When the six Pratt & Whitney turbofans spooled up at 06:58 PDT on 13 April 2019, the aircraft that rolled down the runway at Mojave Air & Space Port was unlike anything the sky had ever seen. Stratolaunch’s “Roc,” conceived by the late Microsoft co-founder Paul Allen and built by his company Stratolaunch Systems, spanned 385 feet—longer than an American football field—making it the largest aircraft ever flown by wingspan. Its dual-fuselage, all-composite design and gross take-off weight of 1.3 million pounds were intended to serve as a flying launch platform, carrying rockets to altitude for satellite deployment. The 2.5-hour maiden flight reached 17,000 feet and 189 mph, validating Allen’s vision of “airline-style access to space.” Though Allen had passed away six months earlier, his sister Jody Allen watched from the ground, noting that “Paul would have been proud.” Roc broke the record set by Howard Hughes’s H-4 Hercules, which had made a single brief hop in 1947. It stands as a monument to what private wealth, engineering audacity, and a passion for aerospace can build when government ledgers are not the only source of gravity.