[2] In response to a sizable requirement for a common jet-propelled trainer to be adopted across the diverse nations of the Eastern Bloc, Aero decided to embark upon their own design project with a view to suitably satisfying this demand.

During the early 1970s, the type was succeeded in the principal trainer role by another Aero-built aircraft, the L-39 Albatros, heavily contributing to a decline in demand for the earlier L-29 and the end of its production during 1974.

[1] Their work was centered upon the desire to produce a single design that would be suitable performing both basic and advanced levels of the training regime, carrying pilots straight through to being prepared to operate frontline combat aircraft.

Accordingly, both simplicity and ruggedness were stressed in the development process, leading to the adoption of manual flight controls, large flaps, and the incorporation of perforated airbrakes positioned on the fuselage sides.

During 1961, a small pre-production batch of L-29s were evaluated against the Polish PZL TS-11 Iskra and the Russian Yakovlev Yak-30, the main rival submissions for the Warsaw Pact's standardised trainer.

Shortly after the completion of the fly-offs, it was announced that the L-29 had been selected as the winner; according to aviation author John C. Fredrikson, this outcome had been highly unexpected and surprising to several observers.

[1] Regardless of the result, Poland chose to continue to pursue the development and procurement of the TS-11; however, all of the other Warsaw Pact countries decided to adopt the Delfín under the agreements of COMECON.

Another model, an armed reconnaissance version complete with multiple downwards-looking cameras installed in the rear cockpit position, referred to as the L-29R, was also under development; however, during 1965, the L-29R project was terminated.

"[4] In the trainer role, the L-29 enabled air forces to adopt an "all-through" training regime using only jet-powered aircraft, entirely replacing earlier piston-engined types.

For this latter mission, they were equipped with hardpoints to carry gunpods, bombs or rockets; according to Fredrikson, the L-29 functioned as a relatively good ground-attack aircraft when deployed as such.

[1] On 16 July 1975, a Czechoslovak Air Force L-29 reportedly shot down a Polish civilian biplane piloted by Dionizy Bielański, who had been attempting to defect to the West.

Both L-29s consistently posted laps at or above 500 miles per hour; former Astronaut Curt Brown took first place in "Viper," followed by Red Bull racer Mike Mangold in "Euroburner.