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Worlds First Wing in Ground Effect Marine Craft fully surveyed to IMO Rules. Manufactured in Australia. Picture provided by new owners in Singapore.

The FS8 should already be appointed a thrifty, environmentally friendly successor of the seaplanes in the Maldives Islands since 2003. Why the machines then weren't acquired despite a great announcement in the Maldivian media anyway is unknown. Probable isn't the FS8 sufficiently fit to fly at only 2m of altitude over the high swell between the atolls anyway.

The Dragon Commuter is an extremely high speed, highly efficient marine vessel. Registered, operated and maintained at typically low marine craft overheads. The FS8 lifts totally clear of the water surface to ride a self-generated airwave at speeds above 55 knots. The primary function of the FS8 is for economical, over water transportation in tropical regions of the world of either 2 crew plus 8 passengers or 2 crew plus 840 kgs payload. The Dragon Commuter is only available to commercial operators with certified crews trained at the Flightship Training School (FTS).

By virtue of a Flightship's aerodynamic design, sustainable free flight is not possible above ground effect. Under United Nations International Maritime Organisation (IMO) legislation, ground effect craft are recognised universally as marine vessels for construction, insurance, operator licensing and registration requirements. The purchase and operating costs are therefore considerably less than traditional aircraft, while still being able to travel at a speed comparable to a light aircraft.

The Dragon Commuter has a maximum water surface clearance capability of up to 2 metres over the crests of 2 metre waves. A range of up to 300 nm, a cruising speed of 170 km/h (86 knots) is achievable and the range reserves are over 4 hours of operation. The FS8 is moulded and fabricated from low maintenance FRP composites. Waterborne propulsion is provided by silent, retractable electric thrusters in the wing tip floats. Maximum external noise emission in the cruise mode is 75 dBA at 100 metres. This is far less than a heavy diesel truck @ 90 dBA on the highway or a jet aircraft taking off at 125 dBA.

All design and construction details for every craft built are under International Shipping Registry Classification with Germanischer Lloyd. Crew training and operating safety standards for the FS8 are based on IMO HSC high speed code operational standards. This ensures the highest levels of quality are rigidly maintained in every phase of production. Standard equipment provided with the FS8 includes SOLAS life jackets, life rafts, flares, VHF radio, depth sounder, ECDIS and computer navigation system, GPS, radar transponder, 15nm MARPA forward looking radar, pitch and roll alarm presets, altimeter, air speed indicator and full cabin air conditioning to tropical capabilities.

Ground effect is still the most efficient form of powered flight known to man. The Wright brothers used ground effect when they flew their first aircraft the 'Flyer' in 1903. It took a further six years for the brothers to find an engine big enough and light enough to lift the same aircraft out of ground effect into free flight. When an aerodynamic wing is close to a ground plane, such as water, lift is increased by as much as 45% and induced drag decreased by up to 70%. This is vastly different to normal operation of an aircraft wing in free flight away from the ground. The main benefits when a craft is operating within ground effect are that speed, payload and fuel economies are considerably more efficient than with traditional boat, plane and helicopter transport. Span dominated ground effect results in a reduction of induced drag (D). Chord dominated ground effect results in increased lift (L). The overall effect of both span and chord dominated effects is an increase of the L/D ratio.

The typical cruising speed of the PBY was 100 to 120 miles per hour or 90 knots.

Can cruise at 50 to 70 knots. The aircraft had an enormous range and loitering capability with an over all range from 2,500 to 2,900 miles and a service ceiling of 15,000 to 22,400 feet. The PBY is a large high wing monoplane with a total wingspan of 104 ft. and a total wing area of 1,400 square feet. The aircraft measures in at 63 feet 10 inches and has a gross weight of 31,800 pounds to 36,000 pounds.

BY WILLIAM COLE

It would be the biggest bird in the history of aviation.

Dwarfing all previous flying giants, the Pelican, a high-capacity cargo plane concept currently being studied by Boeing Phantom Works, would stretch more than the length of a U.S. football field and have a wingspan of 500 feet and a wing area of more than an acre. It would have almost twice the external dimensions of the world's current largest aircraft, the Russian An225, and could transport five times its payload, up to 1,400 tons of cargo.

