Title: The Mi-2 Helicopter
Authors: Michal Fiszer, Jerzy Gruszczynski, and Tomasz Bylica (Translation - Polish to English)
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The hydraulic system provided hydraulic pressure for the hydraulic boosters in the control system. The compressed air system provided air pressure for the main wheel brake system. It included a piston-type compressor and compressed air reservoirs. The fuel system was made up of a rubber main tank located beneath the floor (600 dm3 in capacity), fuel lines, and two electric fuel boost pumps supplying the fuel from the main tank to the engine fuel management systems. Additionally, there was a provision for the installation of external fuel tanks, one on each side of the helicopter, with the capacity of 238 dm3 each. With the external tanks, the total system capacity was 1076 dm3.

Chech Mi-2 Mi-2 of Chech Republic Air Force Taken by: Milosz Rusiecki

As concerns instruments and avionics, the helicopter was equipped with a full complement of basic flight and navigation instruments for operation with and without outside visibility, a VHF transceiver, an ARK-9 radiocompass (ADF), an RW-3 radio altimeter, an HF transceiver with a 100 km range, and an SPU-7 intercom system. Military versions were additionally equipped with the SRO-2 „friend-or-foe" identification system.

One of the first attampts at building an improved variant of the Mi-2 was the Mi-2M helicopter developed in the first half of the nineteen seventies. The aim of the project was to develop a helicopter with a more comfortable cabin (no floor step-up and all seats facing forward) and an improved power margin. Work on the Mi-2M was to be divided into two phases. The first, called the Mi-2M1, involved only a modification of the helicopter's power plant. This was based on the application of modified engines, the GTD-350P, in which greater power output - 331 kW (450 KM) was obtained by increasing the level of gas temperature in the combustion chamber. The GTD-350P engine version, developed at WSK PZL Rzeszów, had some shortcomings, but was generally a success. This was due to the fact that the original GTD-350 had a certain reserve thermal capacity. Limit temperature control was only partially automated, which required more careful instrument monitoring. The Mi-2M1 with the GTD-350P turboshafts was test flown at the beginning of 1974.

In parallel, a team headed by Henryk Czerwinski, MEng., was working on the Mi-2M2, the variant incorporating more extensive modifications to the basic design. In the enlarged (deeper) fuselage of the Mi-2M2 a flat floor (no stepup for fuel tank) was used, which gave greater freedom in the arrangement of seats. This was taken advantage of by having all passenger seats facing forward. Cabin volume increased by 0,9 m3 as compared to that of the standard Mi-2. The arrangement of cabin doors was also changed, with the introduction of an additional passenger door on the starboard side of the fuselage. Both cabin doors were now sliding aft, which facilitated their opening in flight, eg. for rescue operations. The starboard cockpit door remained hinged. The landing gear was modified, extending the struts-cum-shock absorbers upwards, which allowed a wider wheel track. This improved the helicopter's stability on the ground, which was especially important when landing on unprepared sites. Deepening the fesulage downwards permitted the underfloor main fuel tank capacity to be increased, which eliminated the need for external fuel tanks. The fuel supply system, as well as the cabin heating and ventilation system, were also modified. All those changes resulted in greater crew and passenger comfort. Unfortunately, visibility from inside the cabin to the sides suffered in the process.

The first Mi-2M2 was test fown on July 1st, 1974, by Janusz Ochalik. In the course of flight testing it turned out, however, that the flight characteristics of the new helicopter were somewhat worse than those of the standard Mi-2, mainly due to the greater take-off weight. In the years 1974-1975 tests of the modified Mi-2 continued, but ultimately the Mi-2M did not get into series production. The main reasons were the underdeveloped engines; if a good alternative power plant, with greater power rating, were available, the Mi-2M would surely be a better helicopter than the standard Mi-2. Such engines, however, were just not there. Moreover, the potential customer for the helicopter was not very enthusiastic about the proposed modification, in spite of its obvious advantages. In the end, a stop was put to further development of the Mi-2M.

Lithuanian Mi-2 Mi-2 of Lithuanian Air Force Taken by: Milosz Rusiecki

Only one flying prototype of the Mi-2M2 was built (S/N ZD0106). It flew under the civil registration markings of SP-PSO. Probably three units for ground testing were also built. Upon the completion of the test programs they were withdrawn from operation, and then one of them was handed over to the 47th Helicopter Training Wing at Nowe Miasto as a static article to be used in training programs. Another example of the Mi-2M2 is still to be seen in the yard of the Technical School Group in Swidnik.

