# Is the sweep angle of an inverted wing zero degrees?

Is the sweep angle of an inverted wing zero degrees, when the angle between the fuselage and the inverted delta wing is 90 degrees? Or is it different because the span of the wing isn't constant over the chord.

• The term 'inverted' is normally connected to flying upside down. It would help if you add a sketch - I guess you mean a delta wing with the tip pointing aft. – Peter Kämpf Nov 15 '14 at 21:12

Such a wing has a negative sweep angle. If you take the weighed average of leading ($\varphi_{le}$) and trailing edge sweep angle ($\varphi_{te}$), you get the quarter chord sweep angle ($\varphi_{25}$): $$\varphi_{25} = \frac{\varphi_{te} + 3\cdot\varphi_{le}}{4}$$