09/30/2012. Remarks by Walter van Tilborg: "This original homebuilt biplane was a design of John D. Hatz of Merril, Wisconsin, USA, who also built the first example with an 85 hp Continental C85 engine. Named Happiness this aircraft first flew on April 19, 1968, after work had started in September 1959. The prototype was later re-engined with an 150 hp Lycoming O-320.
The two-seat design was adopted for amateur construction for engines in the 100-160 hp range and plans were initially marketed via Merril Airways and later via Dudley R. Kelly. The first two plans-built aircraft used an 100 hp Continental O-200-A engine with the first example flying in June 1975. Several dozen CB-1s were built and at least one aircraft received a pre-war 90 hp LeBlond radial engine, while the aircraft built by Lorin Wilkinson was powered by an 170 hp Walter/LOM M332A in-line engine.
The developed Hatz Classic model was stressed for more powerful engines and was initially marketed via Makelan Corporation. This variant was designed for the 150-160 hp Lycoming O-320 engine and had slightly different dimensions.
After the death of Dudley R. Kelly, the marketing of the Hatz CB-1 and the Classic was in 1999 taken over by the American Hatz Association and the plans were still available in 2012 from the renamed Hatz Biplane Association. In all over 100 aircraft were built worldwide, including at least one on amphibious floats. The pictured aircraft built by Randy Brooks in 1996. It was registered as Bratz CB-1 (an acronym for Brooks Hatz).