A giant six-engine aircraft with the world’s longest wingspan – surpassing Howard Hughes’ infamous Spruce Goose – took off from California on its first flight on Saturday. The behemoth, twin-fuselage Stratolaunch jet lifted off from Mojave Air and Space Port and climbed into the desert sky 70 miles north of Los Angeles. It landed two hours later. Stratolaunch Systems chief executive Jean Floyd said the aircraft made a “spectacular” landing. The company, founded by billionaire Microsoft co-founder Paul Allen, who…