Heart Aerospace, the ES-Thirty, and the Pivot from All-Electric to Hybrid That Admits Battery Technology Is Not There Yet

Heart Aerospace, the Gothenburg, Sweden-based aviation startup, raised tens of millions in airline investment and then publicly walked away from its flagship all-electric aircraft design. The replacement - the ES-30 - is a 30-seat hybrid-electric regional aircraft that still burns fuel, just far less of it. That pivot is both an engineering story and an honest reckoning with where battery technology actually stands today.

Why Heart Aerospace Abandoned the All-Electric ES-19

When founder Anders Forslund unveiled the concept in 2019, the ES-19 looked like the right aircraft at the right time. Nineteen seats, fully electric, no turbines. The target market was Scandinavia - Norway specifically, where short hops between fjord towns, aggressive carbon reduction mandates, and government appetite for clean aviation created an unusually favorable launch environment.

In 2021, United Airlines committed $35 million through its United Airlines Ventures arm, and Mesa Airlines signed on as a partner. For a startup without a flying prototype, that level of institutional confidence was significant.

Then, in 2022, Heart Aerospace canceled the ES-19.

The company ran the numbers on real-world battery energy density - which currently sits at roughly 250 to 300 watt-hours per kilogram for the best production cells available - and compared it to jet fuel’s approximately 12,000 watt-hours per kilogram. That roughly 40-to-1 ratio is the fundamental constraint every electric aviation startup faces. At nineteen-seat scale, the battery weight required to achieve useful range consumes so much payload capacity that the economics collapse entirely.

The honest answer was hybrid.

How the ES-30’s Hybrid Propulsion System Works

The ES-30 uses four electric motors driving conventional propellers in a twin-engine layout. Those motors are backed by a turbogenerator - a small turbine engine whose sole purpose is generating electricity rather than driving a shaft directly. The aircraft burns fuel to produce electrons; the electrons drive the motors. It is not a conventional turboprop.

The battery pack handles takeoff and initial climb, where electric motors genuinely excel. They deliver maximum torque from zero RPM with no spool-up time. The turbogenerator handles cruise on longer routes and serves as a range extender when battery capacity alone cannot complete the mission safely.

Crucially, the turbogenerator does not run on every flight. On short enough routes, the ES-30 is designed to operate entirely on battery power.

Range Figures and the Routes They Cover

The ES-30’s performance breaks down by operating mode:

Battery-only range: approximately 200 kilometers (108 nautical miles), with adequate reserves
With turbogenerator: approximately 400 kilometers (216 nautical miles)
Maximum hybrid range: approximately 800 kilometers (430 nautical miles)

The European regional turboprop market - the ATR 42, the de Havilland Canada Dash 8, the SAAB 340 - operates most frequently on routes between 100 and 250 nautical miles. The ES-30 fits the core of that market, with battery-only operation covering the shortest and most frequent hops.

These are aircraft types that have been in service for decades. Their fundamental propulsion technology has not meaningfully changed since they were designed. Every flight burns turboprop fuel because no alternative exists. The ES-30 is designed to change that equation on exactly these routes.

What United’s Investment Actually Signals

United Airlines’ position deserves scrutiny beyond the headline number. The $35 million investment came alongside a conditional order for 200 aircraft, contingent on the ES-30 achieving certification and meeting its stated performance targets. United is not typically known for speculative early-stage bets.

United operates a significant number of short regional hops through its United Express affiliates - precisely the route category where the ES-30’s economics work best. An airline buying electricity at the gate on short routes, rather than jet fuel at every stop, gains meaningful cost stability in a market where margins are measured in fractions of a percent. Jet fuel prices spiked sharply in 2022 and have remained volatile. That unpredictability has real balance-sheet consequences for regional operators.

The Certification Path - and Why Hybrid Helps

Heart Aerospace is targeting FAA and EASA certification around 2028. Whether that timeline holds is a legitimate question; aviation certification schedules almost never hold exactly. The failure mode analysis for the hybrid propulsion architecture alone is a substantial engineering and documentation effort. Interface certification between the battery management system, turbogenerator controls, and conventional flight systems at transport category scale presents challenges that haven’t been fully resolved.

That said, the hybrid architecture actually simplifies the regulatory path compared to a clean-sheet all-electric design. The FAA has decades of experience certifying turbine engines. It is building real experience with electric motors through the eVTOL programs currently in process. Combining known certified elements in a new configuration is a different regulatory task than asking authorities to develop entirely new standards for a propulsion system they’ve never evaluated. 2030 or beyond should not surprise anyone as a more realistic type certificate date, but the foundational work is on firmer regulatory ground than a pure-electric alternative would be.

Why This Matters for Pilots and the Regional Aviation Market

Four Risks Worth Tracking

Battery technology pace. The ES-30’s economics improve materially if solid-state battery energy density advances on optimistic timelines. If it doesn’t, the aircraft still functions, but its competitive advantage over a modern turboprop narrows. Heart’s hybrid design is explicitly a hedge against this uncertainty - the aircraft works with current cell technology and improves as cells improve.

Certification resource constraints. The FAA’s engineering review capacity is stretched across the broader aerospace regulatory workload. Getting slot time, type inspection authorizations, and engineering attention are real-world bottlenecks that good engineering cannot fully control.

Airport infrastructure. The ES-30 requires charging capability at every airport it serves. Scandinavian airport operators have been actively building electrification infrastructure. At smaller regional airports in other markets, that buildout is still an open question. Heart does not control this dependency.

Competition. Hybrid-electric regional aviation is not a one-company race. ATR, Airbus, and Wright Electric have all studied the category. Established players with existing regulatory relationships and larger balance sheets could accelerate programs if the technology matures. First-mover advantages in aviation technology development can close faster than expected.

The Significance of the ES-19 Pivot

The decision to cancel the ES-19 publicly - after taking investor money, after United and Mesa signed on, after building a market narrative around a clean all-electric product - was not easy. Investors wanted their thesis validated. Airline partners wanted the aircraft they expected. The press wanted a clean progress story.

Walking away from that narrative to build something that could actually be certified, operated, and flown profitably on real routes is a meaningful signal about how Heart Aerospace approaches engineering. The distinction between genuine engineering and slide-deck engineering matters more than any single performance claim. The path to measurably reducing regional aviation emissions will not come from companies that optimize their press releases rather than their aircraft.

Regional aviation - 30-seat aircraft flying 150 nautical miles, day after day - is where electrification has its first real commercial opportunity to move the needle on aviation emissions at scale. Not urban air taxis. Not single-engine trainers in the pattern. Heart Aerospace, with its hybrid architecture and demonstrated willingness to correct course when the data demands it, is one of the more credible engineering bets on making that transition happen.

Key Takeaways

Heart Aerospace canceled the all-electric ES-19 in 2022 after determining that current battery energy density - roughly 40 times lower than jet fuel by weight - makes a viable 19-seat commercial electric aircraft economically impossible on any near-term timeline.
The replacement ES-30 is a 30-seat hybrid-electric aircraft using electric motors backed by a turbogenerator; on short enough routes it operates on battery power alone, burning no fuel.
United Airlines invested $35 million in 2021 with a conditional order for 200 aircraft, targeting the short-hop regional routes its United Express partners fly most frequently.
FAA and EASA certification is targeted for approximately 2028, though 2030 or later is a realistic expectation given the complexity of hybrid propulsion interface certification at transport category scale.
The hybrid architecture is deliberately designed as a hedge: it works with today’s battery technology and improves progressively as energy density advances, without betting the program on a specific breakthrough arriving by a specific date.