Refurbished Solar Impulse 2 returns to the skies

Refurbished Solar Impulse 2 re...
Solar Impulse 2 is expected to continue its journey at the end of April
Solar Impulse 2 is expected to continue its journey at the end of April
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Solar Impulse 2 is expected to continue its journey at the end of April
Solar Impulse 2 is expected to continue its journey at the end of April

Following a seven-month grounding in Hawaii, Solar Impulse 2 is preparing for a return to its historic round-the-world sun-powered flight. The team has carried out a maintenance flight to test out newly installed systems and plans to recommence its journey with a four-day flight in two months time.

The single-pilot Solar Impulse 2 took off from Abu Dhabi last March with the lofty goal of flying around the globe powered only by the sun. Its last five-day leg from Nagoya, Japan to Hawaii was largely successful, with the crew nabbing solar aviation world records for longest distance, duration and solo flight.

But the record-breaking trip came at a cost. As the team carried out its inspections in Hawaii it discovered severe damage to the plane's batteries. Over-insulation during ascent on the first day of the trip caused them to overheat, and while the team was aware of the problem there was no way to lower the temperature with the plane in the air.

The team has now made repairs to Solar Impulse 2, including the installation of new batteries, stabilization and cooling systems, enabling it to take the air once again in a 90-minute test flight. This saw the plane ascend to 8,000 ft (2,438 m) over the Pacific Ocean during the recent test flight, with the crew observing the new systems in action and reporting that everything ran as planned.

If there are no more hiccups in the short-term, Solar Impulse 2 is expected to continue its journey at the end of April, first in a four-day flight from Hawaii to the west coast of the US and then eventually back across to Abu Dhabi.

Source: Solar Impulse

The first part of the trip up until the flight from Japan to Hawaii was mostly accomplished in short trips. The trips planned for the 2nd half are longer it looks like. They have had 8 flights so far and have 5 left.
Other than the one stop in "mid USA" the remaining flights are pretty long.
Anyone know the cost of this project?
I don't quite understand the point of this. They spend millions to do this. Then they fail to continue flight - because the battery got fried and then they spend half a year rebuilding the thing for millions to continue? And for what.. to proof that one can do a long solar flight - with lots of pitstops in between and millions of dollars in maintenance and months of wait times between stops? Just seems odd to me! Rather donate that money to do some real good.
Douglas Bennett Rogers
The main achievement is the ability to stay up w/o refueling or gas bag until repairs are needed.
ok so the goal is to stay up without refueling until repairs are needed. So using gas guzzler terminology.. they managed to do smaller segments.. then landed and had to replace the gas tank.. and not had to refuel. Not sure how replacing the gas tank (or batteries) is progress. Show me a round the world flight just on solar.. then we're talking. But these little puddle jumps with months and millions in between.. really?
Bryan Allen
Answering Augure's question, the project cost so far has been 170,000,000 Euros.
@Bryan Allen thanks for the answer. I guess this is budget for both Solar Impulse 1 and 2.