The 1910 Penkala Biplane also called the Leptir () was the first aircraft to fly in Croatia.
The Leptir was a single engine, sesquiplane aircraft with conventional landing gear. The open girder fuselage provides an unusually long distance to the tail surfaces, compared to modern aircraft. The flat bottom surface of the fuselage was covered, forming a long thin triangular surface intended to provide lift, which was not functional in level flight. The aircraft was tail heavy with a center of gravity at 70 percent of wing chord.
The first flight occurred on 22 June 1910 with pilot Dragutin Novak. The aircraft was crashed several months later.