Paul Allen’s giant Stratolaunch plane gets closer to first flight with 80 mph taxi test

Stratolaunch plane
Mountains loom in the distance as Stratolaunch Systems’ twin-fuselage airplane is taken out for testing at California’s Mojave Air and Space Port. (Stratolaunch Photo via Twitter)

The world’s biggest airplane, built by Microsoft co-founder Paul Allen’s Stratolaunch Systems, is one step closer to making its first flight after buzzing down the runway at California’s Mojave Air and Space Port this week at speeds as fast as 80 mph.

Stratolaunch’s latest round of taxi tests checked off another item on the seven-year-old company’s to-do list in advance of flight testing. Those test flights are expected to lead to in-the-air rocket launches by as early as 2020.

Based on a development plan laid out this spring, future rounds of taxi tests should reach on-the-ground speeds of roughly 100 mph, and then 140 mph. A speed of 140 mph, or 120 knots, is roughly what it’ll take for takeoff of the twin-fuselage plane, which has a record-setting wingspan of 385 feet.

Stratolaunch and its executives hailed this week’s runway tests in a series of tweets:

The plane was built for Stratolaunch by Mojave-based Scaled Composites, the same company that built the carbon-composite SpaceShipOne rocket plane and its White Knight carrier airplane more than 15 years ago for the Allen-backed effort that won the $10 million Ansari X Prize for private spaceflight.

Stratolaunch’s air-launch system is a dramatically scaled-up version of SpaceShipOne, Virgin Galactic’s SpaceShipTwo, and Virgin Orbit’s LauncherOne system. The massive airplane — which has been nicknamed Roc after a mythical giant bird — is designed to drop and launch rockets from an altitude of 30,000 feet.

Such a system basically gives the rockets a head start on their path to orbit, and also makes it possible to launch payloads into any orbital inclination from any location within range of a suitably large runway. If the weather isn’t acceptable for launch at one location, Roc theoretically could fly to a more suitable location.

Stratolaunch has a wide assortment of launch vehicles on the drawing boards, ranging from Northrop Grumman’s tried-and-true Pegasus XL rocket, to a medium-size rocket nicknamed the Kraken, to a crew-worthy space plane known as Black Ice, to hypersonic testbed planes that the company calls Hyper-A and Hyper-Z.