The biggest airplane in the world by wingspan (385 feet, enough to reach through both goalposts on a football field with length to spare) just took another step toward first flight. Stratolaunch has completed the first phase of engine testing. For the first time, the gargantuan plane started its six Pratt & Whitney turbofan engines.
The Stratolaunch megaplane, built by Scaled Composites for Paul Allen's aerospace company Stratolaunch Systems and unveiled in May, is an enormous twin-fuselage aircraft designed to carry rockets up to altitude and drop them. The rockets will then ignite and carry satellites the rest of the way to orbit. It's a novel way of launching payloads to space that saves fuel by bringing the rocket up to high altitude before launch. Rival Virgin Galactic is working on a similar launch system, though Richard Branson's rocket-carrying aircraft is a modified 747.
The first phase of engine testing was carried out in three steps. The first was a "dry motor" test, where technicians hooked up the turbofans to auxiliary power and fired them up. "Wet motor" tests followed, where fuel was introduced to the system. Finally, Stratolaunch Systems started up the engines one at a time and allowed each to idle. The six engines operated as expected, according to the aerospace company.
A number of systems were tested to prepare for the first engine runs as well. Fuel system testing evaluated each of six fuel tanks to ensure proper seals and operation. The flight control system was also tested as control surfaces on the wings and stabilizers were moved through their full range of motion. Electrical, pneumatic, and fire detection systems on the immense aircraft were also successfully tested.
Stratolaunch Systems now plans to spend the next few months running the engines up to higher and higher power levels to complete engine testing, which will culminate with the first taxi test runs. It's hard to pin down a first flight date, as the number of systems that need to be checked and tested on an aircraft of this size is enormous. When Stratolaunch takes to the skies in the coming years, however, we will find out if the humongous bird can truly compete with the likes of traditional rocket launchers like SpaceX and United Launch Alliance.