1925 saw the Potez XVII, Bristol Lucifer and Macchi 2000/18 flying boat boosting the country's aircraft inventory. The Bulgarian government invited a group of German aircraft engineers, headed by the constructor Herr Hermann Winter to help establish an aviation factory. Named The State's Aeroconstruction Atelliér or Darzhavna Aeroplanna Rabotilnitsa (DAR) the factory was initially managed by the first Bulgarian pilot to achieve an aerial victory – Mr. Marko Parvanov. The first aircraft types produced at the plant were the U-1 or "Uzounov-1" (an indigenous variant of the wartime German DFW C.V) and the DAR 2 (an indigenous variant of the German Albatros C.III of the same era). Both types became well-known and loved by the personnel of the former Air Troops and gained Bulgarian combat service experience. Development of a new type – the DAR 1 – was also started.