Flying electric

Why fly electric?

Electric aircraft have zero emissions and offer a comfortable, quiet flight experience. The significantly reduced direct operating costs also enable electric aircraft to develop new routes, or restore legacy routes, that were not profitable with gas turbine powered aircraft. This offers a unique opportunity to improve regional air mobility and connectivity for everyone.

What will the onboard experience be like?

The ES-19 is much quieter than any fossil-fuel aircraft, and the engine vibrations that can be felt on smaller aircraft are virtually eliminated. The aircraft is fully fly-by-wire, and actively compensates for turbulence, ensuring a smoother ride in all weather conditions. The all-metal fuselage is fully pressurised.

Market

Is there really a market for 19-seater electric aircraft?

A few decades ago, 19-seater aircraft were very common. Since then, the large acquisition and maintenance cost of turboprop jet engines have made 19-seaters uneconomical. Whereas regional planes averaged at 20 seats in the 1980s, today they average 80 seats.

Why don’t airlines fly as many 19-seaters anymore?

When the engine cost-of-ownership can be the same for a 19-seater and a 70-seater, and engine wear is the same whether you fly a 100 km as a 1000 km route, flying short hops with small turboprop aircraft is simply not profitable to airlines. 

How does going electric change the economic equation?

Our electric motor is about 20 times less expensive than a similarly-size turboprop, and about a 100 times less expensive than the cheapest turbofan. More importantly, maintenance costs are more than 100 times lower. These lower operating costs will make 19-seater electric aircraft competitive to 70-seater turboprop aircraft. 

Will electric aircraft create increased demand for short-haul air travel?

Yes, electric aircraft could enable a mode shift, where routes that previously were driven by car can be done by air. These will be driven largely by the reduction in maintenance costs – airlines operate at very low profit margins, and a reduction in maintenance cost has a nonlinear effect on profitability.

How long distances can you cover?

Our first-generation aircraft will have a maximum range of up to 400 km (250 miles), which will increase as battery energy densities improve.

What about reserves?

Reserve, alternate, and contingency energy (fuel) requirements vary by geographical region, and by the type of operation being flown (VFR, IFR, etc). In addition, for short range operations, there are procedures for reduced contingency fuel, and for no alternate depending on the specific route.

However, as a general rule, a significant portion of the available energy on an electric aircraft needs to be reserved for missed approaches, adverse weather conditions, etc. Therefore, our early focus will be very short routes. This is not a problem – the unit economics of electric aircraft will be better the shorter the route, as the recharge times will be shorter, the battery wear will be less, and more departures can be made in a day.

What’s a typical route that the ES-19 will fly in 2026?

Our early adopter market will be very short flights where there is high demand. This will include island-hopping and flying over mountainous terrain, where the flight distance is significantly less than the road routes available.  

What are typical early routes in the US?

Examples of routes include Chicago O’Hare International Airport (ORD) to Purdue University Airport (LAF), which is 191 km, and San Francisco International Airport (SFO) to Modesto City-County Airport (MOD), which is 120 km.

What are typical routes in the Nordic countries?

Typical routes in the Nordic countries include Stockholm-Visby, Bergen-Stavanger, Skellefteå-Vaasa, Trondheim-Östersund, and Gothenburg-Copenhagen, as well as all domestic flights on Iceland and Greenland.

What are typical routes in the rest of the world?

We have seen large interest for domestic flights in Canada, New Zealand, the British Isles, and the Alps, but also from countries like Indonesia, a country of 17,000 islands that has undergone a four-fold increase in domestic air travel in the last decade.

 

The Environment

Why do we need to decarbonize air travel?

Air travel contributes to about 2% of global CO2 emissions, and emissions are growing exponentially at a rate of about 5% a year. Some analysts predict that by 2050, about 25% of global CO2 emissions will come from aviation alone. Fossil-fuel aircraft also emit NOx, soot, water vapour and other  greenhouse gases. According to recent studies, the overall effect of these emissions can be triple of those of CO2 alone.

Can we electrify all air travel?

While it’s impossible to predict the future, it is unlikely that we will be able to cross the Atlantic on battery-powered passenger planes any time soon. However, electric aircraft will play an important role in decarbonising short-haul air travel. 

Electric aircraft will have short range – isn’t the environmental benefit very limited?

About 4% of global emissions are from routes under 200 km, and 9% of global emissions are from routes under 400 km, which we believe can be electrified before the end of the decade. Our long term goal is to electrify all short-haul travel, i.e. all trips under 1300 km, by the year 2050. Today, these trips account for about 33% of global emissions. Changing the way we travel, using many small airports and allowing for more stopovers is another tool at our disposal. The total emissions from air travel is expected to rise to 2.8 Gigatons by 2050.

Is all-electric propulsion only viable for very small aircraft?