As has been said before, the Mi-2 was made in many different specialized variants, based on six standard versions. One of the first to be developed was the training version (with dual controls), sometimes called unofficially the Mi-2Sz (and in the USSR the Mi-2U or UMi-2). The first training Mi-2 (S/N 540612038) was test fown on March 25th, 1968, by Major Stanislaw Wiacek and Ryszard Kosiol. Apart from the dual controls, the training version was later additionally equipped with special filters (curtains) for instrument flight training. Orange filters were put on the cockpit glazing, which did not hinder instructor's visibility outwards, while a blue filter was placed on the trainee's helmet, which made it impossible for him to see outwards of the cockpit at all, without impairing his visibility of the instruments. The system was developed at the Institute of Aviation, Warsaw. Later on, the dual controls were employed also on individual examples of other versions of the helicopter, eg. the ag version.

The next was the agricultural version, first test flown at Swidnik on June 20th, 1968, by Stanislaw Gajewski (S/N 520644058). The helicopter was designed for the application of solid agents (powders and granulates) as well as for aerial spraying of liquid pesticides. The Mi-2 helicopter in its agricultural version (unofficial designation Mi-2R) was equipped with hoppers, initially of stainless steel, then of glassfibre composites. The hoppers were installed on he sides of the fuselage and had a capacity of 700 dm3 each. For the application of soild agents, a tunnel-type spreader was installed on the bottom flange of each hopper, with an electric fan for dusting. In the variant for spraying operations, the electric fan was replaced with an electric pump unit, installed at the bottom part of each hopper. The pump units forced the liquid chemicals into special tubular spraying booms (commonly called "rakes") with a large number of spraying nozzles. Various nozzle number combinations were used (typically 2 x 128). Dosage control was from the cockpit, by means of an electro-pneumatic control system.

Polish Mi-2 Mi-2 in liaison version (formed armed variant) with the 49th Combat Helicopter Wing emblem on cabin door. Taken by: Milosz Rusiecki

Apart from the spraying or spreading systems, the agricultural version of the helicopter had also some internal modifications. Among other things, there were changes to the electrical system (new wiring looms and elements of ag systems control), and the compressed air system of the helicopter was also modified.

Apart from the ag variants described above, many specialized ag variants appeared later on, with a variety of specialized equipment kits. Among others, there was a variant with electric atomisers for ULV spraying (dosage rates up to 5 dm3/ha), with centrifugal disc spreaders for solid fertilizers, with spot applicators for operations against the African pest, known as the Black fly, which spread the germs of the so-called river blindness, or with hot aerosol generators, etc.

Agricultural Mi-2 helicopters were manufactured at Swidnik since 1969, solely for export to the USSR. Only in 1975 first attempts were made to use the ag Mi-2's in Poland, initially at the State Farms in the Opole region. Regular operation of agricultural Mi-2 helicopters in Poland began in 1976, although already in 1973 such helicopters, belonging to WSK PZL Swidnik, did contract ag work abroad. The primary operator of the ag helicopters was the Department of Helicopter Operation and Services at Swidnik which, at a certain time, had a fleet of over 100 agricultural Mi-2 helicopters. The Department did aerial ag work in Poland, but also in numerous countries of the world - including Africa and the Middle East. Apart from that, several Mi-2's were operated by Zaklad Uslug Rolniczych, an independent ag services company. In Poland, agricultural Mi-2's were used mainly in the west and north-west districts of the country, where state ownership of land prevailed.

