# What is the meaning of flap detent names (e.g., 10 degrees)?

When I extend my flaps to 10 degrees, what exactly is the 10 degrees measuring? Is this referring to the angle of the flap blades themselves, the new angle of the wing chord, the change in the new critical angle of attack or something else?

• Selecting the first and/or second detent of flap extension may also extend leading edge devices. Also, in addition to 'lowering' the flaps, it may extend them aft of their retracted position. – Terry Jan 21 '14 at 3:20

• @Qantas94Heavy The aircraft's maintenance manual will specify the actual travel (and specify how it is to be measured) though if it's a plain flap and an angular measurement the "where" doesn't really matter - the angle doesn't change, you're just using a different-sized protractor to measure it... – voretaq7 Jan 21 '14 at 17:00