Paul Allen's rocket-launching plane is the biggest in the world - here is how it stacks up to other great flying machines

The Stratolaunch plane is now the biggest in the world. Owned by Microsoft cofounder Paul Allen, its 385-foot wingspan bests the next biggest, Ukraine's Antonov An-225 at 290 feet.

The 500,000-pound aircraft is 238 feet long, 50 feet tall, and rolls on 28 wheels. It's powered by six engines.

Stratolaunch plans to use the aircraft as a platform to launch rockets into orbit. It may one day be able to deliver as many as three rockets into orbit on a single mission. According to Stratolaunch, the aircraft is on track to perform its first launch demonstration in 2019.

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