Czechoslovakia has never been a great aviation power, but membership in the Council for Mutual Economic Assistance (CMEA) and the Warsaw Pact Organization (OVD) put this country in the 60-80s as a leader in the production of training aircraft. There is no doubt that light jet aircraft of this class could have been created and produced in the Soviet Union, but the Soviet aviation industry, unlike the present times, was already overloaded with orders, and there was a serious need to support and develop the aviation industry of the countries of the socialist camp.
For a long time, the MiG-15UTI was the main jet trainer of the USSR Air Force. This machine was produced in large series and was used in the Soviet Air Force and DOSAAF until the early 80s. However, in terms of efficiency, avionics composition and flight safety, it did not fully meet the requirements of initial flight training. The Czechoslovak L-29 Delfin, created in 1956, was declared the winner of the competition for a jet trainer for the ATS countries. The competition was also attended by the Polish PZL TS-11 Iskra and the Soviet Yak-30. This decision was largely due to political reasons: representatives of the USSR Air Force believed that the Yakovlev design bureau was better and had greater potential for further improvement. As a result, Soviet pilots were trained on the L-29 Delfin, and the Poles preferred their own TS-11 Iskra trainer. After Dolphin won the competition, the creation and construction of the TCB became among the CMEA member countries the prerogative of the Czechoslovak Socialist Republic (Czechoslovakia).
The Dolphin, being very simple to fly and unpretentious in maintenance, marked a new era in pilot training and quickly fell in love with aviators. At the same time, the aircraft had a number of shortcomings, and attempts to eliminate them demonstrated that the L-29 had very few reserves for modernization. In addition, the improvement of combat aviation put forward new requirements for the training of young pilots. Thus, there was a need for a new TCB.
The technical task for the new jet trainer was formed by the USSR Ministry of Defense, but the official customer was the Czechoslovak Ministry of National Defense (MHO). In particular, it was required, while maintaining the advantages of the L-29, to provide a greater thrust-to-weight ratio and reliability, and to reduce the preparation time for flight. It was indicated that the maximum flight speed could be no more than 700 km / h. The cockpits of the instructor and cadet, in terms of their layout and composition of instruments, were obliged to be as close as possible to the cockpit of a modern fighter. The empty weight of the aircraft was limited to 3400 kg. The new aircraft was supposed to be used in schools for all types of flight training, including the initial one.
Aero Vodochody, a national enterprise, was entrusted with the creation of a new TCB. This Czechoslovak aircraft plant was built in 1953 near the village of Vodohody, 20 km north of Prague. Since then, there has been a serial production of jet aircraft, both Soviet licensed and created in Czechoslovakia. The assembly of the MiG-15, MiG-19S, MiG-21F-13 and the L-29 training aircraft was carried out there.
Initially, the aircraft, designated L-39 Albatros, provided for the use of two engines, which was preferable from the point of view of reliability. But on the other hand, this would inevitably increase the mass, the cost of the aircraft, the preparation time for departure and the fuel consumption. As a result, the customer was convinced of the sufficiency of one engine, especially since the degree of reliability of the new turbojet engines was already very high. After comparative tests of the Czechoslovak M-720 with a thrust of up to 2500 kgf and the AI-25TL bypass engine with a thrust of 1720 kgf, created at the Progress ZMKB under the leadership of A. G. Ivchenko, the choice was made in favor of the second option. It was not the pressure of the Soviet side: the M-720 was too big for a light trainer, and besides, after bench tests, it became clear that its fine-tuning would not be completed quickly. It was assumed that the Prague company "Motorlet" would be engaged in the production of engines, but as a result, the AI-25TL for "Albatross" began to be built in Zaporozhye.
After factory tests in Czechoslovakia in May 1973, state tests began in the USSR. The Soviet pilots had a favorable opinion of the aircraft. They noted that, in general, the L-39 meets the requirements for a single jet trainer aircraft designed to train pilots at all stages. Among the positive qualities of the aircraft, special attention was paid to the proximity of the working conditions in the cockpits of the instructor and the trainee to the cockpits of combat vehicles, excellent visibility from both workplaces, a good rescue system, the ability to start the engine without the help of ground devices, as well as training in the basics of combat use. With the flaps retracted, the landing approach was similar to the MiG-21. The aircraft possessed good aerobatic qualities, allowing it to perform the entire range of aerobatics.
In addition to the advantages, a number of disadvantages were noted: a shorter flight range than a given flight range, an increased landing speed and run length. We were not fully satisfied with the characteristics of the aircraft for withdrawing from a spin, which subsequently required modifications to the nose and vertical tail. The power plant turned out to be the weakest point of the aircraft. Due to problems with gas-dynamic stability, reaching high angles of attack threatened to surge and overheat the turbine. The AI-25TL engine has a low throttle response, it reaches its maximum speed in 9-12 seconds. The pilot actually could not count on a rapid increase in thrust when maneuvering and landing, difficulties arose also when working out the group flight. Despite the identified shortcomings, "Albatross" was recommended for adoption by the USSR Air Force to equip flight schools with it.
The mass production of L-39 at the Aero-Vodokhody enterprise began in 1974. In the USSR Air Force, the first L-39C aircraft began to operate in 1975 at the 105th UAP of the Chernigov Higher Military Aviation School of Pilots. The aircraft surpassed its predecessor L-29 in many ways and quickly won the sympathy of pilots and technicians. The new TCB was distinguished by an excellent view from the workplace, a good air conditioning system, and good ergonomics.
