PZL.50 Jastrząb
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| PZL.50 Jastrząb | |
|---|---|
| Type | Fighter aircraft |
| National origin | Poland |
| Manufacturer | Państwowe Zakłady Lotnicze |
| Maiden flight | February 1939 |
| Status | prototype |
| Primary user | Polish Air Force |
| Produced | 1939 |
| Number built | 1 (+2 incomplete) |
PZL.50 Jastrząb (Hawk) was a Polish pre-war fighter aircraft designed by Wsiewołod Jakimiuk of the PZL works. A single-seat low-wing monoplane was to serve as a multi-purpose fighter and escort and replace all fighters used previously by the Polish Air Force. Designed after 1936, its prototype was first flown in February of 1939. Further two prototypes were almost ready by the time of the Invasion of Poland, but the plane did not manage to enter mass production before the war.
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[edit] Design and development
In early 1930s the Polish Air Force was equipped with modern all-metal high-wing monoplanes PZL P.11, of a family designed by Zygmunt Puławski. However, by the end of decade they became obsolete, as new fighter and bomber aircraft with higher performance started to appear. In the mid-1930s, the Polish Air Force Command led by Gen. Ludomił Rayski expected, that a basic Polish general purpose fighter and light bomber would be a twin-engine heavy fighter-bomber PZL.38 Wilk, supplemented by light, cheap low-wing monoplane PZL.39/LWS-4[1]. There were no works carried on other fighters, apart from export variants of PZL P.24 of Puławski's family. The estimated performance of PZL.39 was however too low (maximum speed 400 km/h), while attractive at first glance design PZL.38 had troubles with finding proper engines and both programs had to be canceled[2]. Future wartime experience showed, that heavy fighters cannot substitute for fast single-engine interceptors, anyway. It became evident, that the Air Force needed a modern interceptor aircraft to defend the country, and at last, in October 1936, the Armament Committee (KSUS) submitted a demand for such plane[1]. Therefore, in late 1936 Rayski ordered Wsiewołod Jakimiuk of PZL (National Aviation Works) in Warsaw, a lead designer of the P.11c, to abandon completion of the passenger airliner PZL.44 Wicher design and start work upon a modern single-engine fighter with a retractable landing gear and a speed of some 500 km/h. At the same time, Rayski picked up the British 840 hp Bristol Mercury VIII radial engine, easy to build in PZL, which had already manufactured Mercury V engines. This choice however restricted performance of the future fighter, and, according to historians, the whole program started at least two years too late[3].
The works upon the plane, designated PZL.50 (or PZL P.50) and named Jastrząb (Hawk), started in late 1936[1]. The design was accepted by the Air Force Command in 1937 and two prototypes were ordered. Also, in June 1938, 300 engines Mercury VIII were ordered in the PZL, the first to be delivered in June 1939. The engine for the prototype was imported from Great Britain and fitted in September 1938. The prototype was almost ready by October, but its completion was delayed by lack of a retractable landing gear, delivered by the British Dowty firm with delay (the Polish aviation authorities missed the chance of starting flying tests with some temporary fixed landing gear, while the Polish industry have not produced suitable retractable gears yet)[1].
Finally, the first prototype PZL.50/I was completed and flown in late February 1939 (pilot Jerzy Widawski). Despite being secret, on 27 February it was presented on the ground to the Italian ministry Galeazzo Ciano. Tests were carried mainly by Bolesław Orliński and several other pilots. It was revealed, that it had good handling and maneuverability, but it developed speed only 420-430 km/h, without radio and machine guns in addition. Pilots complained about too low power output, caused by too weak engine (in addition, the engine had problems with delivering full power due to an unsuitable carburetor intake - after fixing it, the plane once developed 442 km/h).[1] Some estimate, that a production plane would be able to develop 470 km/h.[2]
It was first planned to order 500 P.50s, but in April 1939, new Air Force Commander gen. Kalkus and Air Defence Inspector Gen. Józef Zając estimated, that PZL.50 did not fulfill hopes and decided to develop it further, building an improved pattern aircraft and a short series of 25-30 aircraft only, designated P.50A.[1][4] Production aircraft were to have wing area increased from 15.8 m² to 19 m²[2]. Total planned order was decreased to 200 and Poland started to look for fighters abroad, ordering 160 Morane-Saulnier MS 406 fighters from France[4] and 10 Hawker Hurricanes. As an interim measure, 100 PZL P.11g Kobuz fighters were ordered, merging P.11c airframe with Mercury VIII engines.
The second prototype PZL.50/II was to be fitted with stronger 1200-1400 hp engine, but it had not been completed with engine eventually. Only in 1939 it was decided to test it with 1100 hp Gnome-Rhone 14N21 for an export variant P.50B (estimated maximum speed 560 km/h[1]) or 1150 hp Bristol Taurus III or IV for the Polish Air Force (estimated speed 530-560 km/h). Gnome-Rhone engine was delivered only in August 1939, while newest British Taurus was to be delivered in October or November, what was prevented by war, but its development proved long troublesome[1]. Possible alternatives were Polish PZL Waran engine, which was to be ready in spring 1940, 1,000 hp Pratt & Whitney Twin Wasp or 1375 hp Bristol Hercules.[4] As early, as in 1938 Jakimiuk proposed variant with 1100 hp Hispano-Suiza 12Y inline engine, designated PZL.56 Kania, but it was not accepted.
