z Global briefing
06 |^
APRIL 2015
AEROSPACETESTINGINTERNATIONAL.COMAROUND THE WORLD
IN NON-WEIGHTY DAYS
After an 11-hour stop in Muscat (Oman),
Solar Impulse’s attempt at the first round-
the-world solar flight continued onward to
India. Bertrand Piccard took the controls from
CEO and co-founder André Borschberg,
piloting Solar Impulse 2 (Si2) from Muscat to
Ahmedabad (India), across the Arabian Sea. In
doing so, he traveled 1,468km, setting a
straight distance world record (subject to
validation by the FAI (Fédération Aéronautique
Internationale)). Borschberg had previously
held the record for straight distance, pre-
declared waypoints (1,386.5km), for the Si
Across America mission in 2013. At the time of
going to print, Si2 had been delayed in India,
but had finally completed the fourth leg of its
journey to Mandalay in Myanmar (Burma) in
its historic bid to fly around the world. zTest pilot Markus Scherdel took Solar Impulse 2 (HB-SIB) up for its
initial flight at Payerne, Switzerland, on June 2, 2014. The aircraft
reached an altitude of 1,670m during a two hour and 17 minutes-long
flight. This was followed by a high-tempo test campaign to prove
HB-SIB in the run-up to its round-the-world attempt.
Scherdel was also in the cockpit when the first aircraft, Solar Impulse 1
(HB-SIA), completed its maiden flight in April 2010. The following month
it went on to achieve a first flight using exclusively solar power. The first
two all-solar flights completed an initial circuit using energy stored in
the batteries, and a second in which the solar panels were activated,
allowing the batteries to recharge.
The next milestone came in July 2010, when HB-SIA carried out the
world’s first manned 26-hour (day and night) solar-powered flight. André
Borschberg was at the controls for the mission, which was flown from
Payerne. By now, Solar Impulse 1 was operating at a maximum altitude
of 8,700m. At this height the sun’s rays supplied the solar cells. During a
slow descent, before sunrise, energy stored in the batteries was used.
In May 2011, HB-SIA flew from Payerne to Brussels, in a 13-hour flight
that marked its first international transit. The aircraft recorded an
average altitude of 1,800m and an average speed of 50km/h. The flight
served to prove operations in international airspace, with the slow-flying
aircraft operating below commercial traffic routes. A debut international
flight followed in June 2012, from Madrid to Rabat in Morocco.
While HB-SIA continued to push the envelope, construction was already
underway on Solar Impulse 2. Structural tests were carried out between
May 2012 and October 2013, but in July 2012 a wing spar broke during
torsion tests. A replacement spar arrived later that month and was
subjected to further tests, which proved it capable of withstanding the
planned 4.9-ton load. The next set of structural tests exposed the spar
to bending, at loads up to 3.5 tons across both axes.
The broken spar delayed the planned round-the-world flight from 2013
to 2015. Instead, a flight across America was scheduled for HB-SIA.
This took place in multiple stages during summer 2013.
SOLAR IMPULSE FLIGHT-TEST MILESTONES