Wing sweepback also increases dihedral effect. This is one reason for anhedral configuration on aircraft with high sweep angle, as well as on some airliners, even on low-wing aircraft such as the Tu-134 and Tu-154, with the small German 1930s – 1945 biplanes of the Bücker Flugzeugbau, the Bucker Jungmann two-seat trainer and more famous Bücker Jungmeister aerobatic competition biplane, both having approximately 11° of wing sweepback giving both designs a degree of dihedral effect, beyond the small amount of dihedral both biplanes' designs also featured.