Leeham News and Analysis
There's more to real news than a news release.
Bjorn’s Corner: The Blended Wing Body, BWB, Airliner. Part 1.
By Bjorn Fehrm
March 13, 2026, ©. Leeham News: The flying wing has been researched for almost 100 years. During the Second World War, the Horten Brothers developed as flying wing military aircraft in Germany with mixed success. The Northrop company then flew several flying wing prototypes after the war, finding these to have severe stability issues at higher angles of attack.
With the advent of Fly-By-Wire, this could be mastered, and the flying wing’s inherent low radar cross-section is used in the B-2 and B-21 US Air Force bombers.
A flying wing is not suitable for use as an air transport passenger aircraft, as passengers would feel as if they were being transported in a coffin within the wing. An evolution of the flying wing is the Blended Wing Body (BWB, Figure 1), which moves the center section forward to form a blended fuselage that houses the payload.
Figure 1. The JetZero Z4 BWB in United’s colors. Source: JetZero.
As the search for lower fuel consumption and emissions intensified, the search for a more efficient way to transport passengers has led to increased interest in the BWB concept since the early 1990s, primarily from NASA and the US aircraft industry.
The proliferation of composite primary structures since 2000 has helped address the structural problems of a BWB. This has created a renewed interest in BWBs, both for military and commercial applications.
The state of alternative propulsion aircraft? Part 7.
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By Bjorn Fehrm
March 12, 2026, © Leeham News: In our series on the state of alternative propulsion projects, we are analysing where the electric hybrid projects are and how parallel hybrids work and perform.
Figure 1. The Pratt & Whitney Parallel Hybrid DH8-100 test aircraft, presently under preparation. Source: Pratt & Whitney
We summarized the status last week and compared it to the serial hybrids that we analyzed before Christmas. Serial hybrids are motivated in special cases, but in general, they make an aircraft more expensive to produce and operate.
For those who react, “But hybrid work very well for cars”?, let’s summarize: The car thermal engines are energy hogs, and you brake away all the acceleration energy at the next stoplight. Hybrids reduce this waste by recovering energy during braking. Aircraft and aircraft engines are wonders of efficiency by comparison, and there are no energy-recovery phases in an airliner mission.
We now use our Aircraft Performance and Cost Model (APCM) to go deeper into the parallel hybrid. Can it avoid the negative verdict of the serial hybrid?
Bjorn’s Corner: Faster aircraft development. Part 30. Wrap-up.
By Bjorn Fehrm and Henry Tam
March 6, 2026, ©. Leeham News: We started the series on developing a new airliner in the 14 CFR Part 25 class (i.e., not a commuter-class aircraft) on August 1st 2025. The objective was to write a series about such development with people I knew that has “been there, done that”?
Here is how the series started:
Four years ago, I did a series on aircraft development with Henry Tam and Andrew Telesca, both part of the canceled Mitsubishi SpaceJet program. The series was about the arduous task of developing and producing a certified aircraft for the FAA Part 23 standard and its EASA equivalent. The idea was to better describe what’s ahead for the many upstarts that wanted to develop green aircraft and VTOLs. Now we will do a series about recent ideas on how the long development times for large airliners can be shortened. New projects talks about cutting the development time by one-third. Is this realistic?
The state of alternative propulsion aircraft? Part 6.
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By Bjorn Fehrm
March 5, 2026, © Leeham News: Before Christmas, we started a series examining the status of alternative propulsion projects. We finished on December 18 by looking at Series Hybrids, often as battery-electric aircraft with range extenders (Figure 1).
The range extender is the natural next step when a project realizes that a pure battery-electric aircraft won’t be able to fly the missions the market is asking for.
Figure 1. The Heart Aerospace Battery-Rlectric ES-30 with dual range extending turbo-generators in the back. Source: Heart Aerospace.
After a while, analysing the range extender, the drawbacks become increasingly obvious. Charging the battery system in flight or directly feeding the electric propulsion system from a turbogenerator is inefficient. The losses along the path from the gas turbine through a generator, an inverter, and then to a motor that drives a propeller or fan are much higher than when the gas turbine drives the propeller directly.
A series hybrid can’t compete on operational economics with the aircraft it shall replace (for example, the Cessna Caravan or the SAAB 340). Projects then turn to parallel hybrids, the subject of today’s article.
Bjorn’s Corner: Faster aircraft development. Part 29. AI and the Program Plan.
By Bjorn Fehrm and Henry Tam.
February 27, 2026, ©. Leeham News: Last week, we looked at the development timeline for Part 25 airliner programs to reach Entry Into Service (EIS) after launch, Figure 1.
We can see that development times have doubled from the 1960s to the 1980s, compared with development since the year 2000.
The main change is the complexity of the aircraft, both in terms of highly optimized structures using new materials and avionics/flight control systems with many software code lines that require extensive verification.
We concluded that modern toolchains, with the capability to produce so-called Digital Twins, helped avoid further slip in development times, but they could not reduce them. The question then remains, can the employment of AI change this?
