Helios Horizon Flies Crewed Electric Plane Using Claimed Solid‑State Batteries

Overview

• Helios Horizon conducted a series of crewed test flights on June 5 that validated weight, balance, and sustained operation after swapping in cells the team describes as solid‑state.
• The project reports the new cells deliver about 410 watt‑hours per kilogram versus the prior 260 Wh/kg packs, which Helios Horizon says gives roughly 60–80% greater energy density.
• The team says the batteries can charge from nearly empty to 80% in under 15 minutes and can use ordinary AC power, plus in‑flight regeneration from solar panels and windmilling the propeller.
• Independent technical verification of the cell chemistry and published range or speed figures is not yet available, and some industry observers dispute whether the cells meet a strict definition of 'solid‑state.'
• Helios Horizon plans to attempt stratospheric flights later in 2026 targeting altitudes above 40,000 feet and says the new cells should allow single‑charge missions, a development that could materially change electric aviation endurance if confirmed.