Designed primarily for long-range, transoceanic transport, the Pelican would fly as low as 20 feet above the sea, taking advantage of an aerodynamic phenomenon that reduces drag and fuel burn. Over land, it would fly at altitudes of 20,000 feet or higher. Operating only from ordinary paved runways, the Pelican would use 38 fuselage-mounted landing gears with a total of 76 tires to distribute its weight.

The military, commercial and even space prospects for such a cargo plane—officially known as the Pelican Ultra Large Transport Aircraft, or ULTRA—are also huge.

"The Pelican can broaden the range of missions for which airplanes are the favoured way to deliver cargo," said Boeing's Pelican program manager Blaine Rawdon, who is designing the plane with Boeing engineer Zachary Hoisington . "It is much faster than ships at a fraction of the operational cost of current airplanes. This will be attractive to commercial and military operators who desire speed, worldwide range and high throughput. We envision that the Pelican can multiply aircraft's 1-percent share in a commercial market now dominated by container ships."

John Skorupa, senior manager of strategic development for Boeing Advanced Airlift and Tankers, said, "The Pelican currently stands as the only identified means by which the U.S. Army can achieve its deployment transformation goals of deploying one division in five days, or five divisions in 30 days, anywhere in the world." If necessary, he said, the Pelican could carry 17 M-1 main battle tanks on a single sortie. Commercially, the aircraft's size and efficiency would allow it to carry types of cargo equivalent to those carried by container ships, at more than 10 times the speed.

"It is attracting interest as a mother ship for unmanned vehicles, enabling rapid deployment of a network-centric warfare grid, a likely future mode of operation for modernized U.S. forces as demonstrated in Afghanistan ," Skorupa said. "And it is attracting interest as a potential first-stage platform for piggybacking reusable space vehicles to an appropriate launch altitude.

"Why would such a huge airplane be flown at such a low altitude?

By flying low, the Pelican, like its name-sake, exploits the aerodynamic benefits of a well-known phenomenon called ground effect. Flying close to water, the wing downwash angle and tip vortices are suppressed, resulting in a major drag reduction and outstanding cruise efficiency.

"It's an effect that provides extraordinary range and efficiency," Skorupa said. "With a payload of 1.5 million pounds, the Pelican could fly 10,000 nautical miles over water and 6,500 nautical miles over land.

"Flying in ground effect demands the latest flight control technology, conceded Skorupa. Reliable systems will provide precise, automatic altitude control and collision avoidance. Cruise altitude will be adjusted according to sea state, and if the seas get too rough, the Pelican can easily climb to high altitude to continue the flight.

When could the Pelican be flying? The answer may lie in the Army's Advanced Mobility Concepts Study, scheduled for release next April. The Pelican has been offered by Boeing as part of a system-of-systems solution that would include the C-17 Globe master III transport, the CH-47 Chinook helicopter and the Advanced Theatre Transport.

"A favourable report would set the stage for a possible co development effort between Boeing, the U.S. military and interested commercial cargo carriers," Skorupa said.

A concept for a colossal cargo aircraft designed to skim a few metres above the surface of the ocean has been revealed by researchers at the aerospace company Boeing.

The concept aeroplane, called the Pelican Ultra Large Transport Aircraft (ULTRA), would exploit an aerodynamic phenomenon known as the "wing-in-ground effect" to glide just six metres above the waves.

Riding on top of a cushion of air, the airplane would experience 70 per cent less drag than a normal plane and could therefore travel further using the same amount of fuel.

Measuring 152 metres from nose to tail and with a wingspan of 109 metres, the Pelican ULTRA would be the largest plane to ever fly - if it is built. The world's largest existing plane, the Russian Antonov 225, is 84 metres long. The Pelican ULTRA is designed to carry 1400 tonnes of cargo over a distance of 16,000 kilometres in one journey.

The wing-in-ground effect occurs at an altitude equivalent to 10 to 25 per cent of the wing's width at the point where it joins the fuselage. The effect increases the ratio of lift to drag for a wing. The phenomenon has been investigated for a wide variety of aeroplanes in the past because it offers potentially large cost savings.

