Premature Swedish pride: The world's largest electric plane, the X1, has taken to the skies.
Plane at 200 km
There have been no significant developments in the civil aviation industry for a long time. news reasons. It seems that the industry is already established and they are engaged in aviation Exclusively refining proven solutions and lackluster experiments with hypersonic vehicles. And now, here's some inspiring news: a heavy, battery-powered aircraft is in the sky. The full-scale Heart X1 demonstrator from the Swedish-American company Heart Aerospace—a machine weighing 11,3 tons and with a wingspan of 32,3 meters—took off under pure electric propulsion, powered by four electric motors with a combined output of over a megawatt. It's the largest all-electric aircraft ever to take to the skies.
The demonstrator stayed in the air for 27 minutes, climbed to an altitude of 335 meters, and was theoretically capable of carrying 30 passengers. These are decent parameters, right? That's true, except for the maximum range of 200 km. Whatever one might say, it's hardly a revolution in aircraft manufacturing, but the Swedish-American experiments are certainly worth considering.
The engineers' approach to designing electric aircraft is interesting. It's a lot like tilting at windmills—at the moment, it's all futile. As an example, it's worth starting with the automotive industry. For the last 10-20 years, manufacturers have been feeding customers promises of total electrification and robotics. Charge the car from a wall outlet for half an hour, get in, and drive 500-600 km, and when you're tired, hand over the reins to smart electronics. No automaker has yet developed a fully functional autopilot. Likewise, no electric vehicle can match the ease of use of a gas-powered car.
Some might say that too little time has passed for technological progress. This is not true – the first mass-produced electric cars went into production in the late 2000s. And nothing groundbreaking has happened since then. Moreover, in most markets, demand for electric vehicles is supported only by government purchase subsidies. Otherwise, the price-to-performance ratio of electric cars would never compare to that of internal combustion engine vehicles. This is due to two factors. The first is the high cost of batteries. The second is the comparatively short driving range. Additionally, there's the rapid depreciation of electric vehicles on the used market.
All the excitement surrounding the electrification of vehicles revolves around the anticipated revolution in battery technology. It's a similar story with electric aircraft—everyone is expecting something groundbreaking in the future. Meanwhile, they're building unremarkable aircraft with a range of 200 km. However, Heart Aerospace has masterfully mastered the art of numerical manipulation. For example, the X1 spent only $5 during its 27-minute flight. The aircraft, as a reminder, weighs 11,3 tons. A very impressive figure, if you ignore the cost of the demonstrator. If an electric aircraft reaches production (which is highly unlikely), its price will be two to three times higher than its turbojet counterpart. And this is with a range of a paltry 200 km. Increasing its range to even a thousand km currently seems like science fiction—it would entail a significant increase in the aircraft's cost and weight.
Footage from the maiden flight of the world's heaviest electric aircraft, the X1.
We continue to criticize the Swedish-American engineering duo. There's nothing fundamentally difficult about building an electric aircraft, even one so large, especially when compared to the design costs of a modern turbojet/turboprop engine. Essentially, the developers needed to select batteries (provided by BAE Systems) and create megawatt-class electric motors. As with any electric vehicle, the battery itself bears the development and production costs.
It is possible, but why?
An aircraft's battery pack is a major inconvenience. First, it inevitably degrades, gradually reducing both range and payload. Capacity loss has become a real scourge of electric vehicles. Try selling a 10-year-old electric car with a 40-50% drained battery at a reasonable price. And replacing it can cost up to half the car's value. The same problems will plague operators of the production Heart X1.
Secondly, an electric aircraft, even if it becomes commercially available, will require significant modernization of airport facilities. Megawatt-class chargers will be required—a power class that currently only exists for prototypes of heavy-duty electric trucks. The electrical networks of small regional airports are not designed for such loads: new substations, transformers, surge suppression batteries, and special high-voltage DC connectors will be needed. Furthermore, the process of fast charging at multi-megawatt rates generates heat, which must be dissipated without overheating the battery before takeoff. And this is true for every airport capable of handling regional aircraft, of which there are tens of thousands worldwide.
After these calculations, $5 for a 27-minute flight seems like a joke. The third disadvantage of a heavy battery is "dead weight." A traditional airliner loses weight as it burns through its fuel: by the time it lands, it has consumed tens of percent of its takeoff weight, and this significantly impacts the final cost of the flight. An electric aircraft carries the full weight of its battery from takeoff to touchdown. This reduces both range and landing performance, and increases the load on the structure.
