Archive digitization



Aviation and Diplomacy

Frank Piasecki

NATO 1949-2009 Projekt ekspozycji w Muzeum Lotnictwa Polskiego w Krakowie



Polish Aviation Museum

31-864 Kraków,
al. Jana Pawła II 39
phone: (12) 640 99 60,
(12) 642 40 70
e-mail: info@muzeumlotnictwa.pl

a cultural institution of the Malopolska Region

Małopolska – Kraków Region


Patronage

Kraków Airport







Glider: IS-4 Jastrząb 'SP-1391'

IS-4 Jastrząb 'SP-1391'
Poland
aerobatic glider
1953



  • Technical data


Span 12.0 m (39 ft 4 in)
Length 6.25 m (20 ft 6 in)
Wing area 13.75 sq m (148 sq ft)
Empty weight 255 kg (562 lb)
Take-off weight 340 kg (750 lb)
Glide ratio 19.6 at 82 kph (51 mph, 44 kt)
Sink rate 1.08 mps (3.5 fps) at 73 kph (45 mph, 39 kt)
Minimum speed 62 kph (39 mph, 33 kt)
Max. diving speed 450 kph (280 mph, 243 kt)

 

A single-seat all-wooden aerobatics glider of shoulder-wing cantilever monoplane configuration.

The construction and the aerodynamic design of the Jastrząb (eng. hawk) was worked out by engineer Józef Niespał in 1948–1949 at the Gliding Institute in Bielsko-Biała. The completion of the factory drawings took half a year. The prototype flew in December 1949. It featured very good flight characteristics, though to perform aerobatics it had to be accelerated by a diving flight. Strong construction and good aerodynamics allowed the glider to exceed the speed of 500 kph during test flights.

In April 1952, series production of 10 gliders started at the Experimental Gliding Institute (previously the Gliding Institute) in Bielsko-Biała. Another series of 25 gliders was produced in Krosno in 1953. Three IS-4 Jastrząbs were exported to the People's Republic of China and to the German Democratic Republic. Thanks to its virtues, Polish aero clubs retained the Jastrząb through many years – until the end of the sixties. During air shows organized in those years the appearance of the Jastrząb always guaranteed an unforgettable spectacle of aerobatics.

The IS-4 Jastrząb factory number 17 registered as SP-1391 was manufactured in 1953. It was operated by the Subcarpathian Aero Klub at Krosno. In 1964 it was included in the Polish People's Republic Twentieth Anniversary Exhibition in the newly established aviation museum in Kraków.

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