How the stall develops on a Coupe

Credit goes to Stan Thomas and his book The Ercoupe.  Please, someone, get rights to this book and re-publish it!

The airflow of a low wing aircraft is expected to start to burble at the junction of the wing and fuselage.

By choosing the filet between them, Fred was able to control and design the shape of the stalled air over the wing.  The stall starts at the rear of the wing and moves forward/outward as the plane slows.

The outer part of the wing never stalls. 

1.  Due to the center section's firm stall, the spanwise lift breaks down and the outer panels act as short, low aspect ratio wings.  Because of this, the outer panels can go to a higher angle of attack than they could otherwise.

2.  The pitching moment of the main wing changes as the center portion stalls, tending to reduce the angle of attack.

3.  The burbling, turbulent airflow from the stalled wing root then passes over the tail giving a bouncy, turbulent sensation as a stall warning.  And the turbulent flow over the empennage also disrupts the downwash from the wings and reduces the elevator's attempt to push down the tail, limiting the amount of stall possible.

In essence, the burbling of the stalled airflow from the wing and passing over the tail is the stall warning on Coupes.  But, more importantly, these design features are responsible for the aircraft's certified characteristic inability to maintain a spin.