Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Spirit Aero teeters on bankruptcy, but what’s new about that? February 10, 2025
- Trump vows to add tariffs to aluminum and steel; Airbus, Boeing, suppliers will be impacted February 10, 2025
- JetZero sees big sales potential, but consultants say it won’t be them to bring BWB to market February 10, 2025
- Bjorn’s Corner: Air Transport’s route to 2050. Part 8 February 7, 2025
- Hopes, skepticism, for Boeing from suppliers February 6, 2025
Engine Development. Part 7. Engine reliability changes the aircraft market
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By Bjorn Fehrm
Introduction
September 29, 2022, © Leeham News: The 1970s saw the introduction of the High Bypass engine for the medium/long range Boeing 747, Douglas DC-10, and Lockheed Tristar, with Airbus A300 employing an updated variant of the DC-10 engine for medium range missions.
In the following decades, these engines introduced improved technology and matured into new levels of reliability. With the increase in reliability came changes in how long-range aircraft were designed.
Figure 1. The Boeing 777-200 was introduced by United Airlines in 1995. Source: Wikipedia.
Summary
- The engine development after the introduction of the high bypass turbofans in the 1970s focused on reliability and higher efficiency rather than new design principles.
- The change in reliability made the two-engined long-range aircraft the winner over three and four-engine aircraft.
Engine Development. Part 6. High Bypass goes mainstream
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By Bjorn Fehrm
Introduction
September 22, 2022, © Leeham News: With the introduction of the High Bypass engine for the Boeing 747, Douglas DC-10, and Lockheed Tristar, it was obvious Pratt & Whitney’s low bypass engines on the Boeing 707, 727, 737, and Douglas DC-8, -9 should be attacked with a new High Bypass engine in this thrust class.
French Snecma and GE teamed up to break Pratt & Whitney’s monopoly of the jet engine market outside the widebodies. The CFM56 was born.
Figure 1. The Boeing 737-300, the breakthrough for the CFM56 engine. Source; Wikipedia.
Summary
- With an exclusive fit on the Boeing 737 and a 10-year introduction advantage on the A320, the CFM56 has dominated over the competing IAE V2500.
- The CFM56 is the world’s most produced jet engine, with over 32,000 engines produced to date.
Pontifications: No engines, billions shy, devastating enviro analysis, Boom’s CEO still exudes optimism
By Scott Hamilton
Sept. 20, 2022, © Leeham News: Blake Scholl, the founder and CEO of Boom, the start-up company, continued to paint an optimistic picture about the Overture Supersonic Transport.
He told the US Chamber of Commerce Aerospace Summit last week that the Overture, a Mach 1.7 88-passenger aircraft concept, will revolutionize international air travel.
But Boom has big challenges ahead—not the least of which is that there is no engine manufacturer so far that has stepped up to provide an engine. The Big Three—GE Aviation, Pratt & Whitney, and Rolls-Royce—have either outright rejected participation or other priorities exist.
Plethora of Challenges
- Rolls says publicly it won’t pursue an engine for Boom. GE told LNA it’s not interested in developing an engine for Boom. P&W is focused on advances for its GTF, developing sustainable technology and military engines.
- The International Civil Aviation Organization (ICAO) in July issued a report on the environment that eviscerated SSTs and the SAF concept outlined for Boom. The report included analysis from the International Council on Clean Transportation (ICCT).
- Scholl claims a market demand for thousands of SSTs but Boom’s 2013 study by Boyd International forecast a market demand over the life of the program of 1,318 Overtures. Some thought this figure was generous.
- Boyd’s report also concludes Boom needs a Mach 2.2 airplane to be commercially viable. Scholl reduced the speed to 1.7. This means that in some cases, airline crews can’t do a round trip from the US to Europe without a relief crew, which upsets some of the economics.
- If Boom were a publicly traded company, all the orders would fall under the ASC 606 accounting rule that questions the viability of those orders.
- Scholl told AIN Online Boom needs $6bn to $8bn to come to market and so far, it has raised $600m.
- And we don’t get into the certification and regulatory hurdles. Among them: In his presentation to the Chamber, Scholl said there are 600 potential SST markets. He included some inland in the US, where there is a ban on SSTs flying over land.
Engine Development. Part 5. The Turbofans go High Bypass
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By Bjorn Fehrm
Introduction
September 15, 2022, © Leeham News: Last week, we looked at how Pratt & Whitney’s JT8D turbofan came to dominate short-haul airliners while the JT3D had the long-range market.
The introduction of the widebody jets in the 1970s with Boeing 747, Douglas DC-10, and Lockheed Tristar brought GE and Rolls-Royce into the market. It was the start of the high bypass turbofans.
Figure 1. The roll-out of the Boeing 747-100 on September 30, 1968.
Summary
- The military TF39 for Lockheed C-5 Galaxy military transport set the benchmark for the new generation of high bypass turbofans with its 8-to-1 bypass ratio.
