Massive Stratolaunch nears completion

Paul G. Allen, co-founder of Microsoft, sports team owner, entrepreneur and all-around philanthropist, made some news earlier this week when he posted on his LinkedIn page a statement titled, "Tackling the Space Challenge." In it, he describes growing up in the 1960s, fascinated with the idea of space and space exploration. He also bemoans the fact that, 50 years later, it is still expensive and difficult to propel even modestly size satellites into low-Earth orbit (LEO). 

This difficulty, he says, led him to found Vulcan Aerospace (Mojave, California), which, with Scaled Composites (Mojave), is producing the Stratolaunch, a massive carrier aircraft that will deliver a launch vehicle (rocket) to a high altitude, from where the rocket will detach, carry and deliver its payload to LEO. 

The carbon fiber composites-intensive Stratolaunch, at 75.5m/238 ft long, will check in with a wingspan of 117m/385 ft which, by that measure, will make it the largest aircraft ever to fly. It will be powered by six Pratt & Witney PW4056 jet engines scavenged from two used Boeing 747 aircraft. It will, says Allen, have a payload capacity of 550,000 lb/249,475 kg and a range of 1,000 nautical miles. 

The Stratolaunch was supposed to fly for the first time in 2016, and Allen promises in his LinkedIn message that it will soon roll out of its hangar. Launch vehicle status seems more uncertain. Vulcan first partnered with SpaceX on rocket development, but the two companies decided to part ways. Orbial ATK did some rocket development work after that, but that relationship also dissolved. According Wikipedia, Aerojet Rocketdyne (Rancho Cordova, California) is currently developing a dual-motor liquid fuel engine for the rocket.