Designing an Aerofoil: Factors, Variables, and Optimization

Designing an aerofoil is a complex process that involves multiple factors and variables. The specific design of an aerofoil can vary significantly based on the aircraft's intended use, such as a crop-duster, fighter plane, or airliner. This article explores the key factors determining aerofoil design, including diagrams and examples.

The Role of Purpose in Aerofoil Design

The design of an aerofoil depends on the specific purpose for which the aircraft was designed. A crop-duster requires a different aerofoil than a fighter plane, which in turn differs from that of an airliner. There are dozens of airfoil sections available, and extensive literature exists on this subject. NASA and its predecessor, NACA, have conducted thousands of wind tunnel tests over the past century and have a vast amount of design data.

Main Variables Influencing Aerofoil Design

Designing an aerofoil involves a complex balance of various variables, including:

Aircraft Size and Weight: Variants of aircraft, such as the Boeing 747 and the F-16 Fighting Falcon, require different aerofoil designs due to their distinct size and weight. Fuel and Payload Weight: The amount of fuel and payload affects the aerofoil's shape and efficiency. Aircraft Material: The choice of material, whether aluminum, composite, or other lightweight materials, influences the aerofoil's design. Top Speed: High-speed aircraft require streamlined aerofoil shapes to reduce drag. Maximum Altitude: High-altitude aircraft have specific aerodynamic requirements for efficient performance at high altitudes. Range: Aerodynamics play a crucial role in determining the range and fuel efficiency of the aircraft. Minimum Landing Speed: The aerofoil must be designed for efficient and safe landing. Type and Number of Power Plants: The design must accommodate the aircraft's propulsion system's characteristics.

NASA and NACA: Wind Tunnel Testing and Data

NASA and NACA have conducted extensive wind tunnel testing on hundreds of airfoil profiles over the past century. Engineers can refer to the vast amount of data they have compiled, which is organized for easy access. An engineer can look up an airfoil profile by number, and decide which profile best fits the application for their design.

Conclusion

The key to designing an aerofoil lies in a thorough understanding of the aircraft's intended use and the multiple variables that influence its design. By leveraging the wealth of data and testing conducted by organizations like NASA and NACA, engineers can optimize aerofoil performance for various applications.