Over land, the Pelican UTLRA would travel at a more conventional altitude of 6000 metres or more.

manager of strategic development for Boeing Advanced Airlift and Tankers, adds: "Cruise altitude will be adjusted according to sea state, and if the seas get too rough, the Pelican can easily climb to high altitude to continue the flight."

Engineers at Phantom Works, the Boeing research department responsible for Pelican ULTRA, say the airplane could have numerous military and commercial users. It could carry 17 tanks at ten times the speed of any container ship.

The Pelican ULTRA has been proposed as part of a military transport project and positive conclusions from the US Army's Advanced Mobility Concepts Study, due in 2003, could set the stage for development.

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Wing In Ground effect aerodynamics

Ever since the beginning of manned flight pilots have experienced something strange when landing an aircraft. Just before touchdown it suddenly feels like the aircraft just does not want to go lower. It just wants to go on and on due to the air that is trapped between the wing and the runway, forming an air cushion. The air cushion is best felt in low wing aircraft with large wing areas. This phenomenon is called (aerodynamic) ground effect. The Wright brothers probably have not even flown out of ground effect in their early flights, they benefited from ground effect without even knowing it existed.

Around 1920 this effect was first described and some (theoretic) research was carried out in this field (e.g. ref.840). From that time on pilots knew ground effect and sometimes even used it on purpose. The seaplane Dornier DO-X could only cross the Atlantic when it was flying with its hull just above the wave crests. In the second World War pilots knew that when they lost an engine or fuel on the way back from the enemy that they could reach home by flying just a few metres above the sea, thus needing less power and saving fuel.

Dornier Do X

Two phenomena are involved when a wing approaches the ground. Ground effect is one name for both effects which is sometimes confusing. These two phenomena are sometimes referred to as span dominated and chord dominated ground effect. The former results in a reduction of induced drag (D) and the latter in an increase of lift (L). The designations span dominated and chord dominated are related to the the fact that the main parameter in span dominated ground effect is h/b (height/span), whereas in chord dominated ground effect it is h/c (height/chord).

The high pressure air cushion can clearly be seen in the illustrations. The pressure around an airfoil has been calculated with and without ground effect, both at a five degree angle of attack. In free air the (2D) lift coefficient was 0.8 and at a ground clearance of 0.05 times the chord it was 1.1. The high pressure at the bottom of the airfoil in ground effect is caused by the ram effect. The nose suction peek is also somewhat more pronounced in ground effect, which indicates that separation is likely to occur at the nose. This has been confirmed by wind tunnel tests.

Ground effect not always increases lift. It is possible under certain conditions that lift reduces when an airfoil approaches the ground. This is the case when the bottom of the foil is convex and the angle of incidence is low, in that case a venturi is created between the foil and the ground where high-speed low-pressure air sucks the airfoil down. This is illustrated with 2D calculation results below. This venturi-type ground effect, albeit more extreme, is used by race car designers to make it "stick" to the road at high speeds.

These graphs illustrate lift decrease due to ground effect, they were made using the Airfoil Calculator

Some wing plan forms are more stable than others, the reversed delta from Lippisch proved to be very good, therefore it has been very popular lately (e.g. in the Airfisch series craft). Not only the plan form, but also the wing section is important for stability. Recent research showed that wing sections with an S-shaped camber line are more stable than conventional wing sections. Many new designs have such an S-foil.

Example of a special wing section for ground effect, its has a pronounced S-shape at the bottom only, this graph was generated with the Airfoil Calculator

Although the design of the upper side is less important than the lower side, here also some general rules apply. The nose radius of the profile must not be too small because that may lead to very early separation in strong ground effect. Furthermore an S-shaped camber line is favourable for stability, so with a given (non S-shaped) bottom this leads to a very pronounced S-shaped upper side.

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Wing In Ground effect aerodynamics

Dornier Do X

From Wikipedia, the free encyclopedia

Specifications

Span dominated ground effect

Chord dominated ground effect

L/D ratio

Longitudinal stability

Ground effect wing sections