No, and this is a common misconception. The range of an electric aircraft is determined by the aerodynamics and the percentage of the aircraft weight that’s made up of batteries. For today’s jet aircraft, larger aircraft have better performance with regards to both aerodynamics and fuel-mass fraction, there is no reason to believe that this wouldn’t be the same for electric aircraft.

There are, however, more practical considerations as to why we start with a 19-seater aircraft. The certification process is easier, the technology overlap is largely similar to that of electric cars and buses (charging, motor design, etc), and it’s an overall less risky and expensive endeavour. However, we are planning for larger aircraft in the future.

Are there governmental incentives to electrify air travel?

Yes. Norway aims for all short-haul flights to be 100% electric by 2040, and Sweden wants all domestic travel to be fossil-fuel free by 2030.

What about CO2 created in electricity generation?

Electric aircraft work best in places with cheap access to renewable energy, just like electric cars. In Sweden and Norway, over 90% of grid energy comes from renewable sources. Moreover, many airports are using their land to install solar panels and wind turbines.

What about the CO2 emissions in manufacturing of the aircraft?

The carbon footprint of manufacturing and maintenance for our aircraft is several orders of magnitude lower than for other modes of transport. The high utilisation rates of electric planes gives them a much smaller manufacturing footprint than electric cars.

What about hydrogen, sustainable aviation fuels and other technologies?

Electric aircraft will not be viable for long-haul routes anytime soon, and therefore, it is only part of the solution for decarbonising air travel. Hydrogen and biofuels can be looked to for these applications.

However, what sets electric aircraft apart are the unit economics. Whereas biofuels today are much more expensive than fossil fuels, and hydrogen aircraft would require a whole new infrastructure and operations, electric aircraft present a major cost advantage to airlines. Further, the ubiquity of the electricity network makes it relatively easy for airports to install chargers.

Heart’s airliner

How many seats?

The ES-19 aircraft will have 19 seats, arranged in 8 rows of 1+1 arrangement, plus three seats at the rear. Seat pitch will be a comfortable 30” (76cm).

When can I buy my first flight?

The ES-19 will be certified in Q3 2026, and we expect entry into service later that same year.

What are the runway operational requirements?

The ES-19 is designed to be an electric STOL (Short Take-Off and Landing) aircraft  It is designed to operate from runways as short as 750m and will have steep approach capability.

Will the ES-19 be safe to fly?

The ES-19 will be certified to existing CS-23 certification standards, the same as used by all conventional aircraft. As a 19-seat passenger aircraft, we will certify to the highest level of CS-23, Level 4, with requirements as stringent as most commercial aircraft.

In addition, the ES-19 will be operated by approved airlines, flown by qualified pilots with a traditional air transport pilot licences, operate in the same existing airspace as all other commercial aircraft, and from conventional airports.

Development and company

2026 is not far off. How will you meet the deadline?

As a start-up, we must develop the company, the organisation and the product concurrently. To accomplish this we started our Design Organisation Approval process early in 2019, and are working with EASA to progress it. At the same time we have been hiring aerospace expertise from around the world to validate and progress the design of the aircraft. In total, since the company launch and early conceptual design, we have allowed more than 8 years to certify this product.

How does your roadmap look?

Our major milestones towards certification are to complete a Preliminary Design Review (PDR) in Q3 2022, a Critical Design Review (CDR) in Q3 2023, a first flight in Q4 2024, and a Type Certificate in Q3 2026. Entry into service would follow in Q4 2026.

Don’t we need to wait several decades for the technology to mature?

This is one of the most common misconceptions about electric aircraft, and it is wrong in two ways. Firstly – the technology is already here (We have already built full-scale demonstrators of the propulsion system). However, there is still a lot of work to design, certify and manufacture these aircraft. That is why we need to start now. Technological process does not occur automatically – it is the result of large investments and dedicated engineering work. 

What are the biggest technical challenges?

It is important in any aircraft development programme to limit the number of risk areas, and focus on them relentlessly. That is why many established manufacturers often do incremental developments of their products. The electric propulsion system is novel in this industry, and therefore is the most technically challenging aspect by definition. However, Heart Aerospace has chosen to minimize technical risks or challenges in almost all other aspects, which is why we have chosen a conventional high-wing, low speed aircraft, with traditional aluminium construction.

With most other aspects of the design being low-risk, we were able to target almost all of our seed funding on developing, testing and iterating the design of the propulsion system.

It is worth noting that the ES-19 will be operated by existing qualified pilots, in existing airspace, and from existing airport infrastructure.

Is the technology for electric planes different from that of electric cars?

We can, and have, learned a lot from the advances in the electric vehicle (EV) market. Several lessons have been learned there, and we do not need to re-discover them.

Perhaps the biggest difference between automotive and aerospace electric propulsion system development is the certification and qualification requirements for both hardware and software. Development Assurance requirements for airborne systems have unique requirements, including stringent safety analyses.

