Design: Aerodynamic Lift - A2V’S Outlook
It is difficult to call her a boat but A2V is nevertheless a boat. Her strange shell shape allows her to exploit every boat’s condition which means being situated on a plane dividing water and air.
Any boat yacht or ship travels on a plane which separates two fluids: water and air. Other conventional vehicles such as trains, aircraft, motor cars do not share this unique condition pertaining to water craft since they move through air alone. On one hand when two fluids are involved they determine wave formation which inevitably causes drag effect to water craft or resistance to forward motion when in head seas, but on the other hand wave trains can produce an advantage in terms of energy obviously! Several solutions to best exploit this special situation have been developed over time but with little success and have scarcely been deployed even in SES or Surface Effect Ships and in ground effect vehicles, that are essentially rare marine craft which many probably have never even heard of. Surface effect ships are in fact half way between catamarans and hovercraft since they resemble catamarans but they’re partially “lifted” by an air cushion generated via blowers entrapped between their two lateral hulls and by “skirts” installed in the bow and stern ends. Ground effect vessels are closer to aircraft than they are to boats since they fly just few metres above water skimming the surface on an air pad which is installed under each wing thereby exploiting what insiders call WIG or Wing In Ground effect. Obviously ground effect wings produce
the same lift as the wings of every aircraft does but with added ground effect. The idea of unifying the principles of both these vessels was conjured up scores of years ago to obtain a single watercraft capable of remaining upright on the water. It had been envisaged by several engineer designers. One such great person was Sonny Levi who passed away back in the seventies after having revolutionised the concept of planing hulls and the offshore racing world by introducing efficient fairing featuring consistent lift effect installed above the waterline along the topsides of his very fast award winning racing hulls. Aerodynamic lift was the most important element in his most revolutionary boat, “Arcidiavolo” which featured twin catamaran hulls in the bow which aft became a single hull in the stern end. These racing hulls’ leading problem was and is still “take Above on the left,the SES, Surface Effect Ship, is a catamaran which partially lifts from the water thanks to an air bubble created by specially designed blowers. The air bubble is entrapped between the two lateral hulls and by two skirts situated at the bow end and stern. In the two pictures , Umoe Ventus a 27 metre SES which exceeds 30 knots and built to carry crews from and two offshore oil rigs. The picture with the blowers in action clearly shows how the SES lifts in relationship to the picture in which it is not moving. Above on the right, Ground effect aircraft exploit WIG (Wing in Ground effect). KM1 shown in the picture is the largest ever built. It is 100 metres long with a beam of 40. It used to fly at 500 kph. It was built in the USSR during the cold war years. The Americans called it the Caspian sea’s marine monster.
Arcidiavolo was the first vessel featuring aerodynamic advancement which was both well balanced and adequately controlled. It can be recognised easily due to its very special three point hull, or upturned tricycle hull as designer “Sonny” Levi liked to describe it.