Let L-410 Turbolet is a transport and transport aircraft capable of landing at small and unmodified airports. For its robustness, durability and safety, pilots are a very popular aircraft, which has earned the nickname flying jeep. Although primarily designed for regional transport, the ILS CAT 1 electronic instrumentation system and instrument certification allow it to operate in extreme conditions from -40 ° C to +50 ° C. In 1972, the machine also appeared in an episode of Mimicry, a propaganda television series of 30 cases of Major Zeman.
At the turn of the fifties and sixties, Aeroflot demanded from Let Kunovice aircraft with a capacity of 10 to 12 people, which was to replace the more than ten years old Antonov An-2. A study of the high-wing aircraft of a two-engine concept meeting the capacity requirements of the L-400 was developed, which considered the use of piston engines with a power of 735 kW. The advent of light turboprop engines on the market in the mid-sixties, however, allowed designers to rework the original study and under the leadership of chief designer Ing. Ladislav Smrček to start development under the new name L-410. The final form of the machine was processed in 1966-7 and already counted with a large variability of further use. In early 1967, a full-scale wooden model of the fuselage was completed to assess the interior ergonomics and fine-tune the cockpit layout. After completion of the documentation in April 1968, the construction of the first three prototypes was started, the second of which was intended for the breaking test.
As a power unit were purchased engines Pratt & Whitney Canada PT6-A27 526 kW with three-blade propellers Hamilton 23LF-343, later replaced by the type Hartzell HC-B3TN-3D. The first take-off XL-410 was carried out despite the bad weather on 16 April 1969 factory pilots Vladimir Vlk and Ing. František Svinka, the whole flight lasted 45 minutes. The first, third and fourth prototypes served as demonstrators at home and abroad exhibitions. The machines were presented at the Paris Le Bourget ’69 Air Show, the following year in Hannover, Frankfurt, Malmö, Ängelholm and at the Engineering Fair in Brno.
The fate of the first prototype with registration OK-60 is very interesting and intricate. On behalf of Matilda, just before the flight, this machine was christened by the chief designer Ing. Ladislav Smrček together with both factory pilots Vladimír Vlk and Ing. František Svinka. Already 17th May, the aircraft was issued at the international airport Prague-Ruzyně certificate of competence and matriculation OK-YKE. Ten days later, the plane flies abroad for the aforementioned prestigious Paris Air Show Le Bourget ’69. After his return, he was used for the installation of temporary models of interiors of the service, medical, cargo and airborne versions. Subsequently, it served occasionally on routes to Prague Ruzyně, Letňany or Kbely, on accompanying flights in the supply of aircraft to customers or sightseeing flights organized by the Slovak Aeroclub Kunovice. The machine last looked in the air on 13 November 1974, when it was again driven by the same pilots as the day of flight. Matilda after her last landing reached 1648 takeoffs with a raid of 927 hours and 20 minutes.
The next stage in the life of the prototype leading to placement in the Aviation Museum in Kunovice was very thorny for the machine. In 1978, it was placed in an incomplete state in the collection of discarded aircraft on the factory premises, where it was kept by a bunch of mechanics around the founders of the museum. At the end of 1983 it was installed in the company nursery Na Bělince, where erosion and the children themselves contributed to its further devastation. At the beginning of 1991 his condition was so bad that for safety reasons it had to be removed from the nursery land. The disassembled aircraft was then transported and placed in the current premises of the museum, where it is located today. After 1992, the state of the prototype was critical and threatened to scrap. He was saved from this unfortunate end by the help of volunteers, mechanics Robert Pinkava and Zdeněk Svoboda, who repaired the most damaged parts. In the spring of 2019, the Aviation Museum team led by Martin Hrabec in cooperation with SimplyFin s.r.o. and Aircraft Industries a.s. the most extensive renovation yet. Matilda was again given her original white appearance, registration and her “paper” name on her right side and was presented to the public on the fiftieth anniversary of her first take-off.
