- All single seat (S1n) and two seat (S2n) are high performance biplanes with variations of a design that started in 1944. The design was popularized by Betty Skelton, Caro Bayley, and other performers, which lead to the offering of plans around 1960.
- S-1C = Plans built aircraft, flat bottom wing, two aileron, single seat engine was normally anything from an 62.5 kW continental to a 132 kW Lycoming, fixed pitch prop.
- S-1D = Just an S-1C but with 4 ailerons.
- S-1E Like S1-S, but homebuilt (E for Experimental) symmetrical wing.
- S-1S = 132 – 147+ kW, single seat, factory or homebuilt, symmetrical wing, 4 ailerons, fixed pitch prop.
- S-1T = 147 kW Lycoming AEIO-360, 4 aileron, single seat, factory built, symmetrical wing, constant speed 2 blade Hartzell prop.
- S-1-11B = 220+ kW Lycoming, 4 aileron, single seat, experimental-plans or factory built and factory component parts, symmetric airfoil, 3 blade constant speed prop rolls better than 400 degree/s, climbs better than 1.220 m/min.
- S-2A = 147 kW Lycoming, 4 aileron, 2 seat, factory built, symmetrical airfoil, constant speed 2 blade Hartzell prop.
- S-2B = 191 kW Lycoming, 4 aileron, 2 seat (larger fuselage than S2-A), factory built, symmetric airfoil, constant speed 2 blade Hartzell prop with options for a 3 blade MT or 3 blade Hartzell composite prop.
- S-2C = 191 kW Lycoming, 4 aileron, 2 seat, factory built, symmetric airfoil, constant speed 3 blade prop , current production model. Improved version of S-2B, with improved ailerons and rudder.
- S-2E = basically a kit built S-2A (maybe a few plans built).
- S-2S = 191 kW Lycoming IO540, 4 aileron, single seat, factory built, symmetrical wing, constant speed prop, 2 blade Hartzell prop…derivative of the S-2A, factory built, often used by airshow performers such as Jim LeRoy of Bulldog Airshows.
- Model 12 – 264 kW M14P Russian radial engine, 2-blade or 3 blade MT propeller, plans built, component parts available. Developed by Jim Kimball Enterprises in Florida.
- Model 13 – a “coupe” type monoplane design. It was never built.
- Model 14 – A new design being built by Steen Aero Lab Two-place, 294 kW M14.
- Model 15 – Reported as a light sport type monoplane aircraft being developed by Steen Aero Lab.