Paul Allen, who co-founded Microsoft with Bill Gates, unveiled the world’s largest aircraft in June
The six-engine plane has a wingspan of 385 feet which is longer than the length of a football field
Stratolaunch is designed to carry rockets between its two fuselages before they launch into space from air
Firm fired up the aircraft’s six Pratt & Whitney turbofan engines for its first taxi down the runway at 28mph
The world’s biggest plane is a step closer to its first flight, after passing another major milestone.
Named Stratolaunch, the colossal aircraft travelled down the runway under its own power for the first time, firing all six of its Pratt and Whitney turbofan engines – each weighing 8,940lbs (4,000kg).
During the aircraft’s first low-speed taxi test, Stratolaunch successfully travelled down the runway at 25 knots (28mph/45km/h).
Once testing has been completed, the aircraft – which has a wingspan longer than a football field – will be used to launch satellites and other objects into space.
This could include a Dream Chaser spaceship, which could act as a mini-shuttle to reach low Earth orbit destinations and return astronauts or payloads to a runway within 24 hours.