MolaKule Q&A on Aircraft Structures VI WIngs

[Exhaustgases]

This is the Absolute Last Question in this Series:

Wing shapes of airfoils are many and varied to suit the application.

Question: Why are most commercial aircraft wing profiles composed of two or more different NACA airfoils?

https://handwiki.org/wiki/Physics:NACA_airfoil

Efficiency?

 

[barryh]

I would have thought different profiles to ensure efficiency at both cruise and landing speeds.

 

[Cujet]

The different wing profiles are used for multiple reasons. The inboard wing structure often houses the landing gear, provides adequate structure to mount engines, contains the bulk of the fuel and often has a thick airfoil that provides excellent low speed lift. A thinner profile outboard of the engines can help reduce drag, may employ laminar flow profiles and are often configured to reduce shockwave formation.

We also may have configured the wing to control stall characteristics and allow for roll control during a stall.

 

[MolaKule]

The different wing profiles are used for multiple reasons. The inboard wing structure often houses the landing gear, provides adequate structure to mount engines, contains the bulk of the fuel and often has a thick airfoil that provides excellent low speed lift. A thinner profile outboard of the engines can help reduce drag, may employ laminar flow profiles and are often configured to reduce shockwave formation.

We also may have configured the wing to control stall characteristics and allow for roll control during a stall.

All good answers, with Cujet summarizing the main points.

Different wing profiles from the fuselage attachment onward to the wing tip are designed to contend with the various wing loadings encountered, the need for the best Lift-to-Drag ratio at various speeds, and for flight stability.

Depending on the wing design and flight profile(s), there be as many as three different NACA profiles encountered with smooth transitioning from one profile to the next.

An informative wing design review can be found here:

https://www.fzt.haw-hamburg.de/pers/Scholz/HOOU/AircraftDesign_7_WingDesign.pdf