The Exception to the Green Propulsion Rule

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By Bjorn Fehrm

November 30, 2023, © Leeham News: The interest in Green alternative propulsion for airliners started in earnest at Farnborough Air Show 2014, where Airbus flew the E-Fan battery-electric aircraft. What followed was a dense stream of alternative propulsion airliner projects.

They all have in common that nothing much has come out of them. We have a Pipistrel two-seat trainer that can fly for 50 minutes on batteries, but not much else. More elaborate projects have wide slips in their plans, and nine years later, we lack real prototypes for all projects.

We have functional models flying for nine-seat hybrids and 19/30-seat hydrogen fuel cell aircraft that swap one engine for a Green alternative. Of the latter, there is one project that stands out from the rest. It has shown real progress over the last years and has realistic plans for a 55-seat hydrogen airliner that can be operational in three to four years.

We will analyze why the Universal Hydrogen ATR fuel cell project is the exception to the “Green Propulsion Rule,” that nothing comes out of all plans, and why it could be the first Green Propulsion airliner, ending a 10-year draught.

Figure 1. The Universal Hydrogen Dash 8-300 functional demonstrator. Source: Universal Hydrogen.

Summary:
  • A Green Propulsion project means the airliner does not use hydrocarbon-burning (Kerosene or SAF) gas turbines.
  • The project that breaks the rule that nothing seems to reach practical use this side of 2030 is the Universal Hydrogen ATR project.

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Bjorn’s Corner: New aircraft technologies. Part 29. Detailed design

By Bjorn Fehrm

September 8, 2023, ©. Leeham News: We described the Preliminary design phase of an airliner development program over the last weeks. Now our project is transitioning into Detailed design.

It’s the most challenging part of the project as we now go from perhaps a thousand people involved at the OEM into tens of thousands and even more people at consultancies and suppliers.

 

Figure 1. A new airliner family development plan. Source: Leeham Co.

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The reality behind the eVTOL industry’s hyperbole, Part 7.

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By Bjorn Fehrm

August 24, 2023, © Leeham News: We have looked at the promises the VTOL industry made in their Investor prospects and what the reality is as the VTOLs come closer to Certification and production.

We started by using Joby and Archer as examples; now, we wrap the series by looking at some other top VTOL OEMs and how their claims have changed as the projects come closer to reality.

Figure 1. The Lilium jet VTOL. Source: Lilium.

Summary:
  • Joby Aviation and Archer are not alone in backpedaling on promised performance as certification nears; other OEMs that are investor-financed have the same problem.
  • In summary, the VTOLs in the first generation can only fly short-range missions. Longer flights run into energy reserve and cost problems.

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Bjorn’s Corner: New aircraft technologies. Part 25. Efficient development

August 11, 2023, ©. Leeham News: We have described a number of technological advances that can be used to make the next-generation airliners more efficient and, thus, more environmentally friendly.

Part of developing more efficient next-generation aircraft is to change the development process to be more efficient. The last Boeing aircraft, the 787, took 7.5 years from launch to entry into service, and Airbus A350 took 8.5 years.

The target is to reduce this by up to 50%, but how?

Figure 1. The Airbus A350 development schedule. Source: Airbus.

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The reality behind the eVTOL industry’s hyperbole, Part 4.

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By Bjorn Fehrm

August 3, 2023, © Leeham News: We look at the promises that the VTOL industry has made in their Investor prospects and the reality as they come closer to Certification and Production.

After looking at claims of range and utility, we now look at the operating economics. To do that, we need to predict the net sales price of these machines. We use our Aircraft Performance and Cost Model (APCM) to predict the production cost over time and, thus, the needed net sale price of the VTOLs.

Figure 1. The Archer Aviation Midnight VTOL mockup at the Paris Air show. Source: Leeham Co.

Summary:
  • The VTOLs are big; the Archer Midnight is the size of a nine-seater commuter aircraft (Figure 1). Aircraft costs are related to size and weight.
  • VTOLs use aeronautical production methods and supply chains for parts and systems. The production costs are, therefore, predictable.

