But the Portuuese designer of the world's first cloud plane is confident that his revolutionary idea could soon go into production.
Passing Cloud is an idea for a novel mode of transportation designed for the traveller less bothered about the destination than the journey.
Propelled and steered by wind alone the plane would travel around the USA allowing customers a unique insight into life above the chimney tops.
The revolutionary airbus would be constructed from a series of spherical balloons with an inner stainless steel structure covered with nylon fabric. Read More