US balloonist Steve Fossett is heading over the Pacific as he steers his craft towards strong breezes he hopes will speed him on his quest to be the first to float solo round the world.

Mr Fossett, who launched near Perth on Wednesday, is hoping to get a jet-stream assisted journey as he travels eastwards over New Zealand and the South Pacific.

After one day and 18 hours aloft he had completed 3,500 miles (5,600-km) of his 17,000 to 18,000 mile (27,000 to 29,000 km) route.

If he continues at his current rate of 51.3 mph (82.6 km/h) his Freedom of Spirit balloon could clear the Pacific in only five days.

And if the easterly winds hold, he could achieve the circumnavigation in under two weeks, comfortably within his planned 16- to 20-day journey plan.

Mr Fossett was travelling at an altitude of about 21,000 ft (6,400 metres).

Crash landing

The only cloud on the horizon is a bad storm front over New Zealand, but Mr Fossett, 58, is hoping it will soon blow over.

His last flight in August last year foundered in Brazil with a crash landing, but it was still the longest recorded solo balloon flight.

The balloon uses a mixture of helium and hot air

If he crosses South America this time, he is hoping to pick up more jet streams to speed him across the Atlantic and Indian Oceans.

The millionaire former Chicago markets trader has been free of technical problems which have blighted his previous airborne expeditions.

"This is all looking good, I'm even able to sleep, which I've never been able to do on the first night of a flight," he said.

His capsule measures 2.5 x 2.5 metres (8.2 feet x 8.2 feet) and is 1.6 metres (5.2 feet) high. Mr Fossett is breathing oxygen through a mask and eating military-style rations.

The Spirit of Freedom uses a mixture of helium and hot-air and is steered by rising or descending to catch favourable winds.

Mr Fossett was beaten in the attempt to be the first to circle the globe in a balloon by Swiss pilot Bertrand Piccard and English co-pilot Brian Jones in March 1999. He then embarked on his solo quest.

In 1997, his first attempt ended in a crash landing in Russia and the following year he narrowly escaped death when a storm sent him plummeting 29,000 feet (8,800 metres) into the sea north-east of Australia.

This time many modifications have been made to plans and equipment and Mr Fossett said he was "optimistic".