PZL.50 Jastrząb (Hawk) was a Polish late 1930s fighter aircraft designed by Wsiewołod Jakimiuk at Państwowe Zakłady Lotnicze.

In early 1930s the Polish Air Force was equipped with the then state-of-the-art PZL P.11 all-metal gull wing monoplanes, the latest of a family of fighter aircraft designed by Zygmunt Puławski.

[1] While potentially a suitable design, the PZL.38 had problems finding proper engines and the estimated performance of the PZL.39 was too low (maximum speed 400 km/h (250 mph)), resulting in both programs being canceled.

At the same time, Rayski selected the British Bristol Mercury VIII (840 metric hp/825 imperial hp) radial engine as the project's powerplant.

The prototype was almost ready by October, but its completion was delayed by the lack of a retractable landing gear, delivered by the British Dowty firm.

Despite being officially classified as a secret, on 27 February it was on static display for the Italian Foreign Minister, Count Galeazzo Ciano.

[3] Tests were carried out mainly by Bolesław Orliński and several other pilots who noted that the prototype, after modifications to the tail, exhibited satisfactory handling and maneuverability characteristics although it was not agile enough as an interceptor.

[7] The Mercury VIII engine had problems with delivering full power due to an unsuitable carburetor intake and, after modifications, the prototype was able to reach 442 km/h (275 mph).

[1] The first prototype was flown east by Jan Widawski towards Lwów on 6 September, but crash landed near Rawa Ruska upon running out of fuel.