A lot has been happening over the summer months in the Solar Impulse hangar in Dübendorf near Zurich. The fuselage of the prototype has passed its first static load tests and has been certified airworthy, confirming the choice of technologies and construction design for the solar airplane which have until now never been used in the aviation industry. This goes to prove that the structure of the first prototype, officially known as HB-SIA, meets the exceptional challenges of this unique pioneering project, which require it to be extremely robust and at the same time ultra-light, resistant and controllable. All the time considering its wing span of 61 metres and weight of only 1,500 kg. A milestone on the way to the first manned round-the-world flight in a solar airplane!

The latest Solar Impulse Insight video clip “Fuselage Tests” lets you experience the tension and excitement during the static load tests to check the plane’s bending and torsion behaviour under real maximum load conditions.

None of the engineers and technicians were able to predict the final results of the tests and consequently tension was running high in the Solar Impulse hangar at the start of the fuselage tests. Would the cockpit, the axles or the tail – the result of many years of research, calculations, simulations and tests – rupture? Would the fuselage bear the strain? The Solar Impulse team held their breath as 900 kg of lead were attached to the cockpit and 300 kg to each of the three axles. The load was gradually increased – first 20%, then 50, 75 and finally 100%. Several hours of tension – both for the team and the test specimen – were followed by elation, applause and relief once the structure of the prototype had passed its final test. And the tension and excitement are expected to remain before the first test flights in early summer 2009. In the next few weeks the wings are due to be delivered in three gigantic boxes to be tested in the Solar Impulse hangar.

The official Solar Impulse log book, which can be subscribed to free of charge in the form of a quarterly newsletter [here], and the website will keep you up-to-date with background information on all aspects of the pioneering project. Test your inquisitiveness!