Today my ipad3 overheated and shutdown mid flight whilst running in navigation mode. The iPad was mounted on my knee in portrait mode and shutdown approx 50 minutes into a return flight from Abberville in France to the UK. Although the cockpit temperature was not uncomfortable, the device was in direct sunlight under the perspex canopy of a DA40. I was wondering if the IPad app is rather processor hungry whilst operating in GPS mode? I intend to reduce the brightness of the display and turn off the 3g funtionality on the next flight to see if that aids the problem.