Boeing's 'big bird' unveiled

An advanced concept plane, which if built would be the largest aircraft ever to take to the skies, is being studied by Boeing.

Designed to carry huge amounts of cargo over vast distances, the Pelican's unorthodox design would allow it to 'skim' about 6 metres (20ft) above the ocean, taking advantage of reduced air resistance.

With a wingspan of 500 ft and fuselage longer than a football pitch, the Pelican would dwarf all current heavy-lift aircraft, including the world's largest aircraft, the Russian Antonov An-225.

It could carry up to 1,400 tonnes of cargo, five times the Antonov's payload.

The Antonov An 225 is the world's largest plane

Over land the Pelican would fly at altitudes of 20,000 feet or higher.

Operating from ordinary airports, it would use 38 landing gears equipped with 76 tyres to carry its weight.

A measure of the Pelican's vast scale is that Boeing envisages its main competitors as container ships. Its potential military uses are also being explored.

The Pelican could carry 17 M-1 tanks at a time, and would fulfil the US military's goal of the ability to deploy a whole division in five days, or five divisions in 30 days.

Space possibility

Its possible use as a 'piggyback' plane, carrying spacecraft to the edge of the earth's atmosphere, is also being considered.

The Pelican is just one of several advanced aircraft designs being studied by Boeing's advanced aviation research wing, Phantom Works.

Another, the Sonic Cruiser, a 250-seat passenger plane, would fly up to 20% faster than conventional jets.

However, BBC transport correspondent Simon Montague says there is no guarantee either will ever actually be built.

Analysts say the current climate of uncertainty in the aviation industry mean that more than ever, concept aircraft must have clear commercial potential if they are to become reality.