Solar Impulse: aircraft design optimization using Femap with NX Nastran

By AlRobertson

The goal of Solar Impulse is to circumnavigate the world in a fixed wing aircraft that only uses solar power. The aircraft recently landed in Hawaii, the first port of call in the United States, after a challenging flight that lasted 5 days and nights across the North Pacific Ocean from Nagoya in Japan – the furthest a solar plane has ever flown, and the longest lasting solo flight in aviation history.

The Solar Impulse plane that is currently undertaking this feat is the second aircraft, known as Solar Impulse 2, and is an improved version of the original prototype aircraft. The aircraft certainly is an exercise in efficient design and minimizing weight, with a wingspan roughly equivalent to that of an Airbus A380, the whole plane weighs about as much as a large family car.

Solar Impulse Femap Model
Solar Impulse Femap Model

The engineering team at Solar Impulse has made extensive use of composite materials in the design, to maximize stiffness and minimize weight. The team used Femap with NX Nastran, to help design the composite wing structure as well as the plane’s metal components. Clearly a high degree of structural optimization was required to produce such an efficient design. Use of simulation in conjunction with experience drawn from the first aircraft design led to significant weight reduction through improved material performance, going from a material weighing 100 grams per square meter to one weighing 25 grams per square meter. The Solar Impulse engineers also made good use of the Femap application programming interface (API), writing many scripts to automate a lot of the analysis work.

You can read the full case study to find out more about how Solar Impulse used simulation to optimize the aircraft’s design, making it possible to attempt to circumnavigate the globe without using a drop of fuel.

Congratulations to the Solar Impulse team!

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This article first appeared on the Siemens Digital Industries Software blog at