01/15/2019. Remarks by Walter van Tilborg: "The WA.51/WA.54 four-seater series was developed from the WA.50 prototype and like the latter, had a composite material construction, but following an entirely different production process. Further changes involved the fitting of a fixed tricycle landing gear, re-contoured rear fuselage lines, larger rear cabin windows, revised vertical and lower-set horizontal tail plane and it also had larger overall dimensions.

WA.51 Pacific: The initial model, of which the prototype first flew on May 17, 1969. This model was powered by an 150 hp Lycoming O-320-E2A engine with fixed pitch propeller. After eleven aircraft had been built it was succeeded by the model WA.51A.

WA.51A Pacific: Very similar to the WA.51, but with minor detail improvements. The WA.51A had a slightly increased area horizontal tail, slightly taller landing gear and provision an extra fuel tank. Production totaled 29 aircraft.

WA.52 Europa: Very similar to the WA.51A, but with now fitted with an 160 hp O-320-D1F engine with a variable pitch propeller and also featuring the increased fuel capacity. The first WA.52 was first flown in 1974, 59 aircraft were built.

WA.53: Largely based on the WA.51, this planned and unbuilt version was a three/four seater with an 125 hp engine. It was intended as a simple trainer/tourer for air club use.

WA.54 Atlantic: The final production model. It was developed from the WA.52, but was slightly longer and it made an engine switch to one more powerful 180 hp Lycoming O-360-A1LD. The WA.54 was equipped with a version of the WA.40 landing gear. After 55 were built, Wassmer Aviation S.A. suspended powered aircraft production in 1977."