Leeham News and Analysis
There's more to real news than a news release.
The reality behind the eVTOL industry’s hyperbole
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By Bjorn Fehrm
July 13, 2023, © Leeham News: We have done a deep dive series on the cost problems experienced by small airliners and how these make life difficult for alternative propulsion projects.
The eVTOL industry also faces problems, but here it’s more its own overinflated promises that rub. It’s the subject of our next deep dive.
We look at what the top OEMs promised in the past and what the reality is as they come closer to Certification.
When it comes down to it, what missions can be flown and what cannot? Are the missions that can be flown enabling a new industry?
Figure 1. The Joby production prototype as presented on 28th June. Source: Joby Aviation.
Summary:
- Investor prospects promised Total Available Markets (TAMs) as large as $500billion with flights at up to 200 miles per hour to destinations hundreds of miles away
- The reality is more profane. None of these promises hold water.
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.
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.
Bjorn’s Corner: New aircraft technologies. Part 17. Airframe with lower induced drag
By Bjorn Fehrm
June 16, 2023, ©. Leeham News: This is a summary of the article Part 17P. Airframe with lower induced drag. The article analyzes Boeing 737 MAX 8-sized airliners with Truss Braced Wings versus wings with folding wingtips and the standard MAX 8 wing. We use our Aircraft Performance and Cost model to get the drag data and overall efficiency improvement for the concepts.
Figure 1. Boeing concepts of a next-generation airliner with Truss Braced Wing. Source: Boeing.
The Small Airliner Problem, Part 8. A battery-based airliner
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By Bjorn Fehrm
June 15, 2023, © Leeham News: In our series on fundamental costs factors that make up Cash Operating Cost, COC (Fuel, Maintenance, Airway/Airport fees, Crew costs), we have started analyzing if the size related cost factors also apply to green propulsion airliners and if the trends stay the same or change.
We use the Heart Aerospace ES-30 project as an example of a battery-based airliner with range extenders. Last week we developed the fundamental aero data for the aircraft with our Aircraft Performance and Cost model; now, we fly representative sectors and look at the energy and fuel consumptions compared to a similar-sized turboprop airliner.
Figure 1. The Heart Aerospace ES-30 hybrid 30-seat airliner. Source: Heart Aerospace.
Summary:
- There is a difference between what the theory says about aircraft range on batteries and how you have to fly in practice to keep battery costs down.
- The ES-30 has dual range-extending Turbogenerators. They get going more often and at a shorter range than advertised.
Bjorn’s Corner: New aircraft technologies. Part 16. Airframe with lower induced drag
By Bjorn Fehrm
June 9, 2023, ©. Leeham News: This is a summary of article Part 16P. Airframe with lower induced drag. It discusses the Truss Braced Wing type of airframe that increases the practical wing span of an aircraft and thus reduces induced drag.
Figure 1. Boeing concepts of a next-generation airliner with Truss Braced Wing. Source: Boeing.
Bjorn’s Corner: New aircraft technologies. Part 15. Airframe for lower Induced drag
By Bjorn Fehrm
June 1, 2023, ©. Leeham News: Last week, we examined ways to lower the dominant drag of an airliner, the air friction drag (Figure 1).
Now we look at the second largest drag component, the Induced drag, and how it can be reduced. We go through the fundamentals of the drag to understand how to affect it. Then we look at aircraft changes to reduce Induced drag and if these make sense on an overall aircraft efficiency level.
Figure 1. The drag components on a typical single-aisle airliner at cruise. Source: Leeham Co.
Bjorn’s Corner: New aircraft technologies. Part 14. Airframe for lower friction drag
By Bjorn Fehrm
May 26, 2023, ©. Leeham News: This is a summary of the article Part 14P. Airframe for lower friction drag. The article discusses in detail a Blended Wing Body (BWB) type airframe and how it reduces the wetted area and, thus, air friction drag compared to a conventional tube and wing airframe.
Figure 1. JetZero Z5 250 seat BWB jet concept. Source: JetZero.
Bjorn’s Corner: New aircraft technologies. Part 14P. Airframe for lower friction drag
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By Bjorn Fehrm
May 26, 2023, ©. Leeham News: This is a complementary article to Part 14. Airframe for lower friction drag. It discusses in detail the Blended Wing Body (BWB) type of airframe that shall reduce the airframe wetted area and thus air friction drag.
The Small Airliner Problem, Part 6
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By Bjorn Fehrm
May 25, 2023, © Leeham News: In our series about the viability of the business plans for small airliners (nine to 50 seats), we have covered the cost factors that make up the Cash Operating Cost, COC (Fuel, Maintenance, Airway/Airport fees, Crew costs).
We now compile the Cash Operating Cost for the aircraft on a typical sector and discuss the result.
Figure 1. The D238eco 40-seat airliner. Source: Deutsche Aircraft.
Summary:
- The Cash Operating Costs do not reduce in proportion to passenger numbers for a smaller airliner.
- As a consequence, a small airliner needs a higher load factor or yield to be viable.