![]() This is important for design, as an aerofoil can be selected with a camber that gives minimal drag at the cruising C L.Ĭamber not only affects lift, but the distribution of the camber is also critical for our next consideration, Pitching Moment. Looking at figure 3 it can be seen that the minimum drag of the NACA 2415 aerofoil is not noticeably higher than the NACA 0015, but it now occurs when the aerofoil is generating significant lift. The increase also moves the ‘zero lift angle-of-attack’ to a negative value, meaning that a cambered aerofoil produces positive lift even at small negative angles-of-attack.įigure 2 – Lift Coefficient vs Angle-of-Attackįigure 3 – Lift Coefficient vs Drag Coefficient With camber the C L the aerofoil delivers is increased across the whole angle-of-attack range, including an increase in the maximum value. Adding camber to an aerofoil results in a couple of effects as illustrated by the lift vs angle-of-attack and lift vs drag graphs in figures 2 & 3. ![]() The first ‘NACA 0015’ is a symmetrical aerofoil which by definition has no camber, the second ‘NACA 2415’ has exactly the same thickness distribution, but has camber added as indicated by the curved Mean Line. The top part of Figure 1 shows two aerofoils which were tested by NACA in the 1920’s. ![]() Let’s start with maximum lift and minimum drag – If you really want a wing which successfully meets both of these requirements the best thing you can do is add flaps or other high-lift devices, but for the sake of this discussion that would be cheating! So how do we get more lift? The simple answer is to choose an aerofoil profile with some curvature, or ‘camber’ in the technical jargon. There are of course other non-aerodynamic considerations such as providing the section thickness to minimise the structural weight and provide enough storage for fuel, undercarriage etc., or more subtle considerations such as the effect of aerofoil selection on control forces, but meeting the above criteria is a good start!
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