The Soviets were developing a new class of vehicle that could move as fast as an aircraft, but lift far more payload than a conventional airplane. These machines would fly metres from the surface using an aerodynamic principle called the ground effect. They were called Ekranoplan (roughly translating to mean for "screen plane" or "low flying plane"). Beginning with experiments in the early 1960s, and headed by a pioneering hydrofoil engineer Rostislav Alexeyev, the Soviets quickly developed a series of small-scale prototypes to refine the concept. In 1966 they completed the KM (Korabl Maket) Russian for "ship-prototype". An enormous machine, larger and heavier than any aircraft in the world. The first large scale Ekranoplan could lift an astonishing 544,000 kg (1,199,315 lb) and reach speeds of over 600 km/h (373 mph).