Types and Advantages of Airfoils

DSC_0303In our last segment we discussed what and airfoil is and how it works. If you remember, airfoils have the ability to increase the traction of a vehicle by creating a downforce. The angles of attack can be increased via the implementation of a symmetrical airfoil; the generation of a zero angle of attack is achieved through the use of cambered (asymmetric) airfoils.

Today we’ll explore some of the different types of airfoils, as well as the advantages and uses of each.

The various types of airfoils are as follows:

1. Semi-symmetrical Airfoil:  Most of the full size planes possess this type of airfoil. It has a fully curved top and a half curved bottom and is both thinner and has less drag than its symmetrical counterpart.
2. Symmetrical Airfoil:  Symmetrical airfoils are equally curved on both sides, and are typically quite thick which makes them very strong. This combination of features generates high lifts with changes in power and speed – the altitude of the plane is maintained via changes in speed.
3. Flat Bottom Airfoil:  This type of airfoil is usually seen in trainer flights. The bottom is flat, the top is curved, and they look extremely thin. It should be noted that flat bottoms are speed sensitive. They look extremely thin. Its bottom is flat and top is curved. Flat bottoms are speed sensitive. Power and speed produces great lift with flat bottoms, making them similar to symmetrical airfoils.
4. Supersonic Airfoil: A supersonic airfoil is used to generate lift at supersonic speeds. Its need arises when an aircraft is operated consistently in supersonic range.
5. Supercritical Airfoil: Supercritical airfoils are designed to delay drag in the transonic speed range. They have a flat upper surface, a highly cambered aft, and a greater leading edge radius.

Why all the different types? Because different airfoil shapes create different amounts of drag and lift. For instance, a plane that has been engineered to fly at supersonic speeds will have a different airfoil shape than that of one which has been designed to fly at a much lower speed.  This is due to the fact that the air flows in slightly different ways depending upon the speed and altitude of the aircraft. Typically, airplanes with a low-to-medium speed capacity will possess airfoils with greater thickness and camber to allow for maximum lift.

Another that comes into play is altitude. The density of air is greater at lower altitudes, and more molecules in the air generate a greater amount of lift than fewer molecules in the same amount of air would. Therefore, greater camber is utilized to give lift at slower speeds.

Faster (supersonic) and higher altitudes require a thinner airfoil. This is due to the fact that, when flying at (or close to) the speed of sound, a shock wave forms at the nose of the plane. Researchers at NASA discovered that the incorporation of a thin airfoil delays the shockwave formation, which reduces the drag that the airplane experiences as it moves through the shockwave.

Thanks for visiting us today to learn more about airfoils…we hope to see you back here soon!