Start of production
During the flight tests of the first verification series, several design modifications of the airframe took place. One of the most significant was the redesign of the original landing gear, which had certain disadvantages in crosswinds. The chassis now had a wider track with less ground clearance and a retraction system, which now tilted to the axis of the fuselage instead of forward. Furthermore, the fuel tank was enlarged and a small keel was created under the rear of the fuselage, which increased the stability of the aircraft and reduced its sensitivity to crosswinds. A total of five machines were modified in this way, which were hereinafter referred to as L-410. The first manufactured machine from this series never got into the air and was used for breaking tests, the second remained the property of the Kunovice Flight and the remaining three (OK-ADO, -ADN and -ADQ) were put to the SlovAir verification operation for testing.
The L-410A version was characterized by other modifications, especially the strengthening of the airframe, which led to an increase in the maximum takeoff weight to 5,700 kg. Furthermore, in the reinforcement of the coating of the horizontal tail surfaces, the installation of Hartzell propellers and, since 1974, also the change of the original liquid de-icing system of the leading edges of the wings and tail surfaces of the TKS type to the pneumatic Kkoholér-Colombes (Goodrich system). The pneumatic system was also used in the first and third prototypes. Four serial pieces of L-410A from the total production of 25 machines manufactured or modified to this standard underwent extremely demanding tests in the USSR under extreme weather conditions and at air temperatures from -40 ° C to +44 ° C. The machines from the pre-series series were additionally rebuilt for variant A in the years 1973-5. In April 1972, one copy of this version was shown in Moscow to representatives of Aeroflot, then still with MS. license plate OK-CKA. Less than a year later, he flew with the registration CCCP-67251 as the first aircraft of the L-410 series for a Soviet customer. The excellent results of the above-mentioned extreme tests, including all the following, are evidenced by the fact that the L-410 series aircraft were the only type of foreign design and production in the fleet of the then Aeroflot.
The first prototype L-410M took off with the crew of Vladimír Vlk and Ing. František Svinka on November 30, 1973. After the completion of the development of the Czechoslovak Walter M601 engine in Motorlet n. P. (Today’s GE Aviation Czech s.r.o.) and the subsequent launch of its production in 1975, they replaced the original Canadian PT-6 in gondolas. The new engines were equipped with three-bladed propellers of domestic production Avia V508 (today’s Avia Propeller s.r.o.) and such equipped machines began to be referred to as L-410M, MA and MU. The first user was the Czechoslovak Air Force, which served 7 aircraft until 1996. In 1984-86, overhauls began to carry out conversions to the L-410MU, which is a variant that includes some modifications from the L-410UVP, which was already in mass-produced at the time. It was mainly the automatic flagging of propellers, automatic tilt control, injection of cooling water into the compressor and other modifications. The equipment and structural elements of the individual building groups L-410M gradually adapted to the requirements of the Soviet customer, who was at that time practically the exclusive customer.
UVP era begins
Various modifications and improvements, however, ceased to meet various individual demands and therefore the Soviet side then turned to Kunovické designers with a request for aircraft of extraordinary qualities. The machine should be able to operate at the smallest airports without paved surface, moreover, in extreme climatic conditions. In order to meet the requirements of the aircraft, it was necessary to advance the development of the L-410 series and make numerous changes in its design. The answer to these requirements became the L-410UVP whose prototype first flew in November 1, 1976 and which was constructed according to the then new Soviet regulations NLGS-2. The letters UVP are the Russian abbreviation for machines capable of short take-off and landing, which was one of the main requirements of the customer.
Compared to the previous variants, this version of the fuselage is longer by 87 mm and 18 mm higher, the span has increased by two meters, the stabilizer has been adjusted to + 7 °, air brakes have been installed on the upper wing and interceptors have been added. wing side). In addition, the Automatic Bank Control area has been added to the automatic feathering system, which automatically opens when one engine fails, but only at speeds of 205 km per hour. The entrances to the aircraft were also changed. Instead of a front door, an emergency exit was installed with the rear door open, and the main door now had greater clearance for easier access and exit. Initially, it was assembled engines M601B, which were later replaced by M601D engines with propellers V508D. The air inlet on the engine nacelle has also been enlarged, the rear of which has been simplified and shortened. During the series production there were other major changes, including at least the installation of electrically heated quartz windshields of the cockpit, the use of pressurized hydraulic installation, hinged front cover and other modifications. The aircraft carried 15 passengers and was able to detach from the ground after approximately 456 meters.
