Jay Honeck writes:

The Ercoupe is incredibly easy to fly -- it was designed by Fred Weick (the
guy who later designed the Cherokee) to be "Everyman's Plane", the plane
that anyone can fly with minimal training after they come back from WWII.

To achieve this he made it as automotive as possible, with the yoke working
as a steering wheel on the ground, and the rudder pedals eliminated
completely. (The rudders are interconnected with the ailerons, and work
remarkably well at keeping the ball centered.)

So why didn't it catch on? In _Stick and Rudder_ Wolfgang regularly sings its
praises, without actually naming it.