[2] Attracted by aviation, he started pilot training at the flight school from Chitila together with Lt. Stelian Boiangiu, Slt.

[3][4][5] After getting his license, he participated in the autumn military maneuvers that took place at Pașcani-Roman in September 1911, together with pilots George Valentin Bibescu, Mircea Zorileanu [ro], Gheorghe Negrescu, Nicolae Capșa and Poly Vacas.

[2][1] Once the maneuvers were finished, Protopopescu carried out an air tour, on the Bucharest-Turnu-Severin route, being accompanied by his colleague, Gheorghe Negrescu, with another airplane.

[4][2] In the summer of 1912, while flying on a Farman, Protopopescu took part in experiments related to the use of wireless telegraphy for the navy and aviation, considered by some to be among the first in the world.

Knowing that the aeroplane was piloted by Ștefan Protopopescu, it goes without saying that the flying machine behaved wonderfully in the atmosphere during the experiments.

[7] Pilots such as Vasile Craiu, Marcel Drăgușanu [fr], Egon Nasta, Paul Magâlea and Ion Muntenescu, all awarded with the Order of Michael the Brave, were part of this squadron.

Protopopescu strongly supported the proposal and thus he designed a twin-seat training biplane together with engineers Dumitru Baziliu and Gheorghe Țicău.

[13] However, the Astra factory did not respect the prescriptions of the prototype made at the Aeronautical Arsenal and changed the frame of the wings at its own initiative, and this led to the death of test pilot Ioan Sava [ro].

The prototype passed its tests successfully and although it met the requirements, the factory did not receive orders for serial production.

Although the flight performances and features of the aircraft were comparable with others that were in service with the Romanian Air Force, there were no orders for mass-production.