On this platform was also a military version of the L-410T designed for paratroopers, cargo transport and ambulances. The first take-off took place with the crew of František Srnec and Ing. Frantisek Svinka 8.11.1982. A total of 24 transport and airborne pieces were produced, which were delivered mainly to the Czechoslovak and Libyan Air Force. In 1974, a special photogrammetric version of the L-410AF was produced for the Hungarian operator, which was drowned on 6 August 1977 in Lake Balaton. For the Czechoslovak Air Force was made several years later, seven pieces of more advanced variant of the L-410FG, whose first piece was flown by the crew of Ing. Vladimír Vlk and František Svinka.
In the early 1980s, the largest customer was offered the upgraded L-410 parameters, developed under the leadership of Ing. Ladislav Smrčka. The Kunovice enterprise thus responded to the growing emphasis of the economics of transport aircraft operations worldwide. These criteria included, in particular, an increase in range, maximum take-off mass and increased passenger capacity. Other features were increased engine life, upgraded instrumentation and reduced external and internal noise using five-blade propellers. Unfortunately, the majority of the public still think that these propellers have been chosen for this type of machine in order to achieve higher performance. However, the new version, referred to in the preliminary study as the L-410E, did not provoke a binding interest in the client and so the construction work could not start fully until two years later. In terms of the extent of changes planned for the new version was actually a new type. The prototype was in the initial phase marked as L-420 and under this acronym was also introduced on the Holešské airshow in September 1984. It was a UVP variant with developmental five-blade propellers and dummy fuel tanks at the ends of the wings. Only later, for various political-commercial reasons and unnecessary servility to the Soviet customer, the type designation stabilized on the abbreviation L-410UVP-E.
The first prototype of the L-410UVP-E flew on 30 December 1984 František Srnec and Stanislav Sklenář, and compared to the UVP version has undergone many changes. Transport capacity increased to 19 passengers, thanks to the location of two external drop-shaped 200-liter tanks at the ends of the reinforced wing increased range, increased take-off weight from the original 5800 to 6400 kg and the installation of portable breathing apparatus could be up to 4200 meters. In addition, the electrical installation was complemented by two more generators for windshield heating and defrosting of propeller blades and maximum deflection of the two-slot flaps increased to 41 degrees. In the nacelles were installed Walter M-601E engines with an output of 560 kW, which powered five-blade V510 propellers with both manual and automatic feathering system. Serial production began in early 1986 and the interesting thing is that the first aircraft produced from this 16th series was first presented before the Aeroflot in Moscow with the Czechoslovak registration OK-RZI and only then taken over by the customer with the newly assigned matriculation CCCP-67561.
In the late eighties, one of the first prototypes of the L-410UVP-E was upgraded to the future variant of the L-410UVP-E20 and certified according to Western Western regulations. It was newly equipped with exits under the wings, the rear side of the rear luggage compartment door and the ends of the wing added removable external tanks. Western avionics, autopilot, Bendix / King navigation were built and powerful M-601E engines with V510 propellers were again chosen for propulsion. This modified prototype has undergone numerous exhibitions around the world at the beginning of the 1990s, including the Paris Le Bourget ’91 Air Show. Shortly after it began mass production, which is still ongoing and is today the most widespread and longest produced version. The L-410UVP-E20 still meets today’s demanding customer requirements and meets 17 different certifications.
Mining of snow and water landing areas
In 2014, the development of removable skis for the landing gear of the aircraft began, which was successfully tested in April 2017 at a Russian base 100 km from the North Pole. UZGA Director Vadim Badecha, 26 July 2018, announced at a press conference the successful completion of the development of this ski landing gear, as well as new knowledge and advances in the development of float chassis, which was also involved in the Moscow Aviation Institute (OSKBES MAI).
