Based on the Stanley #113, this compass (aka circular) plane by Kunz is ideal for planing curved surfaces. It adjusts to either concave or convex. Before you turn that big knob up top, you should ease-off the tension screw. You can tighten it down once your arc is set. Plus it's just about the coolest looking plane out there... and would look fabulous on your desk when you're not using it in your shop!
Blade is 1-3/4" wide, bed is 10-1/4" long. Cast iron body, steel sole.