Flight characteristics of the aircraft L-39С
But at the same time, the decision to use the Albatross as an aircraft for initial flight training can hardly be considered fully justified. For a cadet with absolutely no initial flying skills, the L-39 was too strict and fast. The cadets were trusted to perform the first independent flight after 35-40 export flights, and some needed much more. However, the flights were short, and the export program, as a rule, did not exceed 20 hours. When practicing the landing, many novice pilots experienced difficulties due to the change in the nature of the aircraft's controllability at low speeds. On cruising, the car quickly reacted to deflections of the handle and pedals, then it became sluggish on landing. Landing errors were common: high alignment, flights, goats, but the Albatross had a sufficient margin of safety and, as a rule, everything ended well.
To practice the skills of using weapons, the aircraft was equipped with an ASP-ZNMU-39 aviation rifle sight (in the front cockpit), an FKP-2-2 photocontrol device, two simulators controlled by I-318 on the APU-13M1 launchers, two wing beam holders L39M-317 or L39M-118, on which it was possible to suspend air bombs weighing 50-100 kg or NAR UB-16-57 blocks.
The training program provided for a cadet to receive a flight time of 100-120 hours. In addition to mastering takeoff and landing, it included en-route and instrument flights under the curtain, mastering elements of combat use. Future fighters were required to be trained in the basics of intercepting air targets on guidance from the ground. Air combat techniques were practiced with aiming at an optical sight and target acquisition with the homing heads of the R-ZU training missiles. Cadets of all schools practiced "work on the ground" using 57-mm NAR S-5 and 50-kg training bombs.
Very quickly, the L-39C trainer aircraft became one of the most massive aircraft in the USSR Air Force. The plane became “Russified” and was not perceived as foreign. The Latin letter "L" in the designation was immediately replaced by the Russian "L". The letter "C" indicating the modification disappeared altogether, since only one modification was used in the USSR. And his own name "Albatross" was practically not used much more often the slang nickname "Elka". The aircraft entered the majority of flight schools: Kachinskoe, Chernigovskoe, Kharkovskoe, Armavirskoe, Barnaul, Yeisk, Borisoglebskoe, Tambovskoe, Krasnodarskoe. These schools trained pilots for front-line fighter aviation regiments and air defense forces, fighter-bomber and front-line bomber aviation. The strength of the training regiments was much higher than the combat regiments, and in some of them the number of "Albatrosses" exceeded a hundred.
Training L-39Cs were also available in the Centers for Combat Training and Flight Personnel Retraining, in a separate training and test regiment of the USSR Cosmonaut Training Center, in the units of the Air Force Research Institute. A small number of Elok were donated to DOSAAF flying clubs and training centers. Outside the security structures "Elkami" had LII MAP (near Moscow Zhukovsky); they were in the Test Pilot School. Albatrosses were used as flying laboratories and escort aircraft for testing new aviation technology.
The L-39 aircraft became one of the most widespread jet trainers, occupying an honorable fourth place in the number of vehicles produced after the American T-33, the Soviet MiG-15UTI and the L-29 Delfin. In total, more than 2,950 production vehicles were built. The most massive modification was the L-39C, replicated in the amount of 2280 units. Of these, the USSR received 2,080 aircraft. In addition to the USSR, the L-39C trainer was in the air forces of Afghanistan, Vietnam, Cuba and Czechoslovakia. On the basis of the L-39C, the L-39V target towing vehicle was produced in a small series, but this modification was not supplied to the USSR. In the Soviet Air Force, the Il-28 bomber was used to tow air targets from the mid-50s.
Despite the fact that the "Albatross" was developed as a training aircraft, it had a certain strike potential. Of course, such a use case for the USSR Air Force was irrelevant, but many Third World countries, which did not have a large and modern aircraft fleet, seriously considered the TCB as light attack aircraft. Moreover, the L-29 already had such an experience. During the Yom Kippur War in 1973, after a breakthrough of Israeli mobile units through the Suez Canal, unexpected for the Arabs, the Egyptians were forced to throw training aircraft equipped with NAR and free-fall bombs into battle.
In 1975, a version of the L-39ZO aircraft (Zbrojni - armed) was created, with a reinforced wing and four external hardpoints. The creation of a variant with enhanced strike capabilities began at the request of Libya. In the 1980s, this machine was supplied to the GDR (52 aircraft), Iraq (81 aircraft), Libya (181 aircraft) and Syria (55 aircraft). Serial production of this model ended in 1985. A year later, a modification of the light two-seater attack aircraft and reconnaissance aircraft L-39ZA appeared, which was a further development of the L-39ZO aircraft. The vehicle had four underwing and one ventral suspension assembly, as well as a reinforced wing and chassis structure. The mass of the combat load at five nodes is 1100 kg. In addition to NAR and free-fall bombs, a 23-mm GSh-23L cannon with 150 rounds of ammunition is suspended under the fuselage. For self-defense from enemy fighters and fighting helicopters, it is possible to suspend two K-13 or R-60 air combat missiles.
The L-39ZO aircraft received the Air Forces of Algeria (32), Bulgaria (36), Czechoslovakia (31), Nigeria (24), Romania (32), Syria (44) and Thailand (28). A variant of the L-39ZA aircraft with western avionics (in particular, with an indicator on the windshield and a digital processor of the weapon control system) received the designation L-39ZA / MP. Production of the L-39ZA ended in 1994. In the same 1994, the L-39ZA / ART appeared with the avionics of the Israeli company "Elbit", this version was specially developed for the Thai Air Force. In total, in addition to the most massive modification of the L-39C, 516 Albatrosses were built with enhanced strike capabilities. "Elki" were in service with the Air Force in more than 30 countries around the world. And by no means all of them ended up in a legal way: used planes from Eastern Europe and the republics of the former USSR often through "third hands" ended up in countries with unresolved territorial disagreements with neighbors or internal ethnopolitical conflicts in a roundabout way.
