Leeham News and Analysis
There's more to real news than a news release.
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.
Bjorn’s Corner: New aircraft technologies. Part 22. Engine characteristics.
By Bjorn Fehrm
July 21, 2023, ©. Leeham News: Developments in engines and airframe technologies require that future airliners are flown differently to maximize the technology benefit.
After looking at the consequences of new developments for the airframe, we now analyze what engine developments mean for how they will be sized and flown.
Figure 1. The RISE engine from CFM. Source: CFM.
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.
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.
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 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.
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.
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 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.