Does stall angle of attack in inverted flight change due to the camber of an asymmetric airfoil? What is the stall angle in an inverted flight configuration? How does it relate to the stall angle in normal flight?


As visible in the image below, in upright flight the lower pressure is on the extrados of the wing. In inverted flight the lower pressure is on the intrados.


(source)

The air stream separation at the stall will occur on a side with different characteristics. One could expect the stall will happen differently.


Equivalent representation, where the gravity is inverted and the wing orientation remains in the same direction. Flying inverted implies flying at a negative angle of attack.



The values taken into account are the airflow direction and the chord line, reflected in the angle of attack value.


As commented, while the two previous images suggest a wing in horizontal flight, the situation can be extrapolated to any stable linear trajectory with a negative AoA. 



The horizontal plan or the pitch angle are not necessary to determine the stall angle (though they influence the stall speed).
Short answer: Asymmetric airfoils have different positive and negative stall angles, the largest absolute value of the two depends on factors like nose shape and camber. With positive camber (normal and utility aircraft), the negative stall angle can be the largest (in absolute values) but the maximum negative lift available before stall will be smaller than for the positive stall. Larger Reynolds numbers push the stall further away in both directions

It depends on the airfoil. With symmetric airfoils, the stall angle is the same for positive and negative stalls. Positively cambered airfoils (the sort mostly used) have their negative stall at a smaller absolute value of the lift coefficient compared to their positive stall, but the stall angle can well be at a higher absolute value.

Below you see a polar plot for a supercritical airfoil which I used for this answer. The positive stall angle of attack is 8°, while the negative one is around -10°.



Polar plot of the R2A airfoil at Mach 0.6 (own work)

The stall angle depends on details of the nose contour and the camber: Positive camber means that the zero lift angle is shifted to negative values, so there is some bias to negative values in the polar. However, if the lower part of the nose has very high curvature, it will create a high suction peak which leads to flow separation just aft of the nose already at a small negative angle of attack.

One extreme case would be the Göttingen 417a airfoil. Airfoiltools unfortunately plots only a range of Reynolds numbers suitable for model airplane enthusiasts, but the plot below should get the point across. The positive stall angle is 12° at the highest Reynolds number, while the negative stall angle is only around -8°.



Gö 417 lift over angle of attack. The lowest Reynolds number (blue line) is 50,000 and the highest is 1,000,000 (olive green line). Note that all curves are XFOIL predictions - real-world data might look differently.