Building an aircraft is hard, and even large aerospace companies struggle. Can a startup build and certify an aircraft?

At its core, a company is nothing else than a collection of people working to solve a problem together. Although our company is new (formed in 2019), our employees have previous experience working at 100+ different aircraft projects, at companies such as Airbus, Boeing, Bombardier, Embraer and Mitsubishi.

Moreover, an aircraft is a lego kit of different components manufactured by different suppliers. Heart Aerospace is working with the same suppliers as the established aerospace companies.

Can an electric aircraft be certified?

EASA Special Condition (SC) E-19 has been published for certification of electric propulsion systems in CS-23 and CS-25 aircraft. Smaller commercial aircraft up to 19 passengers (such as the ES-19) are certified under CS-23 regulations, which have recently been rewritten to move away from prescriptive regulations to performance based rules. Compliance will  be based on industry consensus standards, which is a faster certification pathway. This rewrite allows the commercial aviation industry to introduce new technology that would have been more difficult under past regulations.

On this front Heart is helping to advise on certification and regulation requirements to the authorities (EASA and FAA). We are a voting member of ASTM, who are developing the consensus standards referenced by the new Part 23 certification framework.

The current industry standard and accepted means of compliance for certifying liquid electrolyte lithium-ion batteries is laid out in RTCA DO-311A. The test involves forcing 2 adjacent cells into thermal runaway, and showing it does not lead to a chain reaction thermal runaway, no release of fragments outside the battery system and no escape of gases outside the battery system except through designated venting.

Airports and charging

Do electric aircraft require expensive ground infrastructure?

We estimate the cost per charger for the ES-19 to be around $500k. A significant part of this infrastructure could be dual-purpose supporting the ground transportation and service vehicles.

Do electric aircraft require advances in charging technology?

No. The current and emerging generation of high power chargers developed for automotive applications support the voltage and power levels required for electric aircraft charging. The most notable difference for aircraft applications will be the physical connector type and perhaps the data communication between the charger and aircraft. The SAE is actively working on the connector and communications specification.

What is the charge time?

Charge time is largely dependent on the available charging infrastructure but with the recommended charging, we can charge an ES-19 in less than 40 minutes for an average mission.

What are the power requirements per charger?

We recommend an optimal charging power of 1MW per aircraft, to achieve the customer desired turnaround time. 

Charging can be accomplished by mobile chargers that connect directly to the grid power, fixed charger installations at specific gates, or even mobile storage units that may be charged remotely. It very much depends on the specific airport and flight operation frequency.

Batteries

Aren’t batteries expensive? Will an electric aircraft be unaffordable?

Heart’s ES-19 will have a similar acquisition price and offer direct operating costs (energy and maintenance) 50 – 70% lower than competing fossil fuel powered aircraft. In the full aircraft context, battery acquisition costs are less than 2% of the aircraft price. This is very different to road EV’s where batteries comprise about 30% of the car cost. Battery cycle amortisation costs are less than 10% of the ES-19s direct operating cost.

Battery costs have fallen by almost 10x since 2010. According to the latest forecast from research company BloombergNEF (BNEF), “Battery prices, which were above $1,100 per kilowatt-hour in 2010, have fallen 87% in real terms to $156/kWh in 2019. By 2023, average prices will be close to $100/kWh.” BNEF cites a longer term forecast of batteries costing $61/kWh by 2030.

How often do batteries need to be replaced?

In our direct operating costs-model, we assume 1000 cycles. This is a slight increase from the electric aircraft certified today – the Pipistrel Velis Electro – which has a cycle life of 800 cycles. However, we do think it’s achievable to reach 3000 cycles, or even more, depending on the specific route. Even so, if an aircraft is used ten times a day, batteries will need to be replaced on a yearly basis.

Do you allow battery swaps?

We believe the logistics of battery swaps add unnecessary complexity and cost to operations, and for our early use cases, we do not deem them necessary, as charge times will be fairly short. Battery swaps would be considered a maintenance action requiring a return-to-service test procedure, which would definitely be longer than the charge time possible with current charging technology.

What happens with the batteries afterwards?

Even after the batteries are no longer airworthy, they will still retain significant capacity, and there are therefore many second-life applications. A typical application could be to use the batteries for grid energy storage at airports.

At the end of the second-life application, companies such as Northvolt, provide end-of-life solutions where more than 50% of the materials can be recycled and reused.

How will batteries react to weather conditions? 

While aircraft can experience significant changes in outside temperatures, the battery packs will be actively conditioned to a specific operating temperature – just like most electric cars. However, unlike electric cars, there are generally no spontaneous or unscheduled use cases for an aircraft, where batteries don’t have time for being preconditioned, and are forced to operate at suboptimal temperatures. These use cases for cars lead to lower range and decreased cycle life. Aircraft batteries will operate in a much more controlled environment, and due to the large portion of the batteries that will only be used for reserves, they will rarely become fully discharged.

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