I was expecting to read that this was only the longest manned flight, but it seems that the record for unmanned/unrefueled flight via a solar-powered plane is a

I was expecting to read that this was only the longest manned flight, but it seems that the record for unmanned/unrefueled flight via a solar-powered plane is a bit less. That flight took place earlier this year and the drone vanished over the Arizona desert just hours before the record: https://simpleflying.com/airbus-zephyr-flight-ends/ https://simpleflying.com/airbus-zephyr-flight-ends/ . Clearly the government of Nevada contracted the aliens at Area 51 to ensure the integrity of their airport's tourist attraction.