A personal or unit emblem on aircraft?

[Theodor]

For sure the aircraft, prepared to be delivered to Bulgaria, but destroyed in the German attack, are a rare subject, but this is well known story and there are decades old articles on the theme, nothing unseen and nothing sensational. There were also a few Bulgarian student-pilots trapped in the conflict, they fled right infront of the advancing Germans, not to be caught in the combat, and by mistake two took the wrong train and ended up in... the USSR! Arrested for a few days, fortunately soon were released. But that's a different story. The real highly unusual and interesting were the white "Bravery cross"emblems. Still a mystery?!