The world’s largest plane could be completed before year’s end at the Mojave Air & Space Port in a new space race to launch satellites at lower cost. Stratolaunch Systems reports making significant progress on its mammoth craft funded by billionaire Paul Allen to launch satellite-carrying rockets into orbit. The aircraft – powered by six 747 engines and with a 385-foot wingspan – is 40 percent complete, said Chuck Beames, executive director of Stratolaunch. “They are working like crazy in Mojave,” said Beames, who spoke to the Business Journal in advance of his appearance at a Colorado space symposium this month. Stratolaunch was founded in 2011 by Allen as a lower cost, more convenient alternative to ground-launched rockets. But there is plenty of competition. It is up against Space Exploration Technolo-gies Corp., or Space X, the Hawthorne company founded by billionaire Elon Musk that has developed reusable rockets. Also, Virgin Galactic is developing the LauncherOne rocket in Long Beach to carry small payloads of up to 500 pounds into space, and Generation Orbit Launch Services, in Atlanta, is developing rockets that can be launched from a Gulfstream business jet. The Stratolaunch aircraft will carry a 55-foot Pegasus II rocket capable of taking payloads topping 10,000 pounds into low-earth orbit, or payloads of 4,400 pounds into higher orbit. Allen, the co-founder of Microsoft Corp., is funding Stratolaunch through his Vulcan Inc. investment firm. The company did not disclose its development costs. Three leading aerospace companies are subcontractors: Northrop Grumman subsidiary Scaled Composites, Orbital ATK Inc., and Dynetics Co. Scaled is building the aircraft while also constructing a suborbital space vehicle for Virgin Galactic. Orbital, a Dulles, Va. developer of satellites and launch vehicles, will supply the rocket. And Dynetics, a Huntsville, Ga. engineering and applied sciences firm, is the systems integrator. Testing of the aircraft – dubbed the Roc after a mythological giant bird of prey – will start with low-speed and high-speed taxiing at the space port, with the first flight expected no later than fall of 2016. “We are taking a cautious approach with testing,” Beames said. Testing of the rocket would likely happen in 2018. Stratolaunch, based in Huntsville, Ala., is a first step by Allen, whose wealth is estimated at $17.5 billion by Forbes magazine, to change how access to space is provided. Ground-based launches are done from only three U.S. locations – including Vandenberg Air Force Base, north of Santa Barbara. Consequently, satellite launches need to be scheduled three to five years in advance. And those launches can be delayed or scratched by weather, adding to a mission’s cost. Stratolaunch claims to have an advantage because its plane will take off in poor weather and different locations. But the aircraft will need airports with 12,000-foot runways capable of handling a fully-loaded 747 – about half the 1.2 million-pound weight of the Stratolaunch craft. Marco A. Caceres, senior analyst and director of space studies for aerospace research firm Teal Group, said Allen’s project is not cutting edge, but rather a larger version of a prior launch system using a commercial plane. Orbital ATK used a Lockheed L-1011 Tristar aircraft to launch the Pegasus rocket during an 18-year period ending in 2012. The program was phased out as the plane became obsolete and launch volume remained low. However, Stratolaunch comes around at a more cost-conscious time and with a new aircraft. Potential customers include universities, non-profits and companies offering satellite-based broadband communications. Caceres said the program has a real shot at success if it can offer a true lower cost launch vehicle. Ground-based launches range from as low as $10 million for satellites carried by the Russian Dnepr I rocket to as much as $300 million for the Delta IV rocket of the United Launch Alliance, a joint venture of Boeing Co. and Lockheed Martin Corp.