Clara Campoamor' with her photo covering both sides of the plane's fin (vertical stabiliser). The crash prompted a change to a single vertical stabiliser tail design. The fin comprises the fixed vertical stabiliser and rudder. Additionally, lack of a vertical stabiliser allowed for wider field of fire. A rotary wing is typically unstable in yaw, requiring a vertical stabiliser. Instead of a single vertical stabiliser, there were two mounted under the rear wing. A new vertical stabiliser was introduced in 2004 beginning with MSN 555. To compensate for the reduced moment arm, it has a larger vertical stabiliser. Even so-called "tailless aircraft" usually have a tail fin (usually a vertical stabiliser). After he exited the smoke-filled cockpit, Marseille's chest struck the vertical stabiliser of his aircraft. Wasp Major engines, taller vertical stabiliser, hydraulic rudder boost, nose wheel steering, and other improvements.