Testing the L-410UVP-E20 with floats was in early summer, first started taxiing tests at a private “water” airport Volžanka and already in August the aircraft odbyl his first successful take-off with this undercarriage. With this landing gear, the aircraft can land on the water surface with waves up to 0.5 meters, sea level 2 (according to WMO), and can rotate at a radius of 50 meters at sea. It is also equipped with all necessary equipment for operation on the water surface (anchoring set with ropes, portable pumps, …). Assembly of floats can be done in one day, but for successful conversion it is necessary to modify the airframe in the factory. Lowering to water is carried out similarly to smaller ships using a special chassis, which is then pulled back to the paved surface. So far the only existing machine of this configuration with registration RF-67758 was presented to the general public for the first time at the professional exhibition of amphibious aircraft in Gelendek from 6. September 2018. Both undercarriage conversions (skis and floats) are to be produced in the future exclusively by Russian companies and assembled probably in the Russian Yekaterinburg, where to move part of the production of aircraft L-410.
In 1991, the Polish crew with Captain Keson on the L-410UVP-E with SP-FGK registration marks crossed the Atlantic Ocean for the first time. For this demanding flight, the machine was equipped with large tanks (installed in the passenger compartment), which could hold up to 3,500 liters of fuel. Other crossings across the Atlantic were carried out either via the northern route from Europe via Iceland, Greenland to North America, or via the southern route, again from Europe via Africa to South America.
In 1995 the pilots Stanislav Sklenar and Ing. Svatopluk Vlček escaped from the road when they piloted the L-420 with the matriculation OK-XYA landed on the Australian island of Lady Elliot with an area of only 0.45 km². The local 22 m wide grassy-sandy, very bumpy and dusty airport runway is only two meters above sea level and with its length of 608 m divides the visible surface of the island (about 1/3 of the total area) into two uneven halves. For this island it was not only the first arrival of the Czech crew, but also about the landing of the largest and heaviest aircraft on this island.
Another great achievement similar to crossing the Atlantic on October 8, 2015 was a three-stage flight around the world with the crew of Petr Janocký, Lukáš Novotný and Patrik Sandanus. During the first 7,000 km long stage, the L-410UVP-E20 with OK-JPP registration was also presented at the China International General Aviation Convention, where this type of aircraft was seen for the first time by local lay and professional public. In the second 11,000 km long phase, the crew waited for a transcontinental flight from Asia to North America, which was the longest stage flight ever made around the world. The last third section, 36,000 km long, lasted six weeks.
Twins with american passport
In 1993, work began on a version of the L-410UVP-E20, which would meet all the requirements for US certification under the FAR-23. The main change was the doubling of some linkages in the control system for increased safety, the installation of 580 kW M601F engines with extended life, developed specifically for this variant of the machine and the pressure (bottom) filling of all fuel tanks from one throat controlled remotely from the cockpit. The maximum take-off weight of the aircraft rose to 6,700 kg and many other minor adjustments were made, including, for example, leading edge lighting to control icing, mechanical door closure signaling, or Fairchild data logger.
This variant was designated as the model L-420 and the first prototype flew on 10 November of the same year with the crew of Ing. Miroslav Srnec and Jaromír Novák. In February of the following year, the prototype with the license plate OK-XYA was shown at the Air Show in Singapore, ILA95 in Berlin and a year later also at the air show in Avalon, Australia. This long journey was connected with the presentation in many Asian countries and pilots Stanislav Sklenar and Ing. Svatopluk Vlcek flew nearly 150 flight hours and nearly 50 000 kilometers. This type was unfortunately only produced two pieces, which today serves in Algeria in Africa with the Air Express Algeria.
L-420XXL is a study based on Fedex interest. This is a special cargo version for the transport of cargo up to a total weight of 2,100 kg or three LD3 containers. The proposed modifications only concerned the fuselage elevation and the installation of the left side door optimized for LD3 containers, alternatively with a rear ramp. The cruising speed of the airplane should be 320-360 km / h. Within this project, a subversion of L-420XXL R was created, which respected the original customer’s requirement for the so-called axial way of container loading. Both variants provided for the same correction at the top of the cargo hull, which included 95 mm higher bulkheads with a wider top and a floor complemented by a standard roller conveyor.
The L-420XXL R version was based on the rear container loading style and would require a brand new rear fuselage, fitted with hinged two-part doors on the sides. However, this major design change would require reconstructing the tail tail beam with overall keel and rudder enlargement and an extension of the front fuselage to improve the range of central machine stability. For a cargo of 3 LD3 containers, the aircraft would need even more extensive reconstruction of the primary design and the installation of more powerful propulsion units. For alternative reconstructions of older L-410 aircraft from flighted Russian reserves was sometimes used the designation L-410XXL or L-410XXL R.
