Welcome back to our Word of the Week!

Every week, we look together at a word that is either interesting, funny or mysterious and that appeals to all of us in the aviation community.

This week, we again feel generous, so we are going to go with 2 words of the week 🙂

Dihedral / Anhedral

Dihedral: the upward inclination of an aircraft wing in relation to the lateral axis.

Anhedral: the downward inclination of an aircraft wing in relation to the lateral axis

You understood it already, these two words have something to do with the angle formed by the wing and the horizontal plane.

When the wingtip is higher than the root (where the wings connects to the fuselage), we talk about dihedral.

A very clear dihedral on a Boeing 737-800

On the contrary, when the tip is lower than the root, it is known as anhedral.

The dihedral angle has a strong influence on dihedral effect, which is named after it. Dihedral effect is the amount of roll moment produced in proportion to the amount of sideslip. Dihedral effect is a critical factor in the stability of an aircraft about the roll axis (the spiral mode). It’s also pertinent to the nature of an aircraft’s Dutch roll oscillation and to manoeuvrability about the roll axis. For example, high-wing aircraft, which are more stable by nature because of the pendulum effect usually have a very shallow dihedral angle, or even an anhedral to increase manoeuvrability, by decreasing stability.

The remarkable anhedral angle on the British Aerospace 146

Have a nice week, and see you next Wednesday for a new word of the week!