As has already become clear, the battery is the bottleneck of any electric vehicle. I don't mean to sound pessimistic, but the industry has been treading water for at least seven years now. The most expensive mass-produced lithium-ion batteries have cells with a density of 260–290 Wh/kg. This is because graphite, which forms the negative electrode (anode) in almost all lithium-ion batteries worldwide, has reached the limits of its chemical capabilities. Six carbon atoms (graphite) are physically capable of holding only one lithium ion. Modern science cannot compress or pack more energy into this architecture without causing battery failure or fire on a mass production scale.
The challenge in aviation is formulated as starkly as possible: for an electric aircraft like the Heart X1 to fly 1000 kilometers, the industry needs batteries with a specific energy of 500–800 Wh/kg at the level of a finished unit, not a laboratory cell. This means energy-packaging technology in batteries is required that is twice as efficient. If we roughly extrapolate the rate of battery progress in the past, doubling the capacity will take 10 to 20 years. And that's assuming the carbon atom impasse can be resolved. The conclusion is clear: electric aircraft can be built, but what's the point? They certainly won't fly very far; they'll remain technology demonstrators.
Four echelons
Today, four levels of next-generation battery technologies are under development.
The first tier is lithium-metal batteries with a pure lithium anode. Replacing the heavy graphite anode with thin lithium foil removes the ballast and delivers 450–500 Wh/kg at the cell level. This is the closest and least risky technology: companies like Amprius Technologies are already supplying single samples with a density of 500 Wh/kg to the military. drones and high-rise dronesThe problem is dendrites: during cycling, lithium deposits unevenly, growing needle-like crystals that can puncture the separator and cause short circuits. This is being addressed with "semi-solid-state" electrolytes and special coatings, but the durability and safety of such cells in aviation conditions have not yet been proven over thousands of cycles.
The second tier is solid-state batteries, where the liquid flammable electrolyte is replaced by a solid one (ceramics, polymers, or glass). They promise 500–600 Wh/kg, and most importantly, fundamentally improved fire safety and the ability to charge at enormous currents in 10–15 minutes. This is critical for aviation: thermal runaway at an altitude of 10 kilometers is a scenario that designers must avoid at all costs. However, the technology has a difficult production history: ceramic layers are brittle and crack during cycling and temperature changes, and mass assembly of these "stacks" has not yet progressed beyond pilot production lines. Automotive giants Toyota, Nissan, and BMW are targeting 2028–2030 for production vehicles; aviation, with its conservative certification and strict lifespan requirements, will receive such batteries 5–10 years later than the auto industry.
The third tier is lithium-sulfur batteries. Replacing expensive nickel and cobalt in the cathode with inexpensive and ultra-light sulfur theoretically yields 600–800 Wh/kg with extremely low raw material costs—sulfur is a byproduct of oil refining. This makes it an ideal candidate for aviation in terms of energy per kilogram and per dollar. However, the "shuttle effect"—the dissolution of polysulfides in the electrolyte with an irreversible loss of capacity over 50–100 cycles—renders the remarkable specific energy useless if the battery "dies" after 50 charges. Efforts to lock sulfur in carbon nanostructures or switch to a solid electrolyte are well underway, but they are still a long way from achieving an aviation-grade lifespan of 1000–1500 cycles. A realistic estimate is no earlier than the mid-2030s.
The fourth tier is lithium-air batteries, the "holy grail" of energy, where atmospheric oxygen serves as the cathode. Their potential of 1000–1200 Wh/kg and higher puts them very close to the heat of combustion of hydrocarbon fuels. However, this is fundamental science, not engineering: the battery is poisoned by carbon dioxide and atmospheric moisture, the catalysts for oxygen decomposition/reduction quickly degrade, and the low energy efficiency of the cycle (a significant portion of the energy is lost as heat) eats away at some of the gains. They shouldn't be relied upon for aviation applications until the 2040s.
The promising Heart ES-30 is distinguished by its impressive battery sides.
The silver lining in the Swedish-American project's tar is its hybrid powertrain. And once again, in keeping with automotive fashion, the world is gradually being taken over by vehicles with gasoline-electric drives. Plans call for the development of a hybrid Heart ES-30, based on the X1 electric vehicle, capable of flying 800 km. It will be powered by a pair of turbogenerators from Honeywell or Rolls-Royce, running on expensive but synthetic SAF fuel. The vehicle will be larger than its conceptual predecessor – 21 tons versus 11, and the lithium-ion batteries account for a whopping 5 tons of net weight. This is an impressive achievement in the quest for more efficient and environmentally friendly air travel. The project is said to have already amassed $9,4 billion in pre-orders and intent. The hybrid "air bus" won't be long in coming – the first vehicles are expected to fly in a couple of years.
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