This XL-29 is the third prototype built and the first that actually flew. The first flight was in April 1959 and in total it accumulated 315 h, 15 min. In 1965 it was handed over to the Antonín Zápotocký Military Academy in Brno as a teaching airframe and in May 1972, the plane was handed over to the Vojenský historický ústav - VHÚ (Military History Institute, the parent organisation of Stará Aerovká, the Kbely museum and many others in the ČR) for preservation.

The third prototype of the L-29 Delfin.