Kraków 2018-09-05
179b Section 1962 year
WSK PZL Świdnik PZL SM-4 Łątka
WSK PZL Świdnik PZL SM-4 Łątka is a Polish helicopter developed in Świdnik. The helicopter was powered by a 6-cylinder piston engine. Only one prototype was built.
The history of the SM-4 Łątka helicopter.
Świdnik has been associated with aviation since 1934. The WSK PZL Świdnik aviation factory was built here in 1950. It was named WSK PZL Świdnik - Communication Equipment Factory, State Aviation Works, Świdnik.
Świdnik is an important place in the world where helicopters have been built. Initially, parts and components for the production of PZL Lim-1 fighter aircraft were manufactured at WSK PZL Świdnik. Over time, the factory specialized in the production of helicopters. The factory started with the production of Mil Mi-1 helicopters, assembled here under a license from the CCCP. This helicopter received the Polish designation SM-1. The factory crew gained a lot of experience, which allowed them to build a new helicopter marked SM-2. The SM-2 helicopter was built in a construction team led by Eng. Jerzy Tyrcha. SM-2 has greater transport capabilities than SM-1.
Another helicopter, the production of which was launched in Świdnik, was the Mil Mi-2, which was to be marked SM-3. However, the Soviets did not agree and the helicopter remained marked Mil-Mi-2.
In 1955, the Aviation Construction Center was established in the factory, which later changed its name to the Communication Equipment Research and Development Center. His employees dealt with new technologies.
In the period 1961-1963, a light helicopter SM-4 Łątka was developed at the Aviation Construction Centre. The team of constructors working on the new helicopter was led by mgr. Eng. Jerzy Kotlinski. The SM-4 Łątka program was not a priority program and was treated as an additional task. Funding for the program was insufficient. PZL SM-4 Łątka was the first completely original helicopter project developed in Świdnik. The helicopter was planned to be made in the following versions: liaison, school, sanitary and agricultural.
PZL SM-4 Łątka was a three-seat, light, short-range helicopter, powered by a piston engine. Engine power about 200 hp. The total weight of the helicopter is 1,000 kg. The helicopter was designed in a classic Sikorsky type layout. It is made of metal and laminates. It was equipped with a single main rotor with three fiberglass blades and a two-blade tail rotor. The helicopter was powered by an air-cooled, six-cylinder Narkiewicz WN-6S piston engine, which was mounted behind the cockpit. The pilot and two passengers take place in a closed cabin with large glazing. The tail rotor was placed at the end of an open tail boom constructed of welded steel tubes. The tail boom is similar to the tail boom of the Polish BŻ-4 Żuk helicopter. Fixed landing gear consisting of two skids.
The construction of the PZL SM-4 Łątka prototype was completed in 1962. Tethered flight tests of the helicopter were carried out at the turn of 1962/1963. The tests were carried out remotely from a hidden position (bunker), because during the tests of another Polish helicopter JK-1 Trzmiel, test pilot Antoni Śmigiel died and several other people were injured. The PZL SM-4 Łątka tests were not successful. The helicopter had strong vibrations. The Narkiewicz WN-6S engine was overheating because air cooling was inefficient. The designers expected the cooling to be efficient during normal flight. Despite this, the engineers developed a larger fan. The WN-6S engine was not approved for use in flight.
In 1963, the government in Warsaw limited funding for new technologies and the PZL SM-4 Łątka program was closed. The PZL SM-4 Łątka helicopter has never made an independent flight. The only prototype stood in the factory until 1969, and then was dismantled.
In 1964, in Świdnik, the team of engineer Stanisław Trębacz began a study on the installation of the GTD-350 turbine engine in the SM-4 helicopter. The helicopter was to be designated SM-5 (SM-4GTD). The project was not approved by the government in Warsaw.
The WN-6S engine was developed by engineer Wiktor Narkiewicz in 1958. The engine was a variant of the WN-6B engine, adapted to drive a helicopter. The first copy of the engine was made at the end of June 1961, and in July 1961, tests began. Tests on a special stand were carried out until June 1962.
Construction.
The PZL SM-4 Łątka helicopter is made of metal (steel) and composites (glass laminates). The following components were made of composites: main rotor blades, crew cabin shell, skid-type landing gear elements, tail boom stabilizer and tail rotor. Three-bladed rotor. The blades had a structure made of laminate. Girder made of laminate with a polystyrene core. Flowing parts made of honeycomb filler were attached to the core. The whole thing is covered with laminate. The blades had steel fittings at the base for connection to the rotor head. The fittings had the ability to move vertically and horizontally for control. Two-bladed tail rotor. Made in the same way as the main rotor. The tail rotor drive shaft was located above the tail boom. The drive shaft consisted of five sections connected by joints.
The helicopter is made of three main sections: cabin, middle part, tail boom. The skeleton of the cabin is made of laminate. The windows are made of organic glass. The cabin was attached to a beam that formed the floor and was made of duralumin. The floor of the cabin was connected to the lattice of the central part by means of four fittings. The middle part of the helicopter was a truss made of steel pipes connected by welding. In this part, the final drive, engine with fan, fuel tank and others are mounted. The tail boom was a truss made of steel tubes.
Skid chassis, fixed. Skids were made of duralumin tubes.
WN-6S flat-type piston engine with a take-off power of 132 kW (180 HP).
Data T-T PZL SM-4 Łątka:
Fuselage length: 9.30 m. Height 2.80 m. Rotor diameter: 10.00 m (32 ft 10 in). Main rotor area 78.5 m2 (845 m²). Curb weight: 640-660 kg (1,455 lb). Payload: 340 kg. Take-off weight: 970-980 kg. Maximum takeoff weight: 1,000 kg (2,205 lb). Maximum speed: 115 km/h (71 mph, 62 kn) (estimate). Range: 300 km (186 mi; 162 mi) (estimate). Service ceiling: 3,300 m (10,800 ft) (estimate). Rate of climb: 4.4 m/s (870 ft/min) (estimate). Flight time: 3 hours 20 minutes (estimate). Powerplant: 1 × WN-6S air-cooled, six-cylinder, opposed-rotating piston engine, 130 kW (180 hp). Crew: 1 + 2.
Tally.
One prototype was built.
Written by Karol Placha Hetman