Another specialized version of the helicopter, designed and built as an original development, was the ambulance version. Due to only small changes and modifications with relation to the basic transport version, ambulance helicopters were not distinguished by special serial numbers, their S/N's beginning with „51". In the ambulance version, modifications with relation to the basic transport version were limited to the cabin interior. Cabin equipment included rails for the attachment of two stretchers, which allowed two stretcher patients to be carried. Another two patients or casulaties could be carried on special seats. The last seat was for a doctor or paramedic. Standard equipment of the ambulance version included some basic elements - a first aid kit, an oxygen system, and other basic medical equipment. A more extensively equipped medical version was also developed, some examples of which were delivered to clinics in Poland. The primary operator of the ambulance version of the helicopter were the Ambulance Aviation Groups, gradually set up all over the country. First ambulance Mi-2's were delivered to the Groups in 1972. Eleven years later 30 ambulance helicopters of the type were in operation at 13 Ambulance Aviation Groups, and two years ago, a company known nowadays as the Lotnicze Pogotowie Ratunkowe (LPR), which stands for Air Rescue Service, operated as many as 36 ambulance Mi-2's. The helicopters are used not only to ferry patients between hospitals or pick casulties up from accident sites, bur are used also for mountain rescue operations. That last application has become the specialty of the LPR at Cracow. Moreover, several examples of the ambulance version of the Mi-2 were delivered to the Polish military, where they are known under the designation of Mi-2SR (sanitarno-ratowniczy, the Polish words for ambulance and rescue).

Mi-2URP A group of Mi-2URP (armed with anti-tank missiles, the rails for AT-3 are empty on this picture). Taken by: Milosz Rusiecki

Another production version of the Mi-2 was the passenger version, sometimes referred to as the „executive" version (which obviously was something of an exaggeration). It had the same number of passenger seats as the basic transport version - six on the central couch and one on the aft cabin wall, but the upholstery finish of the seats was much better. Moreover, between the rear-facing couch seats and the seat on the aft cabin wall there was a folding table. The cabin walls had soundproofing lining covered with wall panels. The cabin floor was usually carpeted. Some Mi-2 helicopters left the production line in that version (their serial numbers began with „53"), and then the helicopters were unofficially designated the Mi-2P. The first Mi-2P helicopter (S/N 530322047) was made in April, 1967. It had the registation markings of SP-PSC and was used at Swidnik as both a demonstrator and a company helicopter. At present that helicopter, under the registration markings of SP-SDM, is operated by HELISECO. The first Mi-2P to be delivered to the Polish military aviation, in February, 1968, was an example with the serial number of 530602127 (military markings 0602), made in December, 1967.

One of the first specialized variants for the military was the flying command post helicopter Mi-2D (from the Polish work „dowódczy" - command). Mi-2D helicopters were designed as flying command posts for army tactical groups. The cabin of this variant was completely rearranged. It had three stations for staff and command personnel - two for officers designated by the Division Commander and one for special equipment operator (communications and codes). The specialized equipment of the helicopter included an R-111 VHF transceiver for communication with Army units, an UTS special communications transceiver, an UFK-K-1 radio-telephone, and an MS-61 voice recorder. On the outside, the helicopter could be told apart form ther Mi-2s by the antenna system of the R-111 VHF transceiver - it was a steel cable stretched on two support brackets on the rear part of the starboard side of the helicopter fuselage. Due to the considerable weight of the UTS transceiver, in practice it was frequently removed from the helicopter. The Mi-2Ds were mainy delivered to the division squadrons of the two helicopter wings (49th and 56th Combat Helicopter Wings, at Pruszcz Gdanski and Inowroclaw, respectively).

Serial numbers of the Mi-2Ds began with „57" (the first example), and then „51", like the basic transport version. The command version was manufactured solely for the Polish military, and the total number built was 15 units. The first helicopter in that version was built in December, 1967 (S/N 570607127) and delivered to the 47th Wing of Liaison and Ambulance Aviation at Modlin. It was an experimental machine, its equipment differing from that of later production helicopters. A long period of testing followed, resulting from problems with the selection of suitable communications equipment (due to electromagnetic interference), which caused that the 14 production machines in that variant were built as late as the months of August-October in 1974. The helicopters were delivered to both the helicopter wings (10 units, wihch corresponded to the number of Army Divisions with the exception of the 6th Pomeranian Airborne-Assault Division and the 7th Luzyce Division of Coastal Defnce) and to the liaison squadrons of the Pomeranian and Silesian Area Commands (4 units - 2 each for the 3rd Liaison Squadron at Bydgoszcz and the 11th Liaison Squadron at Wroclaw). The last four of the helicopters were later converted to the chemical contamination detection variant, the Mi-2Ch. In 1977 another 11 units of the Mi-2D were built, almost all of them going to the 49th and 56th Combat Helicopter Wings. From that moment, division commanders could have two Mi-2D helicopters each at their disposal.

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