Engine Development. Part 5. The Turbofans go High Bypass

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By Bjorn Fehrm


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.

  • 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.

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Engine Development. Part 4. Turbofans go mainstream.

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By Bjorn Fehrm


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.


  • 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.

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Commercial Aircraft programs duration from launch to delivery over the years

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By Vincent Valery


June 20, 2022, © Leeham News: New airplane programs used to come to market in four years. Now, the launch-to-entry-into-service period has been seven years or more. (Chinese and Russian programs take even longer.)

Boeing launched the 787 in December 2003. EIS was October 2011. Airbus’ A350, launched in response to the 787 in 2004, went through several iterations which added time to the program. Delays added more time. EIS was in January 2015.

Bombardier’s C Series was launched in 2008. EIS was in July 2016. The Boeing 777X was launched in 2013. EIS is now targeted for 2025. Boeing launched the 747-8 in 2005. EIS was in 2011. The Boeing 737 MAX was launched in July 2011. EIS was May 2017. Airbus’ A320neo was launched in December 2010. EIS was in January 2016.

Boeing has been discussing the New Midmarket Airplane (or whatever it was called throughout changing nomenclature) since 2012. It still hasn’t launched the program. Once it does, how long will it take to enter service?

Credit: Boeing

Any new program is a multi-year, multi-million investment that, in the worst case, can take decades before recovering the initial development and production ramp-up expenditures.

Several recent programs, notably the 777X, have faced significant delays between the envisioned and actual start of deliveries to airlines.

Boeing claims that advances in manufacturing techniques will reduce the time required to develop the next aircraft program. However, regulatory scrutiny is higher nowadays and the aircraft built are more complex than in previous generations.

LNA analyzes how the time between the program launch and entry into service has evolved since the beginning of the Jet Age. The goal is to find whether there is a trend and in what direction. The analysis focuses on Airbus, Boeing, Lockheed, and McDonnell Douglas.

  • An unmistakable trend;
  • The latest clean sheet designs took significantly longer;
  • Engine development dictates recent derivative program timelines;
  • Future program considerations.

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A history of jet freighter aircraft

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By Vincent Valery


A Cathay Pacific 747-8F

July 29, 2021, © Leeham News: Last week, LNA compared the performance of the 777F against the A350F, launched today. As a follow-up, we thought it relevant to look at the history of freighter aircraft derived from passenger jets at the major OEMs.

Shortly after the dawn of the jet age, Boeing and McDonnell Douglas started selling freighter variants of their 707 and DC-8, respectively. Most aircraft families developed later at both OEMs would receive a freighter variant in one form or another.

We will stick for our analysis to Freighter aircraft delivered off the assembly line at the world’s Western OEMs: Airbus, Boeing, Lockheed, and McDonnell Douglas.

  • What is a Freighter aircraft?
  • A minor but worthwhile market after initial euphoria;
  • Single-aisle against twin-aisle;
  • A Queen of the Freighters;
  • An OEM’s fortress is another’s weakness.

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Industry stands together on safety

By Scott Correa

Special to Leeham News

 May 27, 2021, © Leeham News: Forty-two years ago this week, I puked at work.

American Airlines flight 191 moments before crashing less than a mile after takeoff at Chicago O’Hare Airport. Source: Wikipedia.

On May 25, 1979, an American Airlines McDonnell Douglas DC-10 crashed on take off from Chicago’s O’Hare International Airport. Within minutes, it was known that the No. 1 engine separated from the airplane just after the airplane was committed.

The aircraft gained a few hundred feet before rolling over on its left wing, crashing into a trailer park. All 271 on board and two people on the ground were killed.

The Federal Aviation Administration immediately grounded all DC-10s in the US because of the engine separation. Regulators elsewhere in the world followed suit.

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Pontifications: A330-300 could be great deal ahead

May 10, 2021, © Leeham News: The COVID-19 pandemic prompted airlines to ground more than 8,000 aircraft at the peak.

By Scott Hamilton

Among widebodies, no aircraft was hit harder than the Airbus A330ceo.

Traffic within China, the US and Asia recovers with narrowbody airplanes. European short- and medium-haul traffic is not recovering as quickly due to continued boarder closings. International traffic, for the same reason, remains awful.

