What's the world's largest airplane?

Howard Hughes' enormous H-4 Hercules may still hold the record for wingspan. But that doesn't mean there's not a bigger plane out there. See more flight pictures.
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The quest to understand flight has obsessed humanity since man first looked up and saw a bird soaring effortlessly across the sky. The quest to make everything bigger, better and faster has obsessed humanity since man first walked upright. Where the two obsessions meet we end up with some pretty incredible flying machines.

Achieving controllable flight has not been an easy endeavor. Or a quickly advancing one. As early as 400 B.C., innovators in China were using specially designed kites to test weather conditions [source: NASA]. More than 2,000 years later, the Montgolfier brothers flew the first hot air balloon, carrying a (presumably surprised) rooster, duck and sheep to an altitude of 6,000 feet (1,800 meters) for more than a mile [source: NASA].

The quest moved more quickly after that, with gliders, steam-powered flying machines and finally the Wright brothers' first biplane success unfolding over the next 120 years [source: NASA]. With a working, motorized airplane at last on record, man turned to his natural inclination and set about enlarging it. Howard Hughes' infamous H-4 Hercules seaplane (aka Spruce Goose), which took off for its one and only, 1-mile (1.6-kilometer) flight in 1947, still holds the record for wingspan at nearly 320 feet (97.5 meters) [source: Malone].

Another giant, the U.S. Air Force's C-5 Galaxy, introduced in 1968 and still around today, falls short of the H-4's wingspan, coming in at nearly 223 feet (68 meters), but has it beat on length: 247 feet 10 inches (75.5 meters) compared to the Goose's 218 feet 8 inches [source: Malone]. And the much-talked about Airbus A380, notoriously plagued by production problems but superlative to the nth degree, beats out the C-5 on wingspan (261 feet 10 inches or 79.8 meters) and the Spruce Goose on length (239 feet or 73 meters).

Still, the A380 is not the largest aircraft. It's not even that close.

In this article, we'll find out which plane has the distinction of "largest" and how that honor is typically determined. It's not easy to find universal criteria for ranking aircraft, but there is one way many experts can agree on: maximum takeoff weight.

And there is one plane that outshines all others in how much it can lift off the ground.