High-tech materials help innovative design take flight

Si2’s innovative design was made possible with lightweight and strong materials from Covestro. (Photo credit: Solar Impulse)

February 16, 2017 – With an eye on innovation, Covestro is continually helping to achieve the impossible with its high quality materials. In late July 2016, the company was part of aviation history as Solar Impulse 2 (Si2) – an airplane powered solely by the sun – completed its historic journey as the first plane to fly around-the-world without using a drop of fuel. Si2 was designed with several crucial materials from Covestro that helped make the impossible possible.

With the wingspan of a large airliner, Si2 is extremely lightweight – only weighing as much as a compact car. Solar cells span 72 meters on the wings to power the propellers and charge the batteries – enabling the plane to fly day and night without using any fuel.

This amazing feat was the mission of pilots Bertrand Piccard and André Borschberg, along with a team of 90 engineers, technicians and mission controllers. Several factors contributed to the success of Si2 – an important one being the plane’s unique, strategic design. With a need for lightweight and strong materials, the pilots relied heavily on advanced plastics and material solutions from Covestro to make this worldwide journey possible.

Covestro designed and constructed the Si2 cockpit shell, which is made of rigid polyurethane foam and weighs only 30 kilograms. Since the plane functioned without air conditioning or heating, this highly insulative polyurethane foam was essential for protecting the pilot from extreme temperatures as low as -40ºC overnight and over 40ºC during the day. Not only does the polyurethane foam provide much-needed insulation, but it is also energy efficient – saving 70 times more energy than is used to make it.

Si2’s windshield required a material that was lightweight and featured superior impact resistance, yet had the same visual quality as glass. At less than half the weight, polycarbonate from Covestro provided glass-like performance. Polycarbonate offers scratch-resistance, impact-resistance, excellent insulation, transparency and strength – making it the ideal choice for the plane’s windshield glazing.

With flights that lasted days, comfort was an important factor for the Si2 pilots. To help with this, a solution based on Covestro’s thermoplastic polyurethane (TPU) films was used in the pilot’s seat. The pilot was then able to customize the seat firmness by inflating it or releasing air. Lastly, Si2’s distinctive silver finish was made possible with a polyurethane-based coating from Covestro. Found on the plane’s wings, this coating reduced wind resistance and helped to reflect the sun.

With so many material innovations onboard, it’s no wonder Si2 was dubbed a “flying laboratory” of Covestro technologies.

For more information, email plastics@covestro.com.

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