Helios Horizon made aviation history Friday with the first flight of a human-piloted electric airplane powered by solid-state batteries, which can double the range and flight times possible with conventional electric-vehicle batteries.
One 5 June, Chief Test Pilot Miguel Iturmendi completed a series of initial test flights at Zephyrhills Municipal Airport in his world-record-setting Helios Horizon electric airplane, which has been reconfigured to use solid-state batteries to drive its single motor.
Unlike the lithium-ion cells previously used in Helios Horizon that power almost all electric vehicles today, solid-state batteries are smaller, offer 60%-80% greater energy density, and can be charged from almost empty to 80% in less than 15 minutes.
“For the first time, we have a battery technology that yields the range and charging times necessary to make commercial electric aviation viable, while providing the safety the flying public will demand,” Iturmendi said.
Unlike traditional cells, solid-state batteries are much more stable when subjected to high temperatures or even punctures, drastically reducing the risk of combustion.
Helios Horizon holds the world altitude record for an electric aircraft in its weight class and has been designed to fly into the stratosphere. While it has reached 24,000 feet on previous flights, the team is targeting altitudes over 40,000 feet — higher than most passenger airliners.
With the introduction of solid-state batteries into Helios Horizon’s unique power management and propulsion systems, Iturmendi expects to easily complete stratospheric flights on a single charge.
Helios Horizon’s previous lithium-ion batteries provided 260 watt-hours per kilogram, but its new solid-state batteries yield 410 Wh/kg. And Iturmendi expects solid-state batteries to increase in energy density by another 40% within two years. Their smaller volume and different discharge characteristics also positively impact aircraft range, altitude, and flight time.
Helios Horizon can charge its solid-state batteries using almost any AC electrical source, without any special infrastructure. It can also recharge in flight, via its solar panels and by using its propeller as a wind turbine when it isn’t needed for thrust.
“Regenerative flying, in which we glide and windmill the propeller during descents, can significantly increase the range of the airplane,” Iturmendi said.
Friday’s short test flights successfully validated the weight and balance of Helios Horizon after incorporation of the new batteries. They also confirmed what extensive ground testing of the propulsion system had proven — that the new batteries yield better-than-expected performance over hours of sustained operation.
The team now plans to continue optimizing Helios Horizon’s systems for stratospheric flights planned for later in the year.
About solid-state battery technology
Most electric vehicles and electric aircraft today rely on lithium-ion batteries that contain a liquid electrolyte. Next-generation solid-state batteries replace some or all of that liquid with solid materials, reducing fire risk and allowing more energy to be stored in the same amount of space. In testing, solid-state batteries have shown greater resistance to damage, overheating, and thermal runaway than conventional lithium-ion batteries.
About Helios Horizon
Helios Horizon is an initiative to develop a stratospheric electric airplane to demonstrate that electrically powered aircraft can match or exceed the performance provided by internal combustion engines.
Founder and Chief Test Pilot Miguel Iturmendi designed the Helios Horizon aircraft around a Pipistrel Taurus airframe, into which the team installed unique systems for power delivery, battery management, propulsion and thermodynamic control. The airframe was also modified with wing extensions and solar panels. Helios Horizon is based in Sarasota, Florida.
All images credited to James Darcy
