 Most jet fighters of the period used a swept-wing or delta-wing, which provided a reasonable balance between aerodynamic performance, lift, and internal space for fuel and equipment.The Lockheed tests, however, determined that the most efficient shape for high-speed supersonic flight was a very small and thin, straight, mid-mounted, trapezoidal wing.Much of the data on the wing shape was derived from testing done with the experimental unmanned Lockheed X-7, which used a similar-shaped wing.