Covestro materials help solar aircraft to fly around the world

The unique Solar Impulse aircraft has completed its journey around the world. What makes it unique? It is powered solely by the energy of the sun. Covestro is a project partner: The pioneering feat would not be possible without the company’s high-tech polymer materials.

Modern and clean technologies can make the impossible possible. Pioneers Bertrand Piccard and André Borschberg proved that and become the first people to circumnavigate the globe in an aircraft powered solely be the energy of the sun: the Solar Impulse 2, or Si2 for short.

The aircraft has the wingspan of a large airliner, yet only weighs as much as a compact car. Solar cells on wings spanning 72 meters power the propellers and charge a battery, which then provides power during the night. This allows the Si2 to fly without interruption and without consuming a single drop of fuel.

Advanced plastics and material solutions from Covestro make the journey possible. Because they do not only make the aircraft simultaneously extremely lightweight and strong, they also protect the pilots from extreme outside temperatures.

“Covestro presented us the best material.”

“We needed the best materials,” explain the co-founders of Solar Impulse. “They have to be as lightweight and strong as possible for us to even fly at all. And they have to offer the best possible insulating performance so that we pilots can survive the extreme temperatures. Covestro presented us the best material and has played a major part in our success.”

The intelligently deployed Covestro materials and raw materials are demonstrating their potential under extreme conditions on this mission. But they also make a healthy contribution to sustainability in everyday life by saving large amounts of energy in cars, buildings and the refrigeration chain.

The materials that make the Solar Impulse and a clean future possible are:

Rigid polyurethane foam

Rigid polyurethane foam is one of the world’s best insulating materials. It is both lightweight and strong. Ideally suited, then, for extreme temperatures ranging from plus 40 degrees Celsius during the day to minus 40 degrees overnight. Ideally suited for a solar aircraft without air conditioning or heating that must be as light as possible.

But also ideally suited for energy-plus buildings and energy-efficient refrigeration equipment.


Transparent, extremely strong, freely formable, a good insulator and only half as heavy as glass. These are the properties that make the high-performance plastic polycarbonate the perfect material for the cockpit glazing of the Si2.

But polycarbonate isn’t found just in the innovative solar aircraft. The material is also used for rugged electronics, safe stadium roofs, lightweight automotive components and much, much more.

Polyurethane coating

A large portion of the aircraft’s hull is covered with a shiny silver coating formulated with polyurethane raw materials that reflects the sun and is impervious to the wind.

Thanks to new process technology, such paints and coatings can be produced with less solvent, require less heat to dry or are even self-healing. In everyday life they protect cars and bridges from the elements and rusting.