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 21. Changed flight profiles

By Bjorn Fehrm

July 14, 2023, ©. Leeham News: Developments in engines and airframe technologies require that the aircraft are flown differently to maximize the benefits.

We start by locking what changes in parasitic and induced drag mean for how airliners fly.

Figure 1. A Truss Braced Wing airliner shall fly higher. Source: Boeing.

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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.

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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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Bjorn’s Corner: New aircraft technologies. Part 19. Supersonic drag

By Bjorn Fehrm

June 30, 2023, ©. Leeham News: In our discussions about the drag of an airliner, we now cover the most complex drag type, Wave drag, or the drag created when the air goes from subsonic to supersonic flow.

We will focus on the physical understanding of what’s happening as the math behind the drag calculation is complex.

Figure 1. The Concord is designed for low Wave drag. Source: BAC and Aerospatiale.

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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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Bjorn’s Corner: New aircraft technologies. Part 18. Minor drags

By Bjorn Fehrm

June 23, 2023, ©. Leeham News: In our series about technologies that influence the efficiency of a new generation of airliners, we have covered the dominant drag of an airliner, air friction drag, and the second largest drag, induced drag, and what can be done about them. Now we look at Pressure drag and Interference drag.

We will finish with Transonic drag next week, which requires a full Corner to explain well.

Figure 1. The drag types that affect our airliners. Source: Leeham Co.

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What’s the Green aviation news at Paris 2023?

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By Bjorn Fehrm

June 22, 2023, © Leeham News: Every announcement from aircraft deals, OEM updates, or supply chain news now has the words Sustainable/Sustainability injected in every second sentence. It doesn’t matter what the subject is; if it’s about a gas-guzzling way of transporting people at supersonic or even hypersonic speeds or at the other end in an eVTOL which is only as fast as your car on a US highway.

What is the real news about making our air transport system less polluting behind this misuse of the buzzwords? You have to search behind the headlines and the announcements that you know will not turn the dial. Let’s tour the Paris Air Show 2023 and look at the real developments in Sustainability.

Figure 1. First flight of Universal Hydrogen’s DH8-300 with a hydrogen propulsion system on the starboard side. Source: Universal Hydrogen.

Summary:
  • The waves of Green propulsion solutions with inflated claims have calmed down.
  • It’s replaced with operationally usable solutions that deliver tangible emission gains.

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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.

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