A further development was the D.III which had balanced ailerons on both wings and a more powerful 230 hp (170 kW) Hiero 6 in-line engine. To improve the problems a modified variant, the D.II was introduced with balanced elevators and balanced ailerons on the upper wings. A prototype was first flown in 1917 and proved to be fast but difficult to handle but because of the urgent need for fighters the D.I entered production. The D.I was a single-seat biplane fighter with improvements over the original Hansa-Brandenburg design which included more efficient wings, a more powerful engine and structural improvements. The Phönix D.I was the second design developed by the Phönix Flugzeug-Werke based on Hansa-Brandenburg D.I design which it has produced under licence. The Phönix D.I, with the D.II and D.III variants, was an Austro-Hungarian First World War biplane fighter built by the Phönix Flugzeug-Werke and based on the Hansa-Brandenburg D.I.
