It features a strut-braced high-wing, a two-seats-in-side-by-side configuration enclosed cockpit, fixed tricycle landing gear or conventional landing gear and a single engine in tractor configuration.

The R-120 is structurally strengthened over the R-80 to allow a higher gross weight and accept larger engines.

The non-tapered planform wings have 6061-T6 ribs and spars and employ a NACA 4413 (mod) airfoil.

The airfoil modification removes the undercamber on the bottom of the wing, which makes construction easier, without giving up low speed performance.

6061-T6 is predominantly used for its lower cost and also its better corrosion resistance, since many R-120s are flown on floats.