Most aircraft have been designed with planar wings with simple dihedral (or anhedral). Some older aircraft such as the Beriev Be-12 were designed with gull wings bent near the root.[citation needed] Others, such as the Vought F4U Corsair, used an inverted gull wing design, which allowed for shorter landing struts and extra ground clearance for large propellers and external payloads, such as external fuel tanks or bombs. Modern polyhedral wing designs generally bend upwards near the wingtips (also known as tip dihedral), increasing dihedral effect without increasing the angle the wings meet at the root, which may be restricted to meet other design criteria.