In early 1917, the Brandenburg D.I had reached the limit of its development. The need for a better design prompted Phönix Flugzeug-Werke to build a fighter which might benefit from the heavier, more powerful engines that were becoming available. This led to the introduction of the Phönix D.I, D.II, D.IIa, and D.III biplane fighters. A small, stocky biplane with a single bay, the D.I climbed poorly and was slower and less maneuverable than its opponents, but it offered good visibility and was well armed. When the structural weakness evidenced in early production models was overcome, the Phönix fighters proved to be sturdy, dependable aircraft and Austro-Hungarian pilots soon found they could dive as fast as they wanted without fear of tearing the wings off the plane.