Managing Editor, Leeham News & Analysis

Aeronautical and Economic Analyst, Leeham News & Analysis

Scott Hamilton

Bjorn Fehrm

In Monday’s edition of AIN’s Dubai Airshow News, <a href="https://leehamnews.com/">Leeham News and Analysis</a> gave its take on prospects for five new airliner contenders. Here, we consider the case for concepts 6-13 from this list:
<ol>
<li>Airbus A220-500</li>
<li>Boeing’s&nbsp;transonic truss-braced&nbsp;wing</li>
<li>Boom Overture supersonic transport aircraft</li>
<li>Blended wing bodies</li>
<li>Boeing's concept for a hybrid aircraft</li>
<li>Airbus ZeroE hydrogen-powered mainline jet</li>
<li>Boeing’s New Midsize Airplane</li>
<li>Boeing’s New Light Twin</li>
<li>Comac&nbsp;C929&nbsp;</li>
<li>Leeham’s&nbsp;light twin concept</li>
<li>CFM-powered Open Fan single-aisle airplane</li>
<li>Re-engined Boeing 787</li>
<li>Re-engined Airbus A350</li>
</ol>
<h2>6. Airbus’ ZeroE hydrogen airliner</h2>
The ZeroE hydrogen project was developed to be ready for production and entry into service by 2035. In February, Airbus announced it would push back the start of commercial operations for a hydrogen airliner beyond its original 2035 target.
The problem was not so much the development of the necessary system components for a hydrogen airliner, but rather the need for an airport ecosystem to produce, store, and supply hydrogen for aircraft. Progress on the equipment for airports and green hydrogen production sites was not fast enough to allow a start on commercial flights by 2035.
When Airbus announced the delay, it also stated that it had chosen the architecture for the aircraft it will produce as the ZeroE airliner. Originally, the decision was to be made in 2027 or 2028, after a hydrogen-powered GE Passport engine had been test-flown on Airbus’s A380.
Airbus had now decided that the ZeroE airliner would use a hydrogen fuel cell system to power the electric motors that drive the aircraft's propellers. It probably means the airplane will be a 100-seater, as it will be difficult to design a fuel cell system to support more than 4- to 5-megawatt engines. The Bombardier Q400, a 90-seater, has 3.5-megawatt engines.
<h2>7. Boeing’s New Midsize Airplane</h2>
The Boeing NMA was a project that spanned seven years, from 2013, when it was called the MOM (Middle of the Market airplane), until 2020, when it was canceled. Boeing was by then deep in the 737 Max crisis, and Covid hit.
The NMA had a base model with 225 seats in a U.S. domestic cabin and a stretched model with 265 seats.&nbsp;The A321 has 196 seats offering the same comfort standard. The range of the base aircraft was 5,000 nm, utilizing engines with approximately 45,000 pounds of thrust; the stretched version lost about 500 nm in range.
The reason for not launching the NMA was a gradually shrinking market; Boeing initially stated 4,000 aircraft or more, but our market analysis suggested around 2,000 aircraft. Meanwhile, Airbus, with its A321LR and announced XLR, was gradually capturing the low end of the NMA market.
Another problem was that the production cost of the NMA, using an all-composite airframe, was too high. It meant the aircraft was significantly more expensive than the A321LR/XLR, with only a 15% higher capacity in the base version. The range of the NMA was 5,000 nm, with the A321XLR offering 4,400 nm.&nbsp;The problem was that the A321LR/XLR were aluminum aircraft produced more than 10,000 times, whereas the NMA would start a production cost learning curve. It would make it significantly more expensive to produce than the A321.
The primary issue was the use of a composite structure, which was identical to that of the 787. The 787 composite technology dates back to a 2003 decision to use prepreg composite tape and autoclave-cure of the composite. Of these technologies, autoclave curing is the primary issue.
As an example, baking a wingskin in the autoclave takes half a day, and when stringers are added to the skin, we are talking about a day per two wingskins that are loaded into the autoclave. As the NMA needed four wing skins, this means that the production of these wing components would occupy an autoclave for two days. The cost of such production is too high, and the rate is too low, for the high-volume segment around the present single-aisle aircraft, where daily production rates exceed two aircraft per day.

