The Gossamer Albatross was a human-powered aircraft built by American aeronautical engineer Paul B. MacCready. Constructed using a carbon fiber frame with polystyrene wings, the aircraft was powered using pedals to drive a large, two-bladed propeller. On June 12, 1979, amateur cyclist Bryan Allen successfully piloted it across the English Channel, completing the 22-mile (36-km) crossing in less than three hours and achieving a top speed of 18 mph (29 km/h). What was its average altitude? Discuss
Source: The Free Dictionary