SI2

Zero-fuel Solar Impulse 2 (SI2) will halt its round-the-world flight until early April 2016 over a major failure of its batteries due to overheating.

Earlier this month, the solar-powered aircraft has completed its eighth stage trip from Nagoya, Japan, to Hawaii, US.

During the record 117h and 52min flight, the SI2 batteries overheated due to a high-climb rate and an over-insulation of the compartment.

Solar Impulse said on its website: "The damage to the batteries is not a technical failure or a weakness in the technology, but rather an evaluation error in terms of the profile of the mission and the cooling design specifications of the batteries."

"The damage to the batteries is not a technical failure or a weakness in the technology, but rather an evaluation error in terms of the profile of the mission and the cooling design specifications of the batteries."

Damage to certain parts of the batteries is irreversible and requires repair work, which is expected to take several months.

The engineering team will explore various options to create better cooling and heating processes for long-distance flights.

While the maintenance is undertaken, the aircraft will be kept in a large hangar at Kalaeloa Airport.

The new battery heating and cooling systems will be evaluated prior to resuming the round-the-world mission.

From Hawaii, the SI2 will fly to US mainland and then continue across North America, via Phoenix, mid-US and New York, before flying over the Atlantic to Europe, and on to Abu Dhabi.

Solar Impulse said it plans to complete the first ever global flight next year, and the latest delay will have no impact on the programme.

Image: SI2 reached Hawaii on 3 July. Photo: courtesy of Solar Impulse.