MATT SHEAHAN

WE’RE USED TO FOILING BOATS BUT WHAT ABOUT CRAFT THAT FLY JUST ABOVE THE WATER? IT SEEMS GROUND EFFECT’ VESSELS ARE MAKING A COMEBACK

The Caspian Sea Monster was every bit as intimidating as its name suggests. At over 100ft long it flew at 230 knots just 20ft above the water's surface. With a lift capacity of 550 tonnes and 10 jet engines spread along its stubby wings and tail fin it was a beast of a machine.

Known officially as the Korabl Maket KM) it was the largest in a line of ground effect aircraft designed and built in the Soviet Union from the late 1950s through to the mid-1980s as part of the Ekranoplan project.

Despite having unusually short wings the KM could cover long distances at high speed as well as being able to carry much higher payloads more efficiently than a conventional aircraft of a similar size. In theory it was a winner, but in practice there were problems.

Maintaining stable flight close to the surface was said to be challenging for the pilots and when the sea state built it became difficult, if not impossible, to operate.

Manoeuvring was also an issue and required plenty of advanced warning to avoid obstacles. And then there was the issue of getting airborne in the first place. While the Sea Monster was efficient in flight it took a huge amount of power to get there. So, by the end of the 1980s as the Cold War started to thaw, the Ekranoplan project had pretty much fizzled out for the big beasts. But development in smaller ground effect vessels continued.