Figure 1. The development times for airliners over the years. Source: Leeham Co.
Bjorn’s Corner: Faster aircraft development. Part 28. Development times.
By Bjorn Fehrm and Henry Tam
February 20, 2026, ©. Leeham News: We have, since August 2025, gone through an FAA CFR 14 Part 25 development project of an airliner in the 200-seat class. The aim was to identify the activities required for such a project and the regulatory actions needed to achieve Type Certification (TC) and Production Certification (OC) for the aircraft.
The program followed the time plan in Figure 1, which indicated that it would take about seven years from the start of conceptual design to deliver the first aircraft and enter service (EIS). At each phase, we assessed whether modern support techniques, such as AI, could help with development and certification and whether they would accelerate the program plan.
Figure 1. A typical Program Plan for a smooth-running Part 25 airliner development. Source: Leeham Co.
We now summarize the findings and incorporate additional modern support, such as Digital Twin support, to assess the overall impact of today’s technologies on the program plan timeline in Figure 1. Read more
Bjorn’s Corner: Faster aircraft development. Part 27. Where Speed-Up gets Tough.
By Bjorn Fehrm and Henry Tam.
February 13, 2026, ©. Leeham News: We are summarizing how modern tools, processes, and AI can help reduce the time required to develop a clean-sheet 200-seat replacement for the Airbus A321neo and the Boeing 737 MAX 10.
We discussed some ideas in the last article on how current AI can support development. We could see it helping reduce the time spent on templating documents and on designing and verifying simple parts, such as mounting brackets for pipes and cables.
To address the more challenging parts where AI struggles to assist, we need to understand why development programs now take longer than in the past and what can be done to shorten the timeline.
Outlook 2026: The state of the major eVTOL projects
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By Bjorn Fehrm
February 9, 2026, © Leeham News: The eVTOL market saw a sobering 2025 after two of its high flyers, Lilium and Volocopter, both ceased operations in 2024. The remains of Volocopter were bought by Diamond Aircraft, which now markets a stripped-down VoloCity as a Light Sports eVTOL.
Further players ceased in 2025, with Hyundai’s Supernal halting further development, as did Airbus with its CityAirbus. Textron halted Nexus development, then shuttered the division, and Overair ceased operations after Hanwa stopped investing.
We have one VTOL that received local Chinese Type Certification in 2023, and one in 2024. EHang got the Type Certificate in 2023, Production Certificate in 2024, and Air Operator Certificate (AOC) in 2025. The drone multicopter looking Ehang EH216-S (Figure 1) was cleared to operate tourist flights in China. The other Chinese project was AutoFlight’s Prosperity five-seater, which achieved Chinese Type Certification in 2024.
Figure 1. The only certified eVTOL, the EHang EH216-S. Source: EHang.
The almost euphoric enthusiasm over eVTOLs that existed before COVID, where car manufacturers got involved as this could be the thing that took over personal transport for crowded cities, has now calmed down, as the operational use of the current generation of eVTOLs is 10 to 15-minute missions in fair weather, replacing helicopter services from the airport to the city centre.
The original story was different as early developers like Joby Aviation painted with a broad brush. There were statements about 150nm trips, 200 kts speeds, and unbeatable economics, with batteries that lasted 10,000 flights. What investors and pundits didn’t understand was that these were unrelated statements about physical limits: there was no AND between them.
Bjorn’s Corner: Faster aircraft development. Part 26. AI speeds up processes.
By Bjorn Fehrm and Henry Tam
February 6, 2026, ©. Leeham News: We have completed a detailed, step-by-step analysis of the certification requirements a Part 25 Air Transport airliner in the 200-seat segment must meet.
In our series, we have seen work that could benefit from an AI agent, and other work where we conclude it will be difficult.
We begin this week by outlining areas where we expect AI to reduce the number of work hours required to complete a task. We will attribute these AI-driven work-hour reductions to the appropriate areas of the aircraft Program Plan in Figure 1.
Figure 1. A generic new Part 25 airliner development plan. Source: Leeham Co. Click to see better.
Outlook 2026: The airliner projects that promise new technology and lower emissions
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By Bjorn Fehrm
February 5, 2026, © Leeham News: We survey new entrants that deviate from the classical gas-turbine tube-and-wing airframe concept and offer airliners the promise of lower emissions and, hopefully, lower costs.
We will do this by starting with those closest to certification and delivery, then tapering off to those who currently fly on PowerPoint.
If we didn’t apply this filter to what we consider real projects, we would describe over 50 entries, with additional ones announced with airline orders every month over the last few years. Few of these have progressed beyond plans, which is why we focus on those that have.
Overall, it’s amazing that 11 years after the Airbus E-fan battery-electric aircraft flew at the Farnborough Air Show in 2014, we still do not have a single certified alternative-propulsion passenger aircraft. We have one light-sport two-seat trainer, the Pipistrel Electro Velis, but nothing else.
Figure 1. The Airbus E-Fan at the Paris Air Show in 2015. Source: Wikipedia.