Compilation of test flights.
Pathfinder Solar Plane preceeded Centurion. Pathfinder turned into Pathfinder+ by removing the original center panel and replacing it with a panel that was about 48 feet in length. Centurion turned into Helios Prototype, which turned into Helios and Helios with a fuel cell. The difference between Centurion and Helios prototype was removing the center panel and adding 2 new center panels. Helios flew with 5 pods and had a full solar array. The fuel cell version was made by removing the center pod and replacing it with the fuel cell pod. That is the one at the end of the video.