Microsoft co-founder Paul Allen would never be accused of not thinking big. And big is what his next project amounts to: launching unmanned rockets into space from a massive aircraft. Allen's new company, Stratolaunch Systems, said it will build huge aircraft with a wingspan of 385 feet, bigger than a football field and 70% longer than the wings on a Boeing 747, making it the largest aircraft ever flown. The plane will be built by Scaled Composites, the rocket will be built by Elon Musk's Space Exploration Technologies, and the state-of-the-art mating and integration system allowing the carrier aircraft to safely carry a booster weighing up to 490,000 pounds will be built by Dynetics. The first test flight is targeted for 2015.