"The team performed medium-speed taxi testing at the Mojave Air & Space Port in October 2018. Ground speeds reached a maximum of 90 mph during the test series," Stratolaunch said via Twitter.
The aircraft is being built for Stratolaunch Systems by Scaled Composites to carry air-launch-to-orbit rockets. Its first launch demonstration is scheduled for 2019, according to published reports.
Previous year, Stratolaunch aircraft, the world's widest plane intended to take rockets to the stratosphere for launch, conducted first taxi tests on a runway in California.
Paul Allen, the billionaire co-founder of Microsoft, died of lymphoma on October 15. Allen co-founded Microsoft Corporation with Bill Gates in 1975. He was reported to be the 46th-richest person in the world.