In aircraft design, a chine is a longitudinal line of sharp change in the cross-section profile of the fuselage or similar body. The term chine originates in boatbuilding, where it applies to a sharp profile change in the hull of a boat. In a flying boat hull or floatplane float, the longitudinal line of sharp change in cross-section where the bottom plane meets the sidewall is an example of a chine.

The Lockheed A-12 is a retired high-altitude, Mach 3+ reconnaissance aircraft built for the United States Central Intelligence Agency (CIA) by Lockheed's Skunk Works, based on the designs of Clarence "Kelly" Johnson. The aircraft was designated A-12, the 12th in a series of internal design efforts for "Archangel", the aircraft's internal code name. In 1959, it was selected over Convair's FISH and Kingfish designs as the winner of Project GUSTO, and was developed and operated under Project Oxcart.