Leeham News and Analysis
There's more to real news than a news release.
Bjorn’s Corner: Sustainable Air Transport. Part 37. VTOL Flight Control.
By Bjorn Fehrm.
September 16, 2022, ©. Leeham News: We discussed one of the critical systems for an eVTOL over the last weeks, the battery system, its cells, and its management system.
Another critical system for a VTOL is its Flight Control System (the FCS).
Figure 1. The Honeywell UAM FBW (Fly By Wire) triple channel computer. Source: Honeywell.
Bjorn’s Corner: Sustainable Air Transport. Part 35. Lilium battery cells.
By Bjorn Fehrm
September 2, 2022, ©. Leeham News: This is a summary of the article Part 35P, Lilium battery cells.
It discusses the requirement the Lilium jet principle puts on its battery cells and how this is solved, both with a slightly different cell type and with some operational adaptations.
Figure 1. The final Lilium VTOL configuration with 30 jets. Source: Lilium.
Bjorn’s Corner: Sustainable Air Transport. Part 30. Lilium Jet VTOL.
By Bjorn Fehrm
July 28, 2022, ©. Leeham News: This week, we analyze the Lilium Jet VTOL.
It’s a vectored thrust design, but it’s different enough in its characteristics from the vectored thrust VTOLs we looked at in Part 28 (Joby S4 ..) to motivate a separate article.
Figure 1. The final Lilium Jet configuration transports six passengers plus a pilot. Note the changed number of wing jets (from 24 to 20). Source: Lilium.
Bjorn’s Corner: Sustainable Air Transport. Part 29. Lift + Cruise VTOLs.
By Bjorn Fehrm
July 22, 2022, ©. Leeham News: We analyzed vectored thrust VTOLs last week, like Joby Aviation’s Joby S4. Now we look at VTOLs that separate vertical and forward flight thrust generation into two different systems. Typical exponents are Wisk Aero Cora, Beta Technologies Alia-250, and Embraer’s EVE.
Figure 1. Wisk Aero Cora. Source: Wisk Aero.
Bjorn’s Corner: Sustainable Air Transport. Part 28. Vectored thrust VTOLs.
By Bjorn Fehrm
July 15, 2022, ©. Leeham News: We started the analysis of the market’s most prominent VTOLs with multicopters last week. Now we continue with vectored thrust VTOLs.
The most known exponent for vectored thrust VTOLs is Joby Aviation’s Joby S4 VTOL, Figure 1.
Figure 1. Joby S4. Source: Joby Aviation.
Bjorn’s Corner: Sustainable Air Transport. Part 4. Reality checks.
By Bjorn Fehrm
January 28, 2022, ©. Leeham News: Having discussed where investments would be the most efficient in alleviating our Greenhouse gas problems and identified the low-hanging fruit, we now look at new technology airplanes that can improve the situation.
We start with classical airliners, working our way from small types to the largest, then we discuss the impact of new transport forms like VTOLs for short-haul transportation.
As we will use the Leeham Aircraft Performance Model in some of the work, there will be extra articles (for this one, a Part 4P) which are Paywall, where we use the model to generate deeper data and understanding.
Figure 1. The Alice nine-seater drawings from Eviation’s Web. The present drawing (dark blue) differs from the mid-2021 drawing (light blue, on top). Source: Eviation and Leeham Co.
Bjorn’s Corner: Sustainable Air Transport. Part 4P. Reality checks, the deeper discussion.
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By Bjorn Fehrm
January 28, 2022, ©. Leeham News: This is a complementary article to the Part 4. Reality Checks article. It uses data from Leeham Company’s Aircraft Performance Model to develop the relationship between OEW (Operational Empty Weight) and MZFW (Maximum Zero Fuel Weight) compared with MTOW (Maximum Take-Off Weight) for 74 airliners in the model.
The article also discusses in more detail what’s the reasons behind large weight misses for new projects and how it’s handled.
Bjorn’s Corner: The challenges of airliner development. Part 34. Wrap-up.
By Bjorn Fehrm, Henry Tam, and Andrew Telesca.
December 17, 2021, ©. Leeham News: As we wrap up the series where we look at the monumental work you have to do to get a new aircraft type certified, we will discuss how we need several aircraft variants, addressing different markets, if we shall survive as an aircraft manufacturer.
All successful aircraft manufacturers produce and market a family of aircraft. If you stay with only one variant, you will find it hard to keep good people as the development work ends.
Figure 1. Beech 1900, a 19 seater aircraft developed from the Super King Air 200 with 9 seats. Source: Textron Aviation.
Bjorn’s Corner: The challenges of airliner development. Part 33. Multi-country Certification
By Bjorn Fehrm, Henry Tam and Andrew Telesca.
December 10, 2021, ©. Leeham News: Our aircraft has now achieved its first deliveries and is Entering Into Service (EIS) with our launch customer.
This covers one customer and one jurisdiction. As each country is sovereign in Airworthiness certification, we have work to do for each market we want to address.
Figure 1. A new 19 seater design, the Cessna 408 SkyCourier, started life as a cargo aircraft certified to US Part 23 standards. Here, the passenger version. Source: Cessna.
Bjorn’s Corner: The challenges of airliner development. Part 32. Aircraft delivery and EIS
By Bjorn Fehrm, Henry Tam, and Andrew Telesca
December 3, 2021, ©. Leeham News: Last week, we went through typical problems by the start of serial production, such as weight creep and traveled work.
Now we discuss the ins and outs of delivering the aircraft to the customer airline and how we support the aircraft’s entry into service.
Figure 1. A new 19 seater design, the Cessna SkyCourier. Source: Cessna.