Originally Posted by
Spir4
Why would that be? And doesn't an increase in thickness creates an increase in drag?
If you shear a wing as in above's description, i.e. constant apsect ratio, the wing area remains the same. When lloking at the chord length perpendicular to the leading edge this will be reduced. As the absolute thickness of the profiles remains the same, the relative thickness will increase
Due to the pressure gradient across the z- axis (i.e. in the spanwise direction, perpendicular to Fuselage) the air will be pulled towards the perpendicular axis of the Leading edge close in front of the LE.
There are two effects whose significance varies with the Mach Number.
The Sweep of the leading edge helps from M1 to the point where the Mach cone angle is the same as the sweep. That is where a shock wave emanating from one point of the leading edge will hit a neighbouring section of the LE.
At the same time there is the relative thickness perpendicular to the LE. As this is thicker the Mach induced flow detachment on the upper side will have a steeper angle and occur earlier and thus increase drag.