Delta refers to a type of wing shape that is triangular in planform, with the leading edge forming a straight line and the trailing edge forming a right angle. This wing shape is characterized by its high lift to-drag ratio and is often used on aircraft that are designed to fly at high speeds, such as military jets and supersonic aircraft.
The delta wing shape is created by attaching a triangular wing to the fuselage at a high angle of attack, with the leading edge at the top and the trailing edge at the bottom. This creates a large amount of lift at high speeds, making it well-suited for high-speed flight. However, delta wings can also be less efficient at lower speeds and may require a higher angle of attack to generate enough lift, which can cause instability.
Delta wings are also sometimes used on space vehicles, such as the Space Shuttle, to provide lift during atmospheric reentry. The delta shape helps to create a large amount of lift while also generating a lot of drag, which slows the vehicle down as it reenters the Earth's atmosphere.