Bjorn’s Corner: New engine development. Part 10. Propeller, Rotor or Fan?

By Bjorn Fehrm

June 7, 2024, ©. Leeham News: We do an article series about engine development. The aim is to understand why engine development now has longer timelines than airframe development and carries larger risks of product maturity problems.

To understand why engine development has become a challenging task, we need to understand engine fundamentals and the technologies used for these fundamentals.

Following the last Corner on airframe integration, several comments were made about the definition of propeller, open rotor, and/or fan. So, we’ll explore this further.

Figure 1. Evolution of Wright Brothers propellers from 1903 to 1905. Source: wright-brothers.org

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Bjorn’s Corner: New engine development. Part 10. Airframe integration

By Bjorn Fehrm

May 24, 2024, ©. Leeham News: We do an article series about engine development. The aim is to understand why engine development now has longer timelines than airframe development and carries larger risks of product maturity problems.

To understand why engine development has become a challenging task, we need to understand engine fundamentals and the technologies used for these fundamentals.

In the last Corner, we looked at the nacelles used for a turbofan engine and for an open-rotor engine. Now, we go one step further and look at the integration of modern engines on an airliner.

Figure 1. Boeing 737NG (left) and MAX (right) nacelles compared. Source: Leeham Graphic from Boeing 737 images.

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Bjorn’s Corner: New engine development. Part 5. Turbofan design problems

By Bjorn Fehrm

April 26, 2024, ©. Leeham News: We do an article series about engine development. The aim is to understand why engine development now dominates new airliner development when it comes to the needed calendar time and risks.

To understand why engine development has become a challenging task, we need to understand engine fundamentals and the technologies used for these fundamentals.

We discussed geared versus direct-drive turbofans last week. Now, we’ll examine some design problems for these engines.

Figure 1. The Pratt & Whitney PW1100G geared turbofan, with its unique aluminum fan. Source: Pratt & Whitney.

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Bjorn’ s Corner: Engine development. Part 1. Introduction

March 29, 2024, ©. Leeham News: We finished our article series about New Aircraft Technologies last week. It dealt with the different new technologies that a next-generation airliner could use to increase efficiency and by it environmental emissions.

An area that we touched upon but didn’t dig deeper into was engine development. When airframe development historically decided how long a new generation of aircraft took to develop, it gradually changed to engine development being the more calendar-time-consuming and riskier development for the last generations. This article series will discuss why and what can be done about it.

Figure 1. CFM RISE, a new engine development for the next generation of airliners. Source: CFM.

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Re-engining the Boeing 767, Part 2

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By Bjorn Fehrm

December 14, 2023, © Leeham News: We are looking at a re-engine of the 767, a move that Boeing is considering to avoid a production stop after 2027. The present 767 engines don’t pass emission regulations introduced by FAA, EASA, and other regulators for production and delivery beyond 2027.

We have described the history of the 767 and the key data of the different variants in last week’s article. Now, we look at what airframe modifications are necessary to house more efficient engines and what consequences these bring.

Summary:
  • New, more environmentally friendly engines for the 767 mean changes to the landing gear and structures to house larger and heavier engines.
  • For the payload capacity to stay the same a deeper grab in the 767-400 toolbox is necessary than just adopting the landing gear.

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Pontifications: Airbus ponders A330neo MRTT, Boeing ponders KC-46A re-engine

By Scott Hamilton

By Scott Hamilton

Nov. 28, 2023, © Leeham News: In a reversal of intent, the airplane that Airbus may submit to the US Air Force for the next round of aerial tanker procurement may be based on the A330neo instead of the current production A330-200ceo MRTT.

The Air Force, however, may forego competition between Airbus and Boeing and place a sole-source follow-on order with Boeing for the KC-46A tanker, based on the 767-200ER. Boeing already has a contract for 179 KC-46As, and the USAF appears to be leaning toward a sole-source award. Political pressure from Airbus partisans and others who favor competition may prevail.


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Airbus wants to discontinue production of the A330-200ceo-based MRTT. The neo-based version would be based on the A330-800. Sales of the -800 are poor—fewer than 20 have been ordered. An -800 based MRTT will breathe life into the nearly still-born model.


  • Boeing considers re-engining the 767-300ERF and the KC-46A.
  • KC-46A, 767-200, A330 MRTT exempt from 2027 ICAO standards.

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Pontifications: “We’re sick and tired of new technologies:” Avolon CEO

By Scott Hamilton

Editor’s Note: As Airbus and Boeing consider new airplanes, their current generation aircraft are plagued with technical issues. The engines on the A320neo and 737 MAX families continue to have problems years after entry into service. The Boeing 787, which had ground-breaking technology when it was designed, has production issues. Flight testing early on revealed technical problems with the engine on the 777X, prompting the president of Emirates Airline to publicly suggest he won’t accept delivery until the engines are fully “mature.”

