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PZL-Swidnik History - Helicoper Design

The first aircraft products of WSK Swidnik were assemblies for the MIG-15 jet-propelled fighter manufactured in co-operation with WSK Mielec. The factory first came into contact with the helicopter engineering in 1954 when the series license production of the Mi-1 helicopter (designated SM-1 in Poland) was set up at Swidnik.

The design features of this helicopter were: piston engine propulsion (model AI-26W, the licensed version was under designation LIT-3 (575 shp), metallic-wooden blades of main rotor, friction dampers in the main rotor hub, fuselage of a framework structure covered with sheet-metal skin, direct control (without hydraulic boosters), three-blade tail rotor (with wooden blades) and three-cycle landing gear. The first flight of the first SM-1/300 assembled by Swidnik was made on 23 March 1956. The SM-1/300 was the equivalent version of the Soviet Mi-1T helicopter like the SM-1/600 of the Soviet Mi-1A and the SM-1W of the Soviet Mi-1M helicopter.

The SM-1/600 helicopter first flew on 29 May 1959 while the SM-1W on 28 November 1960. A number of specialized versions were introduced during the SM-1 helicopter production beginning from the air ambulance version with the enclosed nacelles installed outside and designed for transportation of casualties to the SM-1Wb with boosters (first flew on 23 December 1963). The boosted version of helicopter brought significant innovations, such as: all-metal blades of main rotor and hydraulic boosters for rotor cyclic and collective pitch control.

In the years 1957-1960, the SM-1 helicopter was modified. A new version, designated SM-2 was of the changed configuration and enlarged cabin (the first flight on 3 February 1961). The helicopter could accommodate 5 persons on flight deck. Only a limited batch of this helicopter was produced and, next was used by the Polish Army. Further developed from the SM-2, was the medevac version where, contrary to the SM-1 helicopter, the patient was carried inside the cabin (not in the enclosed nacelle). Owing to that, the medical attendance could be provided while in flight. Transportation of the stretcher into the cabin was effected through an open forward part of the fuselage. The SM-2 sea rescue version was equipped with inflatable flotation bags to prevent the helicopter from sinking when emergency landing on the water.

In the years 1958-1959, the original project was realised, i.e. the SM-4 Latka helicopter of design fully devised by personnel reporting to the General Designer of Helicopters. Development activities covered as follows: engineering drawings, calculations and fabrication of helicopter examples for static ground and flight tests. The design features of the SM-4 Latka were: opposed-piston engine propulsion, composite blades of main and tail rotors, fuselage and tail boom (without skin) of framework structure, composite transparent cockpit and composite skid-type landing gear. The project was brought to the ground tests stage but later was halted due to the engine problems, among others.

At the same time the work was being pursued on composite blades for SM-1 and SM-2 helicopters. This activity was completed with releasing a limited batch of blades originally designated L-251, next their variant was known as L-253. In 1959 the blades were introduced into trial service.

In 1965 the licensed helicopter Mi-2 introduced to the series production replaced the SM-1. Design features: two GTD-250 turboshafts, all-metal blades of main and tail rotors, hydraulic dampers in the rotor hub, two-blade tail rotor ("rigid on hinge"), hydraulic boosters in the control system, semi-monocoque fuselage, a comprehensive fit of instruments and avionics.

The forecast availability of turbine engines gave rise to resuming work on the SM-4 Latka in a modified version with the turbine propulsion. The preliminary modification design was under designation SM-4T. The weak point of this predesign was the necessity to throttle the GTD-350 engine power after installation on the "Latka" airframe. Finally, this project has not been approved for further development. In place of this project, the Design Office was given the objective to develop a predesign for a new, light helicopter that would be fit for a single GTD-350 turboshaft. The helicopter predesign was developed between 1964 and 1965 originally under designation SM-6. Unfortunately, this project foundered due to restructure of the company and foundation of the Helicopter Testing Plant.

The Testing Plant developed a number of the Mi-2 helicopter versions. The most significant, with respect to the design changes embodied, was the version designated Mi-2M. This version was developed between 1968 and 1972 and first was flown on 1 January 1974. The Mi-2M fuselage was more functional. Also, an integral fuel tank was provided. This version has been never introduced into the series production, mainly due to excessive weight. However, it had successfully passed all ground and flight tests. Several units were at disposal of WSK Swidnik.

The Mi-2 version that permanently went to the series production was the training version. Other versions were: agricultural with single or dual controls; passenger with single or dual controls, freighter with single or dual controls, medevac with single or dual controls, passenger in VIP configuration, version with TV cameras, version adapted for measuring apparatus of the Telecommunication Institute, agricultural with atomizers for LV or LUV spraying, version adapted for geophysical prospecting work and many specialized military versions.

As a result of the decision on forming branch research & development centers, the existing Testing Plant was converted in 1972 into Transport Equipment Research & Development Center (OBR-SK in short). This Center has overtaken the functions of the former Testing Plant expanded by the series production design activities and a part of the series flight trials.

