Flight Club reports: [edited]
Flown by German test pilot Markus Scherdel, the Solar Impulse 2 departed from Payerne Airport in Switzerland on 2 June at 5:30am and landed at 7:50am local time.
Solar Impulse 2 has a wingspan of 236 feet - larger than a Boeing 747-8i. However, the SI2 only weights about 1 percent of the 747. With a structure made of composite materials and wings covered in sheets of wound carbon fiber, it's truly the most energy efficient plane ever made, outside of an engineless glider. The wings, fuselage and horizontal stabiliser are covered in 17,248 solar cells, at 135 microns thick, which provide energy to the plane's four engines.
Lithium polymer batteries power the four 17.4hp engines, weighing a total of 1,395 pounds, make up a quarter of the plane's total weight. The two-bladed propellers spin at 525rpm. The system is 94 percent efficient.
26 knots is all the speed it takes to get the Solar Impulse 2 airborne, using roughly 500 feet of runway. It can cruise up to 27,000 feet at speeds ranging from 31.5 to 77 knots. At sea level, it only has to fly at 20 knots to remain airborne.