But in chaos some see opportunities.

Jep Thornton, managing partner of the boutique lessor Aerolease, last week said the A330-300 could be a great trading opportunity.

At April 1, there were 267 -300s and 286 A330-200s (of all types) in storage, according to data reviewed by LNA.

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Boeing should build 757 replacement in Washington


Dec. 22, 2020, © Leeham News: If you get a chance over the next few weeks – in between binge-watching The Queen’s Gambit, putting up the 79 extra feet of Christmas lights you ordered this year and figuring out how to buy surprise Christmas gifts for your spouse when you have a joint Amazon account – you should take 90 minutes to watch this video from our friends at the International Association of Machinists District Lodge 751.

By Bryan Corliss

The Machinists on Dec. 8 hosted (on Zoom, of course) a high-level panel discussion about the state of the aerospace industry and Washington state’s role in it, featuring a whole bunch of Brand-Name People Who are Smarter Than Me(c).

They shared their insights for those of us coffee-drinkers who are trying to read the tea leaves to divine what Boeing’s next moves should be as it tries to get back on its feet – and what the implications are for its home state.

The takeaway:

The problems for Boeing are obvious, and the solutions are pretty clear – but doing the smart thing would require a major cultural shift from an executive team that’s locked into a 1990s vision of how business gets done.

  • Boeing needs a 757 replacement this decade
  • It should get built in Washington state
  • There are concrete – and audacious – steps for the state to take
  • Can GE alum Calhoun change Boeing’s GE culture?

    Buzz about Boeing’s next new airplane returned this month to making a 757 replacement. Boeing photo.

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Pontifications: Recertification flights for Boeing 737 MAX appear close

By Scott Hamilton

June 29, 2020, © Leeham News: Boeing may be set to begin recertification flights of the 737 MAX as early as today, The Seattle Times reported last week.

Testing will take three days, if all goes well. But Boeing still has a lot of work to do to fully satisfy regulators.

According to The Times, Transport Canada and Europe’s EASA require additional modifications to enhance safety on the MAX. The additional changes may not be required for certification but must be done within a year, the paper reports. The MAX 10 must have the changes before it is certified.

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An accelerating widebody fleet streamlining, Part 1

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By Vincent Valery


June 1, 2020, © Leeham News: As airlines slashed capacity in the aftermath of the COVID-19 outbreak, some took the opportunity to accelerate aircraft retirements.

Older generation twin-aisle aircraft, notably the Airbus A340, older A330s, Boeing 747 and 767, have exited numerous carrier’s fleet early. Several Airbus A380 operators put their Superjumbos in long-term storage, wondering whether these will ever fly in passenger service again.

Major crises tend to accelerate existing trends. The move away from large twin-aisle aircraft is a case in point. In the context of subdued demand for several years, airlines will be under pressure to reduce expenses. Streamlining fleets is an obvious target.

The Airbus A320 and Boeing 737 families dominated the single-aisle market for decades. The picture has historically been far more fragmented for twin-aisle aircraft. Airbus and Boeing still have three widebody aircraft families apiece with significant numbers of passenger aircraft in service.

LNA analyzes in two-part articles why the picture will likely change for the widebody market in the 2020s. In the first part, we will take a historical detour to analyze why twin-aisle fleets are still so fragmented nowadays.

  • Range going hand in hand with aircraft size;
  • Change in the 1990s;
  • Superjumbo gamble backfires;
  • Full widebody fleet streamlining becomes a reality.

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Pontifications: The nuts and bolts of air disasters

March 9, 2020, © Leeham News: Commercial aviation accidents are high profile news events.

By Scott Hamilton

These happen rarely. Many times, a lot of people are killed. (It should be noted that often survivors may outnumber those killed as safety improved.)

In this era of 24/7 cable news and minute-by minute social media, everyone wants instant answers as to causes.

Finding answers is not simple. A typical accident investigation usually takes 12-18 months before the investigators issue a final report with a probable cause.

One reason for this is that sometimes, the cause of an accident comes down to a single bolt, or even a single cotter pin.

This is where the new book, Flight Failure, Investigating the Nuts and Bolts of Air Disasters and Aviation Safety, serves to remind us of just how intricate accident investigation is.

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