Camber is generally introduced to an airfoil to increase its maximum lift coefficient, which in turn decreases the stall speed of the aircraft. The final design parameter we’ll discuss is camber which is a measure of the asymmetry between the upper and lower surface. Defining the thickness in terms of a percentage allows an airfoil design to be independent of the chord such that a single airfoil profile (shape) can be specified for any wing of a given chord length. This means that the height at the thickest section is equal to 12% of the total chord. The airfoil plotted above has a thickness-to-chord ratio of 12%.
The thickness of the airfoil is a very important design parameter and as always expressed as a percentage of the total chord. This is a convenient way to display an airfoil, as different chords can be normalized and compared directly to one another. In the example shown above, the chord has been normalized such that the leading edge is located at a chord location 0 and the trailing edge at 1.
This often varies down the span of the wing as the wing tapers from the root to the tip. The length of the airfoil from leading to trailing edge is known as the airfoil chord. The airfoil upper and lower surfaces meet at the leading and trailing edges. This is easy to remember if you think of the front of the airfoil as leading its movement through the air. The front of the airfoil is named the leading edge and the rear the trailing edge. Before we do this we’ll start by presenting a few fundamental definitions in order to understand how and why an airfoil is shaped as it is. We are now going to move from looking at the wing in planform and concentrate on the section profile of the airfoil that is used on the wing. We also discussed the aspect ratio and how a longer, thinner wing will reduce the total drag of the wing up to a particular speed whereafter transonic speed effects begin to dominate the total drag produced which necessitating a sweeping of the wing to combat the transonic drag rise. In this post we look more closely at the shape of the wing airfoil: why this differs from aircraft to aircraft, and how a careful airfoil selection will help to produce the flying characteristics you desire for your airplane.Īfter reading the post on wing area and aspect ratio, you should appreciate that there exists a very clear relationship between the size (weight) of the aircraft and the size of the wing (wing area) required to operate the aircraft as intended. Specifically we looked at wing area and aspect ratio. In a previous post we looked at the importance of the shape and plan-form of the wing, and how this has a great impact on the flying characteristics of the aircraft.
#Airfoil diagram series#
This is part 5 in a series of fundamental aircraft design articles that aims to give you an introduction to aircraft design principles.
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