OBR began the original project of the PZL Sokol helicopter. The activities were carried on in collaboration with the Moscow Helicopter Plant and supported by subcontract programs with other WSK factories in Poland. The first work covered: engineering design in the form of engineering drawings, helicopter mock-up, prototype for static, fatigue ground and flight tests. Basic design features of the PZL Sokol: increased load-carrying capacity when compared with the Mi-2, powerplant composed by two-turboshafts upgraded by OBR NL Rzeszw based on the Soviet aircraft engine, four-blade main rotor, three-blade tail rotor, composite blades of both rotors, horizontal stabilizer, rocker-type kinematic linkage of the landing gear. Today, the PZL W-3A Sokol is the main product offered by PZL.

A half-prototype modification version of the Mi-2 helicopter was designated PZL-Kania. Modification constituted in installation of a new powerplant in place of the former GTD-350 turboshaft. The modification activities have been conducted since 1978. The most important design features and modifications of PZL-Kania are: two-Allison C20B gas turbine engines, a fully articulated three-blade main rotor, two-blade tail rotor (all blades are composite and equipped with the electrical anti-icing system). The cabin can accommodate up to 10 passengers including a pilot. The additional baggage compartment of 0.4 m3 in volume is accessible from inside the passenger cabin.

The cabin can accommodate up to 1200 kg of internal cargo. The helicopter can-carry slung loads up to 800 kg using the external cargo sling. It is provided with the Bendix/King avionics or other if requested by a Customer, doubled DC supply system, engine cowlings of modified shape, deflector reducing the helicopter vibrations, new design concepts implemented in the transmission system and other helicopter systems, engine control and powerplant monitoring systems that increase the safety of operation and reliability while in flight. The first flight of PZL Kania was on 3 June 1979.

PZL Swidnik was also the manufacturer of the PZL ML-1 powered hang-glider having as the only aircraft of such a type the Polish Type Certificate granted on 17.06.1993. Design features: ROTAX 5032V two-stroke, two-cylinder air-cooled engine of 496.7 cc made by the Austrian BOMBARDIER ROTAX company, 37 kW power (50 shp), 6500 rpm. Further design features are: manual rope-type engine starting, three-blade composite push airscrew of pitch adjustable on ground, load-carrying capacity of 200 kg and the maximum take-off weight of 345 kg. Recently, the production of this powered hang glider has been assigned to another manufacturer.

In November 1991 the company began the project aimed at designing a completely new, compact light, single turboshaft multipurpose helicopter, PZL SW-4. So far four prototypes have been built, two for ground tests and two are flying prototypes. The first flight was made by the prototype No. 3 on 29 October 1996. The PZL SW-4 helicopter (MTOW of 1800 kg) is able to carry up to 5 persons (1 pilot and 4 passengers). Intended versions include: training, passengercargo, transport, EMS, border patrol and military. Design features: one Rolls-Royce Allison 250-C20R turboshaft, transmission rating 336 kW (450 shp) for take-off, three-blade main rotor and two-blade tail rotor. All rotor blades are GFRP/epoxy made, skid-type landing gear, airframe components are mainly of aluminium alloy and GFRP/epoxy. The helicopter has rearward-sliding doors on each side of cabin and one front hinged door. The door construction, without a centre pillar, provides for convenient access to the cabin. The baggage compartment of 0.85 m3 in volume is aft of the passenger cabin. The helicopter is equipped with the Bendix/King avionics for VFR and IFR flights, day and night. Type certification and introduction into the series production are planned during 2002.

PZL-Swidnik is the sole manufacturer of the PW-5 single-seat glider designed by the Aircraft Composite Structure Scientific Research Group at the Warsaw University of Technology. It is the latest Polish glider, winner of the "World-Class Glider" competition announced in 1993 by FAI. The PW-5 is all-composite glider (glass-fibre epoxy). Performance: max. gliding ratio: 33 (at speed of 80 km/h), never exceed speed: 220 km/h, ring span: 13.44 m, empty weight: 190 kg, allowed gross weight (in flight): 300 kg. The latest aircraft produced by PZL-Swidnik is a two-seat glider designated PW-6. Performance: max. gliding ratio: 34 (at speed of 95 km/h), never exceed speed: 260 km/h, wing span: 16 m, empty weight: 340 kg, allowed gross weight (in flight): 530 kg.

The next aircraft, production of which is planned to be located at Swidnik is a four-seat all-composite I-23 airplane. The General Purpose Airplanes Plant at the Aviation Institute in Warsaw originally devised the design. It is a single-engine, low-wing monoplane with conventional flying controls, three-cycle retractable landing gear and dual controls. Upwards-opening door, on each side, provide for free access to a four-seat cabin. The structure is mainly composite (GFRP/CFRP) epoxy with sandwich skins including aramid honeycomb core. Attachments made of alloy steel. Wing ribs made of duraluminum. Power plant: one 180 shp 4-cylinder Lycoming 0-360 engine. Hartzel two-blade tail rotor of constant rpm. The airplane is equipped with the Bendix/King avionics allowing IFR flights. Take-off weight: 1050 kg, never exceed speed: 315 km/h, cruise speed: 280 km/h, max. range: 1430 km. The I-23 airplane may be intended for private owners with the view of fast and long-distance travelling, for flying clubs or flight schools for training pilots in IFR flights. In October 2001 PZL I-23 was granted Polish type certificate.



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