Aviation Week’s Check 6 podcast last week examined Boeing’s path toward a new airplane. Boeing CEO David Calhoun insists on waiting for new technology. But “new technology,” while in theory is a great idea, the phrase also scares people. LNA reported on this in March 2020. We’re reposting this article from then.


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Introduction

By Scott Hamilton

March 16, 2020, © Leeham News: “I can tell you from our perspective, we’re kind of sick and tired of new, new technology. It’s not proven to be the home run.”

This blunt assessment comes from the chief executive officer of the big aircraft lessor, Avolon.

Domhnal Slattery

Domhnal Slattery, the CEO, was giving his critique of whether Boeing should launch a new airplane once the 737 MAX crisis is over. (Update: Since this interview, Slattery retired from Avolon.)

Boeing was on a path to decide whether to launch the New Midmarket Airplane when the MAX was grounded one year ago this month.

Airbus was waiting for Boeing to move before deciding how to respond.

Summary
  • Airbus and Boeing should “stick to their knitting.”
  • Focus on incremental improvements for now.
  • 2030s to 2050s will be the next big advance in technologies.

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Pontifications: Moonshot for engines for Next Boeing Airplane may have to wait

By Scott Hamilton

Sept. 12, 2023, © Leeham News: The Next Boeing Airplane (NBA) may be a moonshot for CEO David Calhoun, but airlines will probably be reluctant to take a moonshot on the next new engine.

Service issues with the CFM LEAP and Pratt & Whitney GTF engines are driving airlines batty. The failures of the Rolls-Royce Trent 1000 years after entry-into-service (EIS) cost RR hundreds and millions of dollars and a confidence crisis that hurt future sales. LEAP engines are coming off wing well before initial forecasts. Every aircraft model using the GTF faced groundings as engine failures piled up.

Boeing sorely needs a successor to the 737, now in its 55th year and fourth iteration. Ron Epstein, the aerospace analyst for Bank of America, was biting in a Sept. 7 research note.

Flying a Boeing 737 is like driving a ‘68 Chevy Impala with a semi-modern dash.

 “We note that Boeing continues to ride on the coattails of its past glory. The original Boeing 737 prototype first flew in April 1967, entering service less than a year later in February 1968 with Lufthansa. Fifty-five years later, the 737 airframe remains in service through a multitude of derivative models, including the most recent 737 MAX,” he wrote.

“However, we note that the model was never intended to be such a blockbuster long-term solution. Instead, the 737 was expected to be a band-aid for the Boeing portfolio to compete with the market share-winning DC-9. The Boeing fleet lacked a smaller narrowbody model to complement the company’s larger jets, like the 707. In the spirit of the General Motors model, the 737 was intended to be the ‘cheap Chevy’ of the portfolio. Fledgling carriers would operate the cheaper model before upgrading to Boeing’s large, higher-end products like the 707 and, later, the 747, which one could see as the ‘Cadillacs’ of the portfolio.

“In our view, while the longevity of the 737 is impressive, the aircraft is now a bit of an anachronism. Operating the aircraft is like driving around in a 1968 Chevy Impala with a semi-modern dashboard. It is important to note that the 737 is the only currently manufactured commercial aircraft without fly-by-wire controls, which are a staple in modern aircraft control system design.”

Epstein worked for Boeing from 1995 to 1999 as an Applied Research Scientist. He’s a technical advisor to United Airlines for the alternative energy sector.

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Airbus 1H2023 results: Supply chain limits Airbus’ growth

July 26, 2023, © Leeham News: Airbus has presented its results for the first half year of 2023. A few critical suppliers are still Airbus’ constraint for growth.

The orders are there, and the Final Assembly Lines as well. But the supply chain is maxed out, gradually taking Airbus to 75 A321/A320 a month by 2026.

For 2023 things are on track. The company sticks to its 2023 guidance of delivering 720 commercial aircraft with an EBIT adjusted of €6bn and Free cash flow of €3bn.

For 2024 and 2025, Airbus CEO Guillame Faury cautioned that the RTX GTF engine turbine disc inspections could strain an already challenged GTF MRO capacity further.

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Day One at Paris: Airbus lands record IndiGo deal for 500 A320s

By Bryan Corliss

Monday, June 19, 2023, © Leeham News – Airbus landed a huge but widely expected order for 500 A320s from Indian carrier IndiGo, as the 2023 Paris Air Show got underway Monday.

Analysts had issued pre-show forecasts that orders for as many as 3,000 jets will be announced this week at Le Bourget, as airlines place big bets on a continuing industry recovery from the Covid-19 pandemic worldwide.

Despite the lofty projections, the show got off to a slow start, with only a handful of minor announcements until IndiGo’s big splash late in the Paris afternoon.

  • IndiGo has nearly 1,000 Airbus jets on order
  • Airbus snags A350 order; could add more
  • Boeing announces pilot training deal
  • De Havilland Canada plans upgraded Twin Otter

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