Leeham News and Analysis
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Bjorn’s Corner: Blended Wing Body Airliners. Part 7
By Bjorn Fehrm
April 24, 2026, ©. Leeham News: We are making a series of articles on the Blended Wing Body (BWB) as a potentially more efficient design for passenger-carrying airliners than the classical Tube-And-Wing (TAW) configuration.
In the sixth article last week, we discussed how the drag characteristics of the BWB and a high optimal cruise altitude have consequences for the choice of engines. The thrust lapse due to altitude is higher than for Tube-And-Wing aircraft that fly about 10,000ft lower. The JetZero Z4, therefore, needs engines adapted for high climbs and cruise conditions.
This requires engines with higher specific thrust, which means lower Bypass Ratios (BPRs). This runs counter to the development trend of modern engines, which reduce specific thrust in each generation to improve propulsive efficiency and thus lower fuel burn.
Figure 1. The JetZero Z4 BWB. Source: JetZero.
Now we look at the challenges in the structure domain for a BWB. At first glance, it should be a lighter structure than a Tube-And-Wing aircraft, as it does away with the fuselage and empennage. In reality, it’s more complicated than that.
Bjorn’s Corner: Blended Wing Body Airliners. Part 6
By Bjorn Fehrm
April 17, 2026, ©. Leeham News: We have started a series of articles on the Blended Wing Body (BWB) as a potentially more efficient design for passenger-carrying airliners than the classical Tube-And-Wing (TAW) configuration.
In the fifth article last week, we discussed how the drag characteristics of the BWB are different from a classical Tube-And-Wing airliner. The dominance of air-friction drag over induced drag results in a 10,000ft higher optimal cruise altitude compared with an equal-capacity TAW.
We compared JetZero’s Z4 project to a 250-seat variant of Boeing’s NMA that we have analyzed several times with our Aircraft Performance and Cost Model, APCM. Both aircraft use modern composite structures, aerodynamics, and systems, resulting in similar overall weights and drag.
Figure 1. The JetZero Z4 BWB. Source: JetZero.
The difference is how the drag is partitioned between the wetted area caused drag (air friction drag) and drag due to weight (induced drag). The difference between drag and optimal cruise altitudes has consequences for engine choice. Here is how.
Bjorn’s Corner: Blended Wing Body Airliners. Part 5
By Bjorn Fehrm
April 10, 2026, ©. Leeham News: We have started a series of articles on the Blended Wing Body (BWB) as a potentially more efficient design for passenger-carrying airliners than the classical Tube-And-Wing (TAW) configuration.
In last week’s article, we discussed how the wingspan is an important factor in an airliner’s takeoff performance. The induced drag is about 85-90% of the drag at the critical V2 point after rotation, where regulations require that a twin-engined airliner be able to fly on one engine with a climb rate of 2.4%.
We now go through the entire mission for a BWB airliner and compare its drag characteristics with those of a classical Tube-And-Wing (TAW) design.
Figure 1. The JetZero Z4 BWB. Source: JetZero.
Bjorn’s Corner: Blended Wing Body Airliners. Part 3.
By Bjorn Fehrm
March 27, 2026, ©. Leeham News: We have started a series of articles about the Blended WingBody (BWB) as a potentially more efficient passenger-carrying airliner design than the classical Tube And Wing (TAW) configuration.
In the second article last week, we saw that the aircraft skin surface area, which creates the dominant skin friction drag, was smaller than that of the same capacity Boeing 767 for the 250-seat JetZero Z4, but not for the 165-seat Ascent1000, compared with the Boeing 737 MAX 8.
Both the Z4 and the Ascent1000 had a larger wingspan than the 767 and 737-8, but this is comparing future concepts with older aircraft. The Ascent1000 has folding wingtips to fit in the 36m gate, which a TAW replacement for the MAX 8 would also have. The Z4 and the 767 must use widebody gates.
Figure 1. The JetZero Z4 BWB. Source: JetZero.
Why do the BWBs have such large wetted areas when they lack a fuselage and empennage? It’s because they lack a tailplane! Why does a lack of a tailplane force a larger BWB wing?
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.
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.
Bjorn’s Corner: Faster aircraft development. Part 1.
By Bjorn Fehrm
August 1, 2025, ©. Leeham News: Four years ago I did a series about aircraft development together with Henry Tam and Andrew Telesca. Both worked on the Mitsubishi Spacejet program. You can find the series here.
It 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 9-seat and 19-seat alternative propulsion aircraft.
Now we do a series about recent ideas on how the long development times for large airliners can be shortened. New projects talk about cutting development calendar time by one-third or more. Is this realistic?
Figure 1. The A350 development schedule from December 2011. Source: Airbus.
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What’s the next new aircraft? Part 3
By Scott Hamilton and Bjorn Fehrm
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July 24, 2025, © Leeham News: In Part 3 of our five-part series on examining the potential next generation of aircraft in the coming decades, we take a closer look at Aircraft projects 1 to 4 in our Figure 1.
Figure 1. The 13 airliner ideas we look at in the series. Source: Leeham Co.
These are the (1) A220-500, (2) Boeing’s Transonic Truss Brace Wing (TTBW), (3) Boom’s Overture Super Sonic Transport (SST), and (4) the Blended Wing Body (BWB) aircraft suggested by leading proponent Jet Zero.
What’s the next new aircraft, Part 2
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By Bjorn Fehrm
July 21, 2025, © Leeham News: Our series about “What’s the next new aircraft” was introduced last week, where we look at what potential new aircraft could be introduced over the following decades, and what technologies these would use.
In Part 2 of the five-part series, we introduce some basics around aircraft efficiency and examine what areas these 13 new aircraft aim to improve to enhance their efficiency.
In the following Parts, we will look into these aircraft in more detail and write about how challenging it will be to develop and mature the needed technologies.
Figure 1. The 13 new aircraft concepts that we study. Source: Leeham Co.