Hispano-Suiza 12Lb V-12 water-cooled piston engine., 470 kW (630 hp)
Propellers: 2-bladed fixed-pitch propeller

Performance

Maximum speed: 302 km/h (188 mph, 163 kn) at sea level

293 km/h (182 mph; 158 kn) at 2,000 m (6,600 ft)

284 km/h (176 mph; 153 kn) at 5,000 m (16,000 ft)

Cruise speed: 250 km/h (160 mph, 130 kn)
Stall speed: 102 km/h (63 mph, 55 kn)
Range: 600 km (370 mi, 320 nmi)
Endurance: 2 hours at cruising speed.
Service ceiling: 8,600 m (28,200 ft) Absolute
g limits: Tested to 13.5g ultimate load
Time to altitude: 2,000 m (6,600 ft) in 2 minutes 40 seconds.

5,000 m (16,000 ft) in 8 minutes

Wing loading: 81 kg/m² (17 lb/sq ft)
Power/mass: 0.633 kW/kg (0.385 hp/lb)

Armament

Guns: 2 x 7.7 mm (0.303 in) Vickers E machine guns in a fuselage, with 800 rpg (planned).

References edit

^ Krzysztof Cieślak, Wojciech Gawrych, Andrzej Glass: Samoloty myśliwskie września 1939, NOT-Sigma, Warsaw 1987, ISBN 83-85001-11-5 (in Polish)
^ Grey, C.G., ed. (1931). Jane's all the World's Aircraft 1931. London: Sampson Low, Marston & company, ltd. pp. 222c-223–c.
^ Cynk, Jerzy B. (1971). Polish aircraft, 1893-1939. London: Putnam. pp. 123-128. ISBN 0-370-00085-4.