Phoenix demonstrator variable buoyancy aircraft

A partnership of universities and private companies led by Andrew Rae of the University of the Highlands and Islands Perth College in Scotland, have developed and flown what is claimed to be the first aircraft powered by variablebuoyancy propulsion. In March, the unmanned Phoenix prototype made an indoor maiden flight at the Drystack facility in Portsmouth, England, where it repeatedly flew for a distance of 120 m (395 ft).