Why Do Aircraft Use Airfoils?

Aircraft wings are designed in specific shapes to achieve the greatest amount of lift possible. Alongside propulsion, lift is one of the major acting forces that enable aircraft to travel from one point to another. While propulsion is generated by an aircraft’s engine(s), lift is produced by the wings and body. In order to effectively generate lift, wings have an airfoil shape, Usually called airfoils for short, these flight surfaces obtain lift from the air through which they move.

How To Achieve Leveled Flight

Due to their shape, airfoils can minimize the energy required to maintain the aircraft in the air. To do this, the design of the airfoil is critical. The top surface of the wing profile has a greater curvature than the lower surface of the aircraft, and the difference in curvature is what allows the wing to build up the lift force. Essentially, air flowing over the top surface of the wing must reach the trailing edge of the wing in the same amount of time as the air making its way under the wing.

However, the air moving over the top surface travels at a greater velocity than the air passing below the wing because it has a greater distance to cover. This increased velocity means that there is a corresponding decrease in pressure on the surface; thus, the resulting pressure differential forces the wing upward in the direction of the lower pressure. Keep in mind that lift can be increased by increasing the AOA (angle of attack), wing area, velocity, air density, or simply changing the shape of the airfoil. Once the force lift on the wing equals the force of gravity, the aircraft can keep level flight.

Airfoil Properties That Make Flight Possible

The individual sections of an airfoil are unique when compared to those of the wing or aircraft as a whole. This is because of the effect of the wing outline. The wing has many airfoil sections, from root to tip, with taper, twist, and sweepback variations, and the aerodynamic properties that each section offers are determined by the action of each section along the span.

It is worth noting that the shape of the airfoil is indicative of the amount of turbulence or skin friction it will produce, consequently affecting the wings efficiency. Turbulence and skin friction are mainly controlled by the fineness ratio, which is the ratio of the chord line of the airfoil to the maximum thickness. For instance, if the wing has a high fineness ratio, it produces a large amount of skin friction. In contrast, if a wing has a low fineness ratio, it produces a large amount of turbulence.

Generally, the efficiency of a wing is determined by the lift to drag ratio (L/D), which varies with the AOA and also reaches a definite maximum value for a specific AOA. At this angle, the wing has reached its maximum efficiency. Meanwhile, the airfoil shape determines the AOA at which the wing is most efficient. Extensive research has demonstrated that the most efficient airfoils have the maximum thickness located about of the way back from the leading edge of the wing.

The amount of lift produced by an airfoil increases with an increase in wing camber. Camber is defined as the curvature of an airfoil above and below the chord line surface. For further context, upper camber refers to the upper surface, lower camber refers to the lower surface, and mean camber refers to the mean line of the section. Moreover, camber is positive if departure from the chord line is outward, and it is negative when it is inward.

Wrapping Up

It is clear that airfoils are more complex than they appear. Today, an airfoil has to strike a perfect medium between all the aforementioned extremes. This is especially true because modern aircraft vary according to their intended purpose. If you find yourself in need of top-quality aircraft parts and components, rely on Industrials 3Sixty. Industrials 3Sixty is a leading supplier of aircraft airfoils as well as countless other items that have been sourced from trusted global manufacturers on our Approved Vendor List (AVL). Get started with a competitive quote on any featured item(s) and see how Industrials 3Sixty can serve as your strategic sourcing partner!