The world's biggest plane, with wings longer than a football field, flies with a fueled-up hypersonic vehicle for the first time

• The world's biggest plane has just reached another milestone. 
• Stratolaunch's carrier took a fully-fueled Talon-A hypersonic vehicle on a three-hour-long flight. 
• This a "significant" step towards the company's first hypersonic flight. 

The world's biggest plane broke another milestone after it flew with a fully-fueled hypersonic vehicle prototype for the first time.

Stratolaunch's Roc took to the air on Saturday carrying its TA-1 Talon-A hypersonic vehicle, fuelled with live propellant. This was a "significant step" forward in Talon-A's development, the company said in a statement.

"While we have conducted several successful ground tests fueling and igniting the system, we needed to evaluate how the system performs in the flight environment prior to release," said Zachary Krevor, chief executive for Stratolaunch.

The company plans to eventually use Talon-A to help the US military test components at hypersonic speeds, according to The Defense Post.

Initial results from Saturday's flight, which lasted three hours and 22 minutes, showed the Talon-A's propulsion system "performed as predicted" while fully formed during the flight.

This marks the company's 12th flight in total, the latest since it performed its first drop test in May.

The company will review the data before determining the next steps but stated it aims to conduct a fully powered test flight of the Talon-A vehicle in the "near term."

Roc is Stratolaunch's carrier system, a mothership designed to bring heavy payloads like planes and rockets to the air. With its 385-foot-wide wingspan and six Boeing 747 engines, it can carry up to 500,000 pounds under its wings.

While there have been planes with bigger wingspans, Roc takes the record in terms of biggest all-composite plane ever constructed.

First founded by the late Paul Allen, cofounder of Microsoft, in 2011, Stratolaunch initially aimed to use Roc to air-launch rockets from high up in the atmosphere, much like Virgin Galactic.

But after Allen died in 2019, the company focused its efforts on hypersonic research, developing vehicles that aim to fly at least five times faster than the speed of sound, per Space.com.

The company has also teased the development of other lines of vehicles called Talon+ and Space Plane, though it has not released more information about the projects.