page_title: Cruciform wing
section_title: Variable geometries
hierarchical_section_title: Cruciform wing / Other proposed applications / Variable geometries
context_page_description: A cruciform wing is a set of four individual wings arranged in the shape of a cross. The cross may take either of two forms; the wings may be equally spaced around the cross-section of the fuselage, lying in two planes at right angles, as on a typical missile, or they may lie together in a single horizontal plane about a vertical axis, as in the cruciform rotor wing or X-wing.
context_section_description: Shortly after World War Two, the French company Matra began studies of a variable-geometry aircraft in which two sets of wings were provided, one for low-speed takeoff and landing, and the other for high-speed flight. Long-span wings for low speed flight were set at right angles to short-span wings for high-speed flight. One set lay horizontal for use as the lifting wings, while the other was set vertical. The supporting fuselage section could be rotated 90° to swap them over, and the unused set of wings could be folded backwards and partially or wholly retracted into the fuselage. It was patented by Matra's chief designer, Robert Roger, in 1946.
  The bi-directional wing is a similar approach to the same problem. It comprises a long-span low speed wing and a short-span high speed wing joined in the form of an unequal cross. The craft would take off and land with the low-speed wing across the airflow, then rotate it a quarter-turn so that the high-speed wing faces the airflow for supersonic travel. It has been studied in the form of a bi-directional flying wing.
caption: Bi-directional flying wing, plan view