Solar Impule Around the World


Building and flying a solar airplane is something many consider impossible. To produce this incredible aircraft is one of the challenges the team has already accomplished during the past twelve years. To encircle the globe, Solar Impulse will have to do what no airplane nor human being has done before: Fly through 5 consecutive days and nights without using any fuel.

Piloting and Safety

Very long flight durations, presenting a solo pilot in an unpressurized, unheated cockpit with extremes of temperatures (+40 to - 40 degrees) are the challenge the Bertrand and André are facing in the tiny Solar Impulse 2 cockpit.

Piloting and safety

  • A monitoring system constantly checks the functioning of the autopilot and detects any anomaly or exceeding of safe limits.
  • A man-machine interface provides the pilot with a sensory alert if the bank angle goes beyond the 5° limit.
  • The 3.8 m3 cockpit volume provides enough space on board for oxygen supplies, food and survival equipment, whilst also meeting the ergonomic requirements for flights lasting several days.
  • Self-hypnosis and meditation techniques allow the pilot to maintain his powers of concentration and vigilance.
  • A multi-purpose seat functions both as reclining berth and toilet. A parachute and a life-raft are packed into the seat-back. When fully reclined, it allows the pilot to perform physical exercises.
  • In the absence of any heating, the cockpit and the pilot are protected against the cold outside (-40 degrees) by high-density thermal insulation.

Flight Strategies

  • All possible eventualities simulated by a multidisciplinary team to find the right combination of weather patterns, and pave the way for the solar airplane to enter controlled airspace and prepare for landings at international airports.
  • Takeoffs and landings at night to avoid turbulence and winds of more than 18 km/h. Climbs to 9000m  during the day and descents to 1500m at night to save energy.
  • Mandatory landings every few days to switch pilots.
  • Continuous transmission of hundreds of technical parameters via satellite data-link to mission control centre.
  • Start of the round-the-world flight very early in the season (March) to avoid the Indian monsoon.
Flight Strategies

The Mission Control Center, based in Monaco, is the heart of the entire Mission. The team brings together experts responsible for preparing the flights and missions. They play an important role in providing the pilots with data crucial for following their flight plan.

Technical Solutions

A multidisciplinary team with 80 specialists, 90 partners and about a hundred advisors have developed the largest aircraft ever built with such a low weight. Twelve years of of calculations, simulation, building and testing the first prototype have lead to today - SI2 is now ready to take off.

Technical Solutions

  • Airframe made of composite materials (carbon fibre and honeycomb sandwich).
  • Upper wing surface covered by a skin consisting of encapsulated solar cells, and the lower surface by a high-strength, flexible skin.
  • 140 carbon-fiber ribs spaced at 50 cm intervals give the wing its aerodynamic cross-section, and also maintain its rigidity.
  • Four brushless, sensor less motors, each generating 17.4 hp, mounted below the wings.
  • Energy stored in lithium polymer batteries, whose energy density is optimized to 260 Wh/kg. Their total mass amounts to 633 kg (1395 lbs.), or just over a quarter of the aircraft’s all-up weight.
  • 17,248 monocrystalline silicon cells each 135 microns thick mounted on the wings, fuselage and horizontal tailplane, providing the best compromise between lightness, flexibility and efficiency.