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The reality behind the eVTOL industry’s hyperbole, Part 3.

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By Bjorn Fehrm

July 27, 2023, © Leeham News: We look at the promises that the VTOL industry has made in their Investor prospects and what the reality is as they come closer to Certification and present their production-level prototypes. We also analyze whether these capabilities will be the final level.

Today we go through the trickiest part of any electric aircraft or eVTOL, the batteries. They are large, very heavy, and the most difficult part to certify on the aircraft, as the battery is dangerous if not designed, produced, and managed correctly.

Figure 1. The Joby Aviation S4 production prototype. Source: Joby Aviation.

Summary:
  • The battery system of an eVTOL sets restrictions on the operational usefulness of the category.
  • The everyday operational utility of VTOLs is far from the industries’ claims.

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The reality behind the eVTOL industry’s hyperbole, Part 2.

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By Bjorn Fehrm

July 20, 2023, © Leeham News: We look at the promises that VTOL OEMs made in their Investor prospects and the scale-down in capabilities as Certification comes closer. We also analyze whether the reduced capabilities will be the final cuts.

In the end, it’s about how operationally useful real-world eVTOL will be and what mission they do better or cheaper than helicopters. It will decide whether the category will have a breakthrough or not.

Figure 1. The Joby Aviation S4 production prototype. Source: Joby Aviation.

Summary:
  • The Investor’s presentations from eVTOL OEMs are full of “up to” for speeds and feeds.
  • When we use our aircraft and eVTOL performance model, the reality is well short of the claims.

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Bjorn’s Corner: New aircraft technologies. Part 20. Efficient flying

By Bjorn Fehrm

July 7, 2023, ©. Leeham News: We explore different technologies in the series that can make our next-generation airliners more efficient and, thus, less polluting.

We have discussed developments of engine and airframe technologies, such as Turbofans versus Open Rotors and different airframe configurations to minimize drag and, thus, energy consumption.

When utilizing these developments to increase efficiency we must fly the aircraft in a different way depending on the technology.

And how we fly the aircraft is not only influenced by the factors we have discussed. We must consider factors at the airplane level, at the airliner operational level, and finally, at the airline fleet level.

Figure 1. The NMA concepts included dual aisle airliners. Source: Leeham Co.

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The Small Airliner Problem, Part 10. Cash costs for a battery-based airliner

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By Bjorn Fehrm

July 6, 2023, © Leeham News: In our series on costs factors that make up Cash Operating Cost for a battery-based airliner with range extenders, we now add Crew costs and Airport/Airway fees.

We then have all the components of the Cash Operating Cost (COC) for the ES-30 and can compare it to a normal propulsion 30-seat turboprop.

Figure 1. The Heart Aerospace ES-30 hybrid 30-seat airliner. Source: Heart Aerospace.

Summary:
  • The high operating weight and slow speed of a battery airliner increase the Airport/Airway fees and Crew costs for the ES-30.
  • In summary, only one Cash cost remains competitive, and the COC total exceeds the cost of a 30-seater turboprop.

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The Small Airliner Problem, Part 9. Maintenance costs for battery airliners with range extenders

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By Bjorn Fehrm

June 29, 2023, © Leeham News: In our series on fundamental costs factors that make up Cash Operating Cost, COC (Fuel, Maintenance, Airway/Airport fees, Crew costs) for new Green airliners, we have analyzed the energy costs and now move on to the maintenance costs.

For a battery-based airliner with range extenders, it’s a complex mix of battery and gas turbine costs.

Figure 1. The Heart Aerospace ES-30 hybrid 30-seat airliner. Source: Heart Aerospace.

Summary:
  • The maintenance costs for a battery-based airliner are high. It’s the batteries that cost, not the electric motors.
  • Adding range extenders complicates the propulsion system and adds further costs.

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