The world's biggest plane is a step closer to its first flight, after passing another major milestone.
The 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).
The main purpose of the test was to put the aircraft’s ability to steer and stop through its paces.
A ground team from Stratolaunch Systems Corp monitored a number of systems, including steering, braking, anti-skid and telemetry.
All objectives of this test were achieved.
Since the first engine runs in September, the Stratolaunch team has performed a series of engine tests from a newly established Stratolaunch Mission Control Center (MCC) located at its facility at the Mojave Air and Space Port in California.
The MCC serves as the Seattle-based firm's hub for testing communications and will eventually be the centre of its aircraft and launch operations.
Once low-speed taxi tests have been safely completed, the company will begin the next phase of taxi testing, which will include increased speeds.
In addition to fuel testing, engineers began testing the flight control system.
So far, they have have exercised the full limits of motion and rate of deflection of the wings control surfaces and stabilisers.
Building up to this week’s engine tests, electrical, pneumatic, and fire detection systems were also given a once over.
Writing on the
Stratolaunch website, CEO Jean Floyd said: 'Engine testing was conducted with a build-up approach and consisted of three phases.
'First as a "dry motor", where we used an auxiliary power unit to charge the engine.
'Next, as a "wet motor" where we introduced fuel. 'Finally, each engine was started one at a time and allowed to idle.
'In these initial tests, each of the six engines operated as expected.'
Over the next few months, they plan to continue to test the aircraft’s engines at higher power levels and varying configurations