WSK PZL Świdnik SM-4 Łątka. 1962 - History

Category: Helicopters Last change: September 2019 History Construction Tally

Kraków September 30. 2018.

179b Section 1962

WSK PZL Świdnik PZL SM-4 Łątka 



WSK PZL Świdnik SM-4 Łątka. Photo LAC

WSK PZL Świdnik SM-4 Łątka. Photo LAC

WSK PZL Świdnik SM-4 Łątka. Photo LAC


Świdnik is a city in Poland associated with aviation since 1934. The air factory called WSK PZL Świdnik was built here in 1950.

WSK PZL Świdnik – Wytwórnia Sprzętu Komunikacyjnego, Państwowe Zakłady lotnicze, Świdnik. 

Świdnik is an important place in the world where helicopters were built and its are still being produced. Initially, parts and subassemblies for the production of PZL Lim-1 fighter aircraft were manufactured at WSK PZL Świdnik. Over time, the factory has specialized in the production of helicopters. The factory began with the production of Mil Mi-1 helicopters, mounted here under license from CCCP. The helicopter received the Polish designation SM-1. The factory crew gained a lot of experience, which allowed to build a new helicopter designated SM-2. The SM-2 helicopter was created in a construction team led by engineer Jerzy Tyrcha. The SM-2 has more transport capabilities than SM-1.

The next helicopter, whose production was launched in Świdnik, is Mil Mi-2, was to be designated SM-3. However, the Soviets didn’t agree to the name SM-3, and the helicopter was marked Mil-Mi-2.

In 1955, the Aviation Construction Center (Ośrodek Konstrukcji Lotniczych ) was created in the factory, which later changed its name to the Research and Development Center of Communication Equipment (Ośrodek Badawczo-Rozwojowy Sprzętu Komunikacyjnego). His employees dealt with new technologies.

In the years 1960-1963, a light helicopter PZL SM-4 "Łątka" was developed at the Aviation Construction Center. Łątka is Polish Dragonfly. The team of constructors working on the new helicopter was led by engineer Jerzy Kotliński. The SM-4 Łątka program wasn’t a priority program and was treated as an additional task. The financing of the program was insufficient. The 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: communication, school, sanitary and agricultural.

The PZL SM-4 Łątka was a three-seat, light, short-range helicopter powered by a reciprocating engine. Engine power about 200 hp. The total mass of a 1,000 kg. The helicopter was designed in a classic Sikorsky system. It was built of metals and laminates. It was equipped with a single three-bladed glass-fibre main rotor and a two-bladed tail rotor. Powered provided by a Narkiewicz WN-6S air-cooled flat-six horizontally-opposed piston engine, which was mounted behind the cabin. The pilot and two passengers were accommodated in an enclosed cabin with extensive glazing. The tail rotor was carried on the end of an open tail boom constructed of welded steel tube. The tail boom is similar to the tail beam of the Polish BZ-4 Żuk helicopter. The undercarriage consisted of two skids.

The assembly of the PZL SM-4 Łątka prototype was completed in 1962. Flight tests on the helicopter a tether were conducted 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, the test pilot Antoni Śmigiel died, and several other people suffered injuries. The PZL SM-4 Łątka tests were not successful. The helicopter had strong vibrations. The Narkiewicz WN-6S engine was overheated because air-cooling was inefficient. Constructors expected that cooling would be efficient during a normal flight. Nevertheless, the engineers have developed a larger fan. The WN-6S engine hasn’t approved for flight use.

In 1963, the government in Warsaw limited the financing of new technologies and the PZL SM-4 Łątka program was closed. The helicopter PZL SM-4 Łątka never performed an independent flight. The only prototype stood in the factory until 1969, and then it 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 receive the designation SM-5 (SM-4GTD). The project has not been 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 the helicopter. The first engine was made at the end of June 1961, and in July 1961 tests began. Tests in a special position were conducted until June 1962.


Written by Karol Placha Hetman