PZL Bielsko SZD-9 Bocian
SZD-9 bis 1E Bocian
The Bocian (or Stork) tandem two-seater sporting and training sailplane prototype SZD-9 flew for the first time on 11 March 1952.
The Bocian is cleared for cloud flying, spinning and basic aerobatics and was one of the few two-seaters to be stressed for aerobatics, including inverted flight; controls and instrumentation have, from the start, been intended to be suitable for sporting flying as well as training.
Of conventional all-wood construction, the Bocian is distinguished by its mid-set wing swept forward, in the Mk 1E version, by 1°30' at the quarter-chord line and with 4° dihedral. The first production Bocian flew in March 1953 and the type went through several versions; the Bocian 1C first flew in February 1954, the Mk 1D in 1958 and the final version, the Mk 1E, on 6 December 1966. The early versions featured several differences in the tail, and especially the rudder.
SZD-9bis Bocian 1E
Within a few years of first going into production, the type had set several world speed records over 200 and 300km closed circuits, and in 1962 Franciszek Kepka set a world record for a goal flight distance by flying 401 miles (636.6km) in a Bocian. On 5 November 1966 a Bocian 1D flown by the Polish pilots S. Josefczak and J. Tarczon set an international gain of height record for multi-seaters of 38,320ft, while the corresponding ladies' record was set in another Bocian on 17 October 1967 by Adela Dankowska and M. Mateliska, who achieved a height gain of 27,657ft.
An experimental verison of the Bocian was being modified during 1964 for flights at up to 15,000m (49,200ft); this was to be flown as a single-seater with the pilot wearing a special WUK type pressure suit with advanced oxygen equipment. Eight 4-litre (0.87 Imp gal) oxygen bottles, sufficient for up to four hours' flight, were carried in the fuselage, and the cockpit was heat-sealed and provided with R/T radio. At a later stage it was intended to provide heating, double glazing for the canopy and de-frosting of the canopy glass, amongst other improvements, for this special Bocian, and a high altitude pressurized variant with a crew of two was also studied for a time.
The Bocian 1D's wings are of slightly larger span than the Mk 1 E's (59ft 5.5in instead of 58ft 4.75in) and have 3° 30' of forward sweep; the Mk 1D is also 9.75in shorter in overall length than the 1E, and its rudder contours are slightly different to the 1E's. In both versions the wings are two-spar structures with a plywood D-section leading edge and fabric covering; the slotted ailerons are each in two parts, which are separately controlled. No flaps are fitted but there are SZD air brakes inboard of the ailerons. The oval section fuselage is plywood-covered on both versions and the two tandem seats, under a long two-piece blown Plexiglas canopy, are so positioned that the rear seat is over the cg and there is no need to carry ballast when the aircraft is flown as a single seater. There is a non-retractable monowheel with a brake and a shock absorber fitted, and a short nose skid, plus a tailskid. The cantilever wooden tail unit has a trim tab in the port elevator.
The Bocian was to have one of the longest production runs of any sailplane, a total of 620 having been built when production ended at the end of 1977. The type was exported to 33 countries, including the Chinese People's Republic, where licence production of Bocians and several other Polish sailplanes commenced at the Glider Manufacturing Centre at Tchan-Tia-Kou during 1955-56.
PZL Bielsko / SZD 9 Bocian
PZL Bielsko / SZD 9 bis Bocian 1 E
Length: 26 ft 10.75 in / 8.2 m
Wingspan: 58 ft 4.75 in / 17.81 m
Aspect ratio: 16.2
Wing area: 215.28 sqft / 20.0 sq.m
Height: 4 ft 0.25 in (excluding wheel)
Max take off weight: 1190.7 lb / 540.0 kg
Weight empty: 793.8 lb / 360.0 kg
Max. weight carried: 396.9 lb / 180.0 kg
Max. speed: 108 kts / 200 km/h / 124 mph (in smooth air)
Max aero-tow speed: 87 mph
Landing speed: 32 kts / 60 km/h
Cruising speed: 43 kts / 80 km/h
Wing loading: 5.54 lbs/sq.ft / 27.0 kg/sq.m
Min sinking speed: 2.69 ft/sec at 44 mph
Best glide ratio: 26:1 at 50 mph