The twin-fuselage aircraft, the baby of Microsoft co-founder Paul Allen, was pulled out of its Mojave Air and Space Port hangar in California to begin fueling tests — the first of many ground tests.
Stratolaunch is designed to release rockets that will carry satellites into space. It has a 385-foot wingspan, features six engines used by the Boeing 747, stands 50 feet tall and can carry more than 500,000 pounds of payload. It has those 28 wheels.