- Pratt & Whitney, GE, and Rolls-Royce developed civil engines along the lines of the TF39 for the new generation widebodies.
Engine Development. Part 4. Turbofans go mainstream.
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By Bjorn Fehrm
Introduction
September 8, 2022, © Leeham News: Last week, we analyzed the change from turbojets to turbofans for civil air transport. The jet engine was developed for high-speed military fighters and was not ideal for subsonic airliner use.
We also dwelled on why the three major engine OEMs came to different solutions for the first-generation turbofans. Now we look at the engine that made turbofans mainstream, the Pratt & Whitney JT8.
Figure 1. The Boeing 727-100 with Pratt & Whitney JT8 engines. Source: Wikipedia.
Summary
- The JT8 competed with the more developed Rolls-Royce Spey to engine the first US domestic jet airliner, the Boeing 727.
- After it captured the Boeing 727, it went on to engine all US short and median haul jets of the 1960s.
Engine Development. Part 3. The early turbofans.
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By Bjorn Fehrm
Introduction
September 1, 2022, © Leeham News: Last week, we looked at the motivation to change from propeller engines to jet engines as higher cruising speeds were sought for airliners.
We learned the straight jet engine, while good for military jets, wasn’t well suited for civil airliners. It was noisy and fuel-thirsty. It was why the subsequent engine development, the turbofan, was quickly accepted by the airlines.
Figure 1. A Boeing 707 with Pratt & Whitney JT3D turbofan engines. Source: Wikipedia.
Summary
- The first turbofans from Rolls-Royce, Pratt & Whitney, and GE had different designs.
- The advantages of the turbofan over the straight jet were quickly recognized. The turbofan has been the choice for airliners since the late 1950s.
Engine Development. Part 2. The early jet engines.
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By Bjorn Fehrm
Introduction
August 25, 2022, © Leeham News: Last week, we started a series about jet engine development for our air transport aircraft. The jet engine came to replace the piston and gas turbine propeller engines when airplanes sought higher cruising speeds.
In the second part of the series, we look at why the jet engines were developed and their advantages and disadvantages compared to what they replaced.
De Havilland Comet, the first jet airliner. Source; Wikipedia.
Summary
- When the propeller engine came to its speed limits, the straight jet engine was the answer.
- While it helped with speed, it created other problems.
Bjorn’s Corner: Sustainable Air Transport. Part 33. eVTOL batteries.
August 19, 2022, ©. Leeham News: This is a summary of article Part 33P, eVTOL batteries. This article discusses the trickiest system on an eVTOL, the battery system.
The battery system supplies the energy to the VTOL, and given today’s and tomorrow’s battery technology; it’s a tight resource that needs a lot of pampering.
Figure 1. We use graphs in the Pipistrel spare parts catalog to show the battery system of the Pipistrel Velis Electro. Source: Pipistrel and Leeham Co.
Engine Development, Part 1: Launch to Entry into Service
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By Vincent Valery
Introduction
Pratt & Whitney Geared Turbofan
Aug 18, 2022, © Leeham News: LNA analyzed the evolution of commercial aircraft development timelines last month. The time between a program launch and entry into service significantly increased over time, including for derivatives.
The increase in development time is primarily the result of more complex and safer airplanes. Introducing new materials, notably a more extensive use of composites, also explain longer development timelines.
LNA now starts a new series on the topic of commercial aircraft jet engines. The goal is to go through significant innovations from the beginning of the jet age.
This first article analyses whether engine development time between launch and entry into service increased significantly over time.
Summary
- Military development led to the first commercial jet engines;
- The divergence between military and commercial programs;
- Pushing the envelope of the same fundamental engine architecture;
- Harder to identify development timeline evolution.
Pontifications: Rolls-Royce and the Next Boeing Airplane
April 18, 2022, © Leeham News: The aviation industry is waiting to see what Boeing will do when it comes to a new airplane.
By Scott Hamilton
The Next Boeing Airplane (NBA), whatever form it takes, will largely be driven by what advances in engines are available. Boeing CEO David Calhoun downplays the engine element. He’s said repeatedly that the next engine will only have about a 10% lower fuel consumption than today’s powerplants. He didn’t today’s name engines, but the benchmarks are now the Pratt & Whitney Geared Turbo Fan and CFM LEAP.
Calhoun places more emphasis on a moonshot in design and production advances to lower the cost of the airplane—with the theory the price paid by the customer will be lower as a result, providing a combined benefit of lower operating costs and lower capital costs.
PW agrees that by around 2030, the usual date (plus-or-minus a year or two) given for the NBA’s entry into service (EIS), it can get another 10% of improved fuel economy out of the GTF. CFM, on the other hand, is pressing ahead with what used to be called the Open Rotor concept. CFM now calls it an Open Fan. The company has a target EIS of 2035 and a fuel improvement of 20%. Emissions for the two engines would be reduced by roughly a corresponding amount vis-à-vis fuel burn.