The L-510 was the official enterprise project of a luxury pressurized aircraft (Commuter Class) with a Wide-Body fuselage for 19 passengers. The airframe should have an ideal aerodynamically shaped fuselage with smoothly protruding undercarriage gondolas, a larger passenger compartment allowing the installation of three rows of seats side by side and a large trunk. The entire equipment of the machine was designed as a quick-change system, offering maximum adaptability to the current market requirements. It was planned to install a modern dashboard and engines Pratt & Whitney PT6A-65B with an output of 820 kW. Compared to the machine was supposed to have a span of only 16, 7 m and achieve a maximum cruising speed of 526 km / h with a range up to 2000 km.
Its development began before 1989 based on the Soviet requirement for the aircraft, which was then in the foreseeable future to replace hundreds of L-410 and An-28. After the Velvet Revolution, the study was adapted to world market conditions, but designed from the outset under FAR 23. This type was to become a direct and in many cases a luxury competitor for almost all of the then available aircraft of this class, including small fuselage and the need for long runways. The whole project was most likely stopped by lengthy marketing surveys and very costly technology of planned production of aerodynamically better hull and chassis nacelles.
L-610 is a prototype aircraft with pressurized cabin, which was to become a direct successor to the L-410 series and although rumored to revive the study, so far, are still among these missed versions. It was created at the request of a Soviet customer to develop and manufacture a larger machine with similar characteristics to the L-410. The whole concept eventually ended various changes, problems with the development of the new M602 engine and the constant delay of the first take-off of the prototype. You can find out more about this film plane here.
Let L-410 NG
In 2010, the MOSTA project was launched, which addressed a significant modernization of the L-410UVP-E20 using the latest knowledge in the field of aviation technology development and technology. On the basis of these design works was created a completely new aircraft based on the original timeless design Ing. Ladislav Smrčka, who received the designation L-410NG. The ceremonial “Roll-Out” of the prototype with OK-NGA registration took place on July 15, 2015. Its first take-off was on the 29th of the same month with the crew Stanislav Sklenář and Petr Jarocký. Together with them were on board production quality workers Zdeněk Koníček and Michal Sum. This flight also commenced a series of certification flight tests in accordance with the relevant regulations. In 2016, it was first presented to the professional public at the ILA Aerospace Exhibition in Berlin and its next premiere was the very next year, when it was first performed at the Moscow MAKS.
The all-new design of the (so-called wet) wing made it possible to use the entire internal volume as one large fuel tank and substantially increase the range of the aircraft up to 2,500 km. This feature and increased cruising speeds of up to 417 km / h have also been helped by the more powerful 850 HP GE H85-200 engine and the AV 725 propeller. variant L-410UVP-E20. The maximum take-off mass and payload have also improved significantly, allowing 500 kg more to be carried.
In order to increase safety and reduce the load on the crew, the cockpit has undergone an overall upgrade. these were mainly the installation of Garmin 3000 avionics with Glass Cockpit technology and changes in the overall cockpit ergonomics. The company introduced the “Damage Tolerance” philosophy for these aircraft, extending the overall life of the aircraft. After obtaining the EASA certification at the beginning of 2018, serial production was launched and the first piece got into the air on 28 March of the same year. Currently, the type also has two other certificates according to FAA and FATA. The version will be offered in all modifications as its predecessor L-410UVP-E20.
- L-420 XXL
- L-420 XXL R
|Manufacturer||Let Kunovice (now Aircraft Industries a.s.)|
|Capacity||19 passengers or
1 800 kg of cargo
|Engine||2 x Walter M 601E|
|Engine power||2 x 560 kW|
|Wing area||35,18 m²|
|Available||7 000 m|
|Flying range||1 500 km|
|Manufacturer||Let Kunovice (now Aircraft Industries a.s.)|
|Capacity||19 passengers or
2 300 kg of cargo
|Engine||2 x GE H85-200|
|Engine power||2 x 634 kW|
|Wing area||34,86 m²|
|Available||6 100 m|
|Flying range||2 570 km|