Airplane design is an ever-evolving struggle between controllability and stability. In an F-16 fighter jet, controllability is far more important than it is in our Cessnas, where stability is the main goal. One of the best tools to help an engineer introduce stability about the roll axis is dihedral.
Dihedral is just a fancy way of describing the angle of the fuselage relative to the angle the wings are attached to it. This angle has a direct impact on the dihedral effect, or the ability of an airplane to right itself. It’s not something the pilot can adjust. Rather, it’s an angle the engineers have decided on that allows for the best tradeoff between stability and controllability.
The dihedral effect is easy to understand when you think of an airplane in a bank. Imagine you are flying a left turn. Because both wings are bolted onto the fuselage at an angle, the left wing will have a higher angle of attack than the right wing. And as a result it will be producing more lift. This lift will cause the wing to rise (depending on the bank angle), and usually right the airplane if no other input has been given.
The next time you’re on the ramp, look at all the different aircraft and the amount of dihedral on each. You'll see that different manufacturers take different approaches to the problem of stability.
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