[edit] Fate
By the end of August 1939 there existed: the first flying unarmed prototype PZL.50/I, the second incomplete and engineless prototype PZL.50/II, an incomplete pattern aircraft PZL.50 and parts of four serial PZL.50A. The first prototype had short fairing behind a canopy, all other had long fairing. After the German invasion and outbreak of World War II, on 2-3 September 1939, incomplete aircraft were moved from the factory WP-1 to car workshops at Czerniakowska street in Warsaw, where they were captured by the Germans, and possibly scrapped.
The first prototype was evacuated east - Jan Widawski flew it towards Lwów on 6 September, but it crashed during a forced landing near Rawa Ruska, when the fuel ran out.
Because of the secret surrounding the aircraft, during over 65 years its look was known only partly, from 4 photographs of fragments of the first prototype, made during a presentation to Ciano, two of which are shown in the book 'Polish Aircraft 1893-1939' by Cynk, which also contains drawings of the aircraft[5]. Only in 2005 there were revealed a couple of photographs of incomplete aircraft at Czerniakowska street, made by German soldiers and a Polish amateur [6], what made possible an authentic reconstruction of PZL.50's look.
[edit] Popular culture
The PZL.50/I Jastrząb was the original aircraft used by the Blackhawk Squadron.
[edit] Versions
- PZL.50/I
- First prototype.
- PZL.50/II
- Second prototype with some fuselage shape changes (long canopy fairing) and with simplified engine cowling. [7]
- PZL.50A
- Planned first production batch powered by Bristol Mercury VIII engine (840 hp) and armed with 4 x 7.9 mm machine guns and 100 kg of bombs.
- PZL.50B
- Planned second production batch powered by Bristol Taurus III engine (1145 hp) and armed with 4 x 7.9 mm machine guns, 2 x 20 mm cannons and 300 kg of bombs.
[edit] Operators (planned)
[edit] Specifications (PZL.50/I)
General characteristics
- Crew: 1
- Length: 7.7 m (25 ft 3 in)
- Wingspan: 9.7 m (31 ft 10 in)
- Height: 2.7 m (8 ft 10 in)
- Wing area: 19.4 m² (209 ft²)
- Empty weight: 1,900 kg (4,180 lb)
- Loaded weight: 2,400 kg (5,280 lb)
- Powerplant: 1× Bristol Mercury VIII radial engine, 840 hp (627 kW)
Performance
- Maximum speed: 450 km/h (243 kmots, 280 mph)
- Combat radius: 750 km (405 nm, 466 mi)
- Service ceiling 9,000 m (29,500 ft)
- Rate of climb: 11 m/s (2165 ft/min)
Armament
- Guns: 4 x 7.92 mm PWU wz.36 machine guns
- Bombs: 100 kg
[edit] See also
- PZL.45 Sokół - RWD-25 - PWS-42 - PZL.62
Related development
- PZL.53 Jastrząb II
Comparable aircraft
- Seversky P-35 - Curtiss P-36 Hawk - Bloch MB.150 - Nakajima Ki-43 - Fokker D.XXI - Macchi C.200 - Fiat G.50 - Polikarpov I-180
Related lists
[edit] References
[edit] Notes
- ^ a b c d e f g h Cynk, Jerzy B. Jastrząb ujawniony, p.55-60 (Polish)
- ^ a b c Gruszczyński, Jerzy. Jastrząb nie zdążył... p.46-53 (Polish)
- ^ Cynk, Jerzy B. PZL.50 Jastrząb w prawdziwej postaci ('The PZL.50 Jastrząb in an authentic shape') Skrzydlata Polska, nr. 6/2005, p.59 (Polish)
- ^ a b c Green 1961, p.121.
- ^ Cynk 1971, p. 259-265.
- ^ The photograps as they appear on airwar.ru
- ^ PZL.50 Jastrząb w prawdziwej postaci
[edit] Bibliography
- Cynk, Jerzy B. Jastrząb ujawniony ('The Jastrząb revealed') Skrzydlata Polska, nr. 11/2005, p.55-60 (Polish).
- Cynk, Jerzy B. Polish Aircraft 1893-1939. London, UK: Putnam & Company, 1971. ISBN 0-370-00085-4.
- Green, William. Warplanes of the Second World War, Volume Three: Fighters. London: Macdonald & Co.(Publishers) Ltd., 1961. ISBN 0-356-01447-9.
- Gruszczyński, Jerzy. Jastrząb nie zdążył... Lotnictwo, nr. 12/2005, p.46-53 (Polish).
[edit] External links
- PZL.50 Jastrząb w prawdziwej postaci - article written by Jerzy B. Cynk and published in Skrzydlata Polska aviation monthly
- Samoloty PZL do 1939 roku
- Drawings of various versions of the PZL.50
- Photos and drawing of PZL.50A and 3-d drawing of the PZL.50/I at Ugolok neba
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