<h2>8. Boeing’s New Light Twin</h2>
The New Light Twin can be seen as a rebirth of the NMA, albeit with a lower-cost production method. Boeing found that when marketing the NMA, airlines liked the concept of a larger aircraft in the A321XLR and 737 Max 10 market segment, which offered more seats and a slightly increased range (essentially the A321XLR range with a bit more margin for challenging routes and weather conditions).
A lower-cost, small twin-aisle aircraft with a seating capacity of 225 seats and a 5,000nm range would be attractive to the market. What the airlines didn’t like was the price tag. The capacity increase over an A321XLR was 15% for the base NMA, but the net price was over 30% higher. That didn’t work for the airlines, who told Boeing the NMA price had to come down.
The NMA’s definition in terms of size and range was attractive, and an attraction that would increase with time. The reason is that the so-called “heart of the market” for domestic and short to mid-range international flights is continually shifting upward. It used to be the size of the 737-800NG, with 170 seats, 10 years ago.&nbsp;The market has moved by around 1.5 seats per year since then.
Several factors, including Boeing's $50 billion debt, support the expectation that the A321neo and 737 Max 10 will continue production for at least another 10, if not 15, years.&nbsp;In that case, a replacement starting delivery in 2040 would be ordered with around 220 seats, and that would be for the start of the model's 40- to 50-year production run (the A320 is 37 years and the 737 is 58 years, so a planned product life of 40 to 50 years makes sense).
The $15 billion question (the development cost of a single-aisle replacement) is, should the replacement be a single aisle or a small widebody?
In this scenario, a lower-cost NMA would be an attractive option for the 2040s. The development time and initial production years, when only 10 to 20 aircraft are produced per year, easily span 10 years or more. It means the decision time for a New Light Twin would be around 2030.
It would also leave the 737 Max 10, with 196 seats, untouched, which means Boeing could continue to produce and sell the Max 10 after introducing a New Light Twin. It would complement the Max range on top of the Max 10.
How to lower the cost of the New Light Twin?&nbsp;The brunt of a cost down would come from producing the composite structure in a more modern method than the one defined for the 787 in 2003. Boeing is researching this method in the HICAM project, which aims to achieve at least a 30% cost reduction in the structure, ideally 50%.
<h2>9. Comac C929</h2>
China’s Comac is developing its first twin-aisle airplane, which is essentially a composite Airbus A330-900 or a shorter-range Boeing 787-9.&nbsp;Will this be the airplane that truly puts China’s young aerospace industry on the map? The concept was first considered in 2011 for this 290-seat aircraft.
For a time, Comac joined with Russia’s United Aircraft to proceed as a joint venture. Russia would do the composite wing. Russia’s invasion of Ukraine led to the dissolution of the joint venture, reverting it to a solo Chinese project.
There is little new technology outlined for the airplane. The C929 was planned as a full composite aircraft. Comac was responsible for the composite fuselage from the beginning. Initially, Comac contacted Boeing 787 structure suppliers, such as Italy’s Leonardo, but today it's unclear whether external suppliers will participate in building the C929 airframe.
The engines were originally to be updated versions of the GE GEnx from the 787 or Rolls-Royce Trent 7000s, used on the Airbus A330-900. However, with sanctions imposed on China for its support of Russia during the war in Ukraine, Western systems and engines intended for the C929 are now unlikely.
The Comac C919 single-aisle airplane—a competitor to the Airbus A320neo and Boeing 737 Max families—is the development ground for domestic aerospace. It, too, has recently been hampered by the sanctions. CFM Leap engine shipments were halted in the spring of 2025 but have recently resumed.
As a response, China is in the process of expanding its domestic supply chain and engine manufacturing. China’s Aero Engine Corporation of China has progressed to flight tests on a mule aircraft for an engine called CJ-1000A for the single-aisle C919.
For the larger C929, an engine project called the CJ-2000 began 10 years ago. It’s an engine in the GEnx and Trent 7000 thrust class. Its ground test version was recently showcased on Chinese television by the CEO of AECC, but the development status remains unclear.
Given the uncertainty around the supply of key technologies, the C929’s entry into service, initially scheduled for before 2030, has been pushed out. A best-guess date now is in the early 2030s.
By the time the C929 enters service, it may be little more than a “catch-up” airplane.&nbsp;The C929 could, when it finally arrives, compete with Airbus A330-900 for Chinese orders, but the A330-900 is then based on 40-year-old technology. The C929 would not be competitive with an A350-900, as it has 35 fewer seats and 2,000 nm less range.
