Ground Effect Vehicle - Advantages and Disadvantages

Advantages and Disadvantages

Given similar hull size and power, the reduced lift-induced drag experienced by a ground effect craft will improve its fuel efficiency over that of a similar aircraft, and less power will be required for a similar speed up to a point. The difference is dependant on the specific designs and how well designed the ground effect vehicle is. At the same time it is much faster for a given amount of power than a similar surface vessel as drag from contact with the water is eliminated.

On the surface of the water the aircraft construction methods that allow it to fly increase damage caused by contact with other vessels while being more difficult to escape from due to the limited number of egress points.

Since most are designed to operate from water, an engine failure may be less hazardous than in a land based aircraft, but the lack of altitude will leave fewer options to the pilot, negating this benefit. Low altitudes brings high speed craft into conflict with ships, buildings and rising land, which may not be sufficiently visible in poor conditions to avoid, and the ground effect vehicle may be unable to climb over or turn sharply enough to avoid them while drastic low level maneuvers risk contacting the earth's surface. The FAA uses the term "controlled flight into terrain" for the primary cause for many aircraft accidents - and they can climb over most obstacles, while ground effect vehicles are more limited.

In high winds, takeoff must be into the wind, which means across successive lines of waves which causes a heavy pounding which both stresses the craft and makes passengers uncomfortable. In light winds, waves may be in any direction, which can make control difficult as each wave causes the vehicle to both pitch and roll. Their light construction limits their ability to operate in higher sea states than conventional ships, but not so much as with hovercraft or hydrofoils which are closer to the surface of the water. The demise of the seaplane was a result of its inability to take off or land due to sea conditions even while flying conditions were good and its use only lasted until runways were made available. Ground effect vehicles are likewise limited.

Like conventional aircraft, greater power is needed for takeoff, which like a seaplane must first get on the step, breaking the suction of the water which holds it down, before accelerating to flight speed. Careful design, and usually multiple redesigns of hullforms that are still more art than science is required to get this right, increasing engineering costs for ground effect vehicles with short production runs. For the ground effect vehicle to work, its hull needs to be stable enough longitudinally to be controllable, yet not so stable it can't be pulled off the water, while the bottom must be formed to avoid excessive pressures on landing and taking off, without sacrificing lateral stability too badly, and finally it must not create too much spray, which damages the airframe and the engines. The Russian Ekranoplans show evidence of fixes for just these problems in the form of multiple chines on the forward part of the hull undersides, and in the forward location of the jet engines.

Finally, limited utility has kept production levels low where it has been impossible to amortize development costs sufficiently to make them competitive with conventional aircraft.