TYPES OF WIG-CRAFT
WIG-craft are not aircraft. Complications from the proximity to the ground, creates an additional design criteria that is not required for aircraft designs. Both, flying close to a surface, and long relative take off distances (compared to aircraft) require a WIG craft to be vertically auto stable.
Secondly, the small wings on a WIG Craft don’t create as much lift an aircraft, so take off often requires significantly more power than flight.
Over the years, different WIG-craft designs have been developed, with each design finding different ways to address the stability and take-off issues. The following highlights the most common designs.
This early platform was first created by Lippisch. The reversed delta wing is very stable because of its wing platform. As a result, only a small horizontal stabilizer is necessary.
One down side to these craft, is that the power required to get over the hump speed of the hull can be twice that of cruising. As a result, once the craft is flaring the power can be reduced by 50% for cruising, meaning more engine is on board than is needed. These craft also have a limited range of speed between take off and cruise, do to the twist in the wings. These designs typically utilize V-hulls similar to a speed boat. These crafts can also “jump”.
Some examples of Reverse Delta WIGs include the Lippisch X-112, X113, X114 and the Airfisch series. The Lippisch X114 and the Flightship FS8 are shown here.
The tandem wing concept uses two small wings in line. The wings are set in different angles in respect to each other. This configuration provides excellent stability. No horizontal stabilizer is necessary, but the flaring height is relatively low.
Large models use separate engines for trust and under wing blowing in front of the wing. All Ekranoplans have huge horizontal stabilizers. These crafts are also called PAR-WIG crafts (Power Augmented Ram Wing in Ground Effect). Many have been built in different sizes, the largest exceeding 500 tons. Russian companies are the only companies who can deliver now.
In dependent of efficiency, these crafts do have the advantage that they can drive up on a beach while supported on cushion.
At a speed of about 43 knots the aerodynamic lift from the wings can support the craft in WIG mode. At this point, the lift fan can be switched to neutral and no longer draw power from the engine. Because this craft hovers before take off, it can also be used on land, ice or snow.
See the SE Technologies page used to be a great resource for more examples.