The L-39 was developed in the Aero works at Vodochody by a team led by
the chief designer, DipI. Ing. Jan Vlcek. Two prototype airframes had
been completed by November 4, 1968 when the no. 02 aircraft flew for the
first time, piloted by Rudolf Duchon. The no. 01 airframe was utilized for
structural testing. By the end of 1970, five flying prototypes and two
for ground testing had been completed. Slightly larger and longer air
intake trunks were fitted after preliminary flight tests.
The fourth prototype has been flown with underwing rocket pods and
air-to-air missiles, to evaluate the L-39 as a light ground attack
aircraft and this version is reported to have been ordered by Iraq in
addition to the standard L-39 trainer.
A pre-production batch of 10 aircraft began to join the flight test
programme in 1971, and series production started late in 1972,
following official selection of the L-39 to succeed the L-29 as the
standard jet trainer of all Warsaw Treaty countries except Poland.
Service acceptance trials, in Czechoslovakia and the USSR, took place
in 1973, and by the Spring of 1974 the L-39 had begun to enter service
with the Czech AF.