As for Boeing’s 787, by the 2030s the basic design and technology will be 30 years old. The 787-9 will have the same seating capacity as the C929 but 1,500 nm more range. A significant refresh, as outlined below, will outclass the C929.
<h2>10. Leeham's new light twin</h2>
A Boeing New Light Twin (NLT) would be a cost-down version of the company's New Midsize Airplane (NMA) concept, entering the market as a complement to the 737 Max 10 in the late 2030s.
A new generation turbofan will only reduce the fuel consumption by about 10%. An open-fan engine can achieve a 20% improvement.
In LNA’s view, the principal reduction of CO2 and NOx emissions before 2050 comes from the replacement of the 19,000 aging aircraft of the total 27,000 that fly every day with newer, more efficient aircraft.
To achieve the maximum greenhouse gas emission reduction, the industry needs to reduce fuel consumption to the maximum. Consequently, it would make sense to equip an NLT with open-fan engines.
But the CFM RISE—the only large open-fan engine announced to date—is a 35,000-pound-thrust category engine, and we wrote that a 45,000-pound engine is needed for an NLT. Would the engine industry develop a larger open-fan engine? The question mark around such a development makes it an ambitious concept.
<h2>11. CFM-powered Open Fan single-aisle Airplane</h2>
The next generation of single-aisle airliners will focus on bringing increased efficiency while transporting more passengers. The projected size has increased by about 30 seats in the last 10 to 15 years. This means the replacement aircraft will start at around 210 to 215 seats, depending on when they enter the market, up from 200 seats right now.
The increased efficiency will mainly come from more efficient engines, though technologies such as wider wings and lighter structures will also contribute.
Regarding engines, CFM’s joint venture partners, GE Aerospace and Safran, are developing the open-fan engine called RISE (Revolutionary Innovation for Sustainable Engines). GE claims the engine’s technical challenges—noise, maintenance, cruising speed, and the risk of throwing a blade—have been solved. It also claims that the RISE will achieve 20% lower fuel burn, even after installation effects are accounted for.
So far, this is a theory, based on lab testing and ground rig testing. The engine hasn’t flown on an airplane yet and won’t until 2027, on an Airbus A380.
Pratt &amp; Whitney and Rolls-Royce are betting on a conventional turbofan. But as noted below, the expected economic improvement from a new-generation turbofan with a bypass ratio of 15 is only about 10%.
The industry political game around the engines for the next generation aircraft that will replace the A320/A321 and 737 Max is industrial poker in the super league. The outcome of all this will unfold over the coming years.
<h2>12. Re-engined Boeing 787</h2>
In 2035, the 787 will have been in service for 24 years. The engine technology will be at least 32 years old. The 787 will be due for a major engine upgrade. Will a re-engining be in the cards?
Rolls-Royce appears to have the only known development of this size engine underway. However, Pratt &amp; Whitney has always said its Geared Turbofan engine can be upscaled to as much as 100,000 pounds of thrust, and GE can use technologies from the Boeing 777-9 GE9X to develop a new generation of GEnx engines.
The improvement in fuel efficiency from these engines will be 10% or less. The reason is that the installation on existing airframes limits the possible engine bypass ratios to 15 or less. When the last generational engine update&nbsp;delivered a 15% improvement, it was because bypass ratios&nbsp;could be doubled—from four to five for the CFM56 and IAE V2500,&nbsp;to 10 or higher for the CFM Leap and Pratt &amp; Whitney GTF.
But the bypass ratio increase now stays at 50% (from ~10 to ~15), effectively halving the fuel efficiency gain from propulsive efficiency. The second improvement area is core efficiency, but it involves higher pressure ratios and temperatures. Given the reliability issues with the GEnx, Trent 1000, Leap, and GTF engines, airlines will likely be reluctant to accept a “hot core” next-generation engine.

<h2>13. Re-engined Airbus A350</h2>
The slightly younger A350 faces similar aging engine technology, and a similar need to upgrade the engine appears in the next decade. Rolls-Royce has an exclusive engine supplier position on the A350. If a re-engine or continual improvements and upgrades are the choice, Rolls-Royce will be the likely supplier.
The Trent XWB 84 on the A350-900 had superior entry-into-service reliability and durability. The larger Trent XWB 97 on the larger A350-1000, on the other hand, had durability issues in the harsh Middle East and super-salty environments, giving Qatar Airways, Etihad Airways, and Cathay Pacific Airways far shorter on-wing time than expected.
Rolls-Royce has made great progress in resolving these issues. Further evolution of the Trent XWB engine or the new Ultra Fan will benefit from this experience. As explained above, we can expect an upgraded A350 to achieve about a 10% improvement in fuel consumption.
The timing of an upgrade will be influenced by fuel prices and airlines' appetite for new, more efficient engines that avoid the durability dramas of recent engine introductions.
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