Aero L-39 Albatros L-39MS

The L-39MS was Aero Vodochody's most ambitious attempt to carry the Albatros forward: an aircraft so thoroughly reworked from the L-39 that it was, in practice, a new design. Development began in the early 1980s, when the L-39, conceived in the sixties to train pilots for third-generation fighters such as the MiG-21 and MiG-23, had reached its limits. From the end of the seventies its users' air forces were taking on fighters of a newer generation, such as the MiG-29 and Su-27, with very different flying qualities and equipment: analogue instruments were giving way to digital ones and cockpits were gaining head-up displays (HUD). The upgrade was also meant to lower operating costs and improve safety and reliability, above all where the troublesome Ivchenko AI-25TL engine was concerned.

Design work was first led by Jan Vlček; after his death in 1984, Vlastimil Havelka took over. The aircraft was initially called the L-39M ("modernisation"), but when it was decided that it would be a light attack aircraft as well as a trainer it became the L-39MS ("modernisation super"). The fundamental change was replacing the AI-25TL with the Lotarev DV-2 turbofan of about 21.6 kN thrust, licence-built by ZVL Považská Bystrica and paired with a Safír 5M auxiliary starting unit. To fit the L-39MS the engine underwent extensive changes, on which the ZMKB Ivchenko-Progress design bureau and ZVL worked together; ZVL, which until then had mostly made motorcycles and small farm machinery, had no experience with jet engines and ran into huge problems with deadlines and build quality.

The airframe was also modified and strengthened. The engine air intakes were changed, the fin was enlarged, and the ailerons and tail surfaces gained hydraulic boosters. The wing was strengthened throughout and the tip tanks grew from 100 to 230 litres; a 15-litre fuel accumulator allowed about 10 seconds of inverted flight, and the fuselage held five rubber bag tanks. The cockpit was slightly enlarged and given a one-piece canopy hinged upwards, along with digital instruments integrated into an entirely new on-board electronic system, with a HUD in both cockpits and one multifunction display. Both crew sat on VS-2A zero-zero ejection seats, and the student was seated lower to improve the instructor's view. For the attack role, a pod with a 23 mm twin-barrel Gryazev-Shipunov GSh-23 cannon and 150 rounds could be carried under the cockpit behind the nose gear; there were four underwing pylons, rated at 500 kg inboard and 250 kg outboard, and the aircraft could also carry R-3 air-to-air missiles. With the DV-2, maximum speed rose to 872 km/h.

The first prototype, X-21 (OK-184), flew on 30 September 1986, still with the original AI-25TL and painted white and blue-grey. The following prototypes, X-22, X-23 and X-24, already had the DV-2; X-23 was used for static ground testing. On 11 September 1992 X-24 (OK-182) crashed near Sojovice during factory aerobatic tests at high load factors, killing test pilot Karel Pánek and technician Jiří Chvojka; a memorial stands at the site.

Delays in engine production and in developing the on-board electronics pushed series production back to the end of the 1980s; the first production aircraft flew on 1 October 1989. Aero expected to sell the aircraft in large numbers to Warsaw Pact countries, as it had with the L-39, but the collapse of the communist regimes in Central and Eastern Europe, the break-up of the USSR and the end of the Pact left prospective customers in economic crisis and broke up the supply chain. In the end only six production L-39MS were built, taken over by the Czechoslovak air force between 1990 and 1992. During the 1990s these aircraft appeared at air shows and air days under the export designation L-59, under which Aero sold derived versions to Egypt and Tunisia.

The six aircraft, numbered 0001 to 0006, were assigned to the 1st Training Air Regiment at Přerov. After Czechoslovakia split, Slovakia took 0002 and 0003 and the Czech Republic kept the other four; such a small fleet, divided between two states, made operation and maintenance complicated and expensive. The Czech aircraft flew with the air force display team, active from 1993 to 1996, and in 1996 the L-39MS performed at four events. In December that year 0001 was damaged beyond repair in a hard landing, and its fuselage became an instructional airframe. In 1998 the Czech aircraft were concentrated at the air force flight test department at Prague-Kbely; in 1999 the remaining three were put into storage, and in 2001 they were withdrawn and sold to the United States, where former 0004 to 0006 were registered N104XX, N105XX and N106XX to Air USA Inc. The two Slovak aircraft were assigned in 1999 to the 1st Training Squadron of the M. R. Štefánik Military Aviation Academy at Košice, and after retirement they too went to the United States, as N9016N and N102XX. On 25 January 2006 former 0004 (N104XX) crashed while landing in snow and low cloud at Ketchikan, Alaska: flying too low, it touched the sea three times, lost engine power and came down on a trailer home; the pilot was killed ejecting and eight people on the ground suffered minor injuries. The NTSB attributed the accident to the pilot's failure to follow approach procedures.