The Frka Tr. I is an outdated design, based on old Sudrian biplanes license-bought several years before the Sudrian Exodus and Ostojican Civil War. Finally put into production in mid-1923, the Tr. 1 utilizes a native Istran-designed light rotary engine to give it its signature fine handling and manoeuverable, though somewhat hard-to-master flight characteristics. The Tr. I above is that flown by Istran Ace Fredrike Aap, nicknamed "The Bumblebee" for his unusual flying style and his Tr. I's bright yellow-and-black livery.
Based on @dairy_king / @merrie_monarch 's biplane, converted into a triplane with modified tail and re-engine'd.