Aviation
Aircraft, flight mechanics, aviation history, and aerospace
Why Perpetual Solar Flight Is Hard: The Aerodynamics and Energy Budget
A solar aircraft that never lands has to win two fights at once: aerodynamic efficiency (how little power it takes to stay level) and the energy budget (storing enough daytime sun to fly through the night). This is why the real 'forever-flying' machines are rigid, ultra-slender wings flying at ~20 km altitude, and why a paraglider-style canopy is one of the worst possible shapes for the job.
High-Altitude Pseudo-Satellites: The Forever-Flying Platforms That Already Exist
The 'forever-flying device' people imagine already exists as a small family of stratospheric platforms — solar HAPS aircraft, stratospheric balloons, and airships — that loiter for weeks to months at around 20 km, offering satellite-like observation and communications from much closer to the ground.
High-Altitude Platform Station
A high-altitude platform station (HAPS), or high-altitude pseudo-satellite, is a long-endurance aircraft or balloon that loiters in the stratosphere at roughly 20 km to provide satellite-like communications and observation from far closer to the ground than orbit.
Solar-Powered Aircraft
A solar-powered aircraft uses photovoltaic cells to fly on sunlight, charging batteries by day to continue through the night. The core challenge of perpetual flight is storing enough night-time energy without making the aircraft too heavy to fly, which favours ultra-light high-altitude designs.
Airbus Zephyr
The Airbus Zephyr is a solar-powered, unmanned high-altitude pseudo-satellite with a 25 m wingspan that recharges batteries by day to fly through the night. In 2022 it set an endurance record of 64 days aloft.
Pathfinder 1
Pathfinder 1 is a modern rigid airship built by LTA Research and backed by Google co-founder Sergey Brin. Lifted in 2023 and first flown untethered in 2024, it is the largest aircraft in the world and the first big rigid airship to fly since 1939.
BAE Systems PHASA-35
The PHASA-35 is a British solar-powered high-altitude pseudo-satellite with a 35 m wingspan, developed by BAE Systems and Prismatic. It made its first stratospheric flight in 2023, reaching about 66,000 ft and landing ready to fly again days later.
Why Water Landings Are Dangerous: The Miracle on the Hudson Physics
Water at aircraft speeds behaves like concrete. The Hudson miracle required perfectly flat, tail-first contact at minimum speed — a few degrees off means the aircraft breaks apart on impact.
Why the Sky Isn't Full of Forever-Flying Machines: A Market Problem Dressed as an Engineering One
Persistent stratospheric platforms aren't a hard engineering problem anymore — solar HAPS, balloons, and airships all work. The reason the sky isn't full of them is that satellites quietly captured almost every job they could have done, leaving aerial platforms only niche, military, and regional roles, while helium cost, regulation, and the genuine hazards of busy airspace cap the rest.