SZD-19 Zefir
The SZD-19 Zefir (Szybowcowy Zakład Doświadczalny - Glider Experimental Works) is a single-seat glider aircraft that was designed and built in Poland from 1957.
Development
Intended to replace the SZD-8 Jaskółka as the Polish team mount at the World Gliding Championships in 1958 in Leszno, the SZD-19 Zefir was a high-wing glider with a wooden and glass-fibre fuselage, retractable undercarriage and all-metal wings incorporating hydraulically actuated flaps. It was designed by a team headed by Bogumił Szuba. The first prototype SZD-19X Zefir flew on 31 December 1958, missing the 1958 championships, but the flight tests revealed problems with control and stability as well as operation of the flaps and complexity of the hydraulic system.[2] The SZD-19 was totally re-designed with all-wooden wings, revised fuselage and tail section, and towing hook relocated to the retractable undercarriage chassis,[3] designated as the SZD-19-2 Zefir 2, first flying on 11 March 1960, showing a marked improvement over the Zefir. Two prototypes of the Zefir 2 were built, flying in the 1960 World Championships at Köln in Germany to gain second, piloted by Edward Makula, and third, piloted by Jerzy Popiel, places in the Open class.[4] With significant success in the World Championships, the SZD-19-2 was refined with new stabilisers and landing gear to become the SZD-19-2 Zefir 2A, flying for the first time in 1962, in time for the 1963 World Championships, held in Argentina, where Makula and Popiel took first and second places.[5] As a result of these successes, demand for the SZD-19-2 was significant with 14 units built, most being sold to other countries.[1](according to some sources, 20 -19-2A units were constructed.[6]). Some of those units were modified to include a braking parachute; they were designated as 'Zefir 2B'. Several records were established by the Zefir 2A/B's, including; a flight distance of 714 km (444 mi) and a 100 km (62 mi) closed triangle speed record of 102 km/h (63.4 mph).[7] To improve the performance, further development with wings extended to 19m was carried out as the SZD-29 Zefir 3, of which two prototypes were built, and the Open-class 19m SZD-31 Zefir 4 of which three were built. Two SZD-31 Zefir 4's competed in the 1968 World Gliding Championships at Leszno with mediocre results - they took 14th and 28th place.[8]
Variants
- SZD-19x Zefir – The first prototype with metal wings and hydraulically actuated flaps, one built
- SZD-19-2 Zefir 2 – Two prototypes of re-designed Zefir with wooden wings, manual flap operation and other improvements. Took second and third places in the 1960 World Gliding Championships - Open class
- SZD-19-2 Zefir 2A – Production version of the Zefir 2 with minor improvements, 14 built[1]
- SZD-19-2 Zefir 2B – Designation change after modification to fit a braking parachute
- SZD-29 Zefir 3 - With a 19m wing this Zefir was optimised for long-distance high-speed flight with minimum sink of 0.66 m/s @ 100km/h and L/D of42 @ 84km/h. The first prototype (SP-2465) flew on 26 April 1965, piloted by Stanisław Skrzydlewski.[1] A second prototype was also built.[9]
- SZD-31 Zefir 4 - A refinement of the Zefir 3, with similar dimensions and performance. Three aircraft were built.
Specifications (SZD-19-2 Zefir 2A)
Data from http://www.piotrp.de/SZYBOWCE/pszd19_2.htm
General characteristics
- Crew: 1
- Length: 7.3 m (23 ft 11 in)
- Wingspan: 17 m (55 ft 9 in)
- Height: 1.64 m (5 ft 4.5 in)
- Wing area: 14 m2 (150.7 ft2)
- Aspect ratio: 20.6
- Wing profile: NACA632-515
- Empty weight: 330 kg (7278 lb)
- Gross weight: 415 kg (915 lb)
Performance
- Maximum speed: 220 km/h (137 mph)
- Stall speed: 71 (clean) km/h (44 mph)
- G limits: +6 / -3
- Maximum glide ratio: 34.5 @ 95 km/h (51.3 kts / 59 mph)
- Rate of sink: 0.83 m/s (163 ft/min)
See also
- Aircraft of comparable role, configuration and era
References
- Taylor, J. H. (ed) (1989) Jane's Encyclopedia of Aviation. Studio Editions: London. p. 29
- "Modelarz" No 4 / 60 (April 1960)
External links
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