What is the slowest fixed-wing airplane? It's easy to find information about the fastest airplanes, in different categories (e.g. X-15, SR-71, the Concorde etc), but what is the slowest one? Which powered, manned airplane is capable of sustained level flight at lowest velocity?
The Gossamer Albatross is a human-powered plane with a top speed of 29 km/h (18mph).



It was used to cross the English Channel and seems to meet the criteria of the question.