Leeham News and Analysis
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Leeham News and Analysis
- Bjorn’s Corner: Air Transport’s route to 2050. Part 21. May 9, 2025
- Does an A220-500 need a new wing and engines? Part 2. May 8, 2025
- Embraer downplays tariff impact on 2025 results May 6, 2025
- JetZero readies effort for private equity fund raising May 5, 2025
- Bjorn’s Corner: Air Transport’s route to 2050. Part 20. May 2, 2025
The Boom SST engine problem, Part 3
By Bjorn Fehrm
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Introduction
December 08, 2016, ©. Leeham Co: Boom Technology and Virgin Atlantic plan to offer supersonic business class passenger traffic over the Atlantic. We covered the type of challenges that this poses in previous articles. The most difficult challenge is finding a suitable engine.
Figure 1. Boom Technologies Boom Mach 2.2 airliner with 45 seater. Source: Boom.
We described what type of engine will be required in Part 2 of the series. We will now investigate what thrust this engine must deliver at different parts of the flight envelope.
How “draggy” is supersonic flight? Why did Concorde and the Tu-144 need afterburners for the acceleration to cruise speed?
Summary:
- Supersonic drag forces slender aircraft designs to minimize supersonic drag.
- An SST needs to use a special climb technique to hold this and other drag factors low.
- Passing the sound barrier and supersonic climb is demanding flight phases
- Can a non-afterburning turbofan operate efficiently to master these phases and combat the supersonic drag?
Pontifications: Making sense of WTO Boeing subsidy case
By Scott Hamilton
Dec. 5, 2016, © Leeham Co.: Far be it from me to say, I told you so.
But I did.
When Washington State extended the Boeing 787 tax breaks in November 2013 to the 777X through 2040, I wrote and told everyone who would listen (and even those who wouldn’t) that the 787 tax breaks had been found illegal. So extending them was extending illegal tax breaks.
Bjorn’s Corner: Turbofan engine challenges, Part 5
By Bjorn Fehrm
December 02, 2016, ©. Leeham Co: We will now look at the combustor area in our series on modern turbofan engines. There is a lot of activity in this area, as it sets the level of pollution for the air transportation industry for some important combustion products.
We will also finish off the compressor part of our series by looking at the bleeding of cooling air for the engine and for servicing the aircraft with air conditioning and deicing air.
Figure 1. GasTurb principal representation of a three-shaft turbofan like our reference Rolls-Royce Trent XWB. Source: GasTurb.
The amount of air which is tapped from compressor stages for cooling and other purposes can exceed 20% of the core flow (some of the flow paths are shown in Figure 1). At that level, it has a marked influence on the performance of the engine. Read more
The Boom SST engine problem, Part 2
By Bjorn Fehrm
Subscription required
Introduction
December 01, 2016, ©. Leeham Co: Boom Technology and Virgin Atlantic plan to offer supersonic business class passenger traffic over the Atlantic. We covered the number of challenges that this poses in recent articles. The most difficult challenge is finding a suitable engine.
We started the investigation into a suitable engine in the last article. A Supersonic Transport Aircraft (SST) needs an engine which is very different from the latest crop of high-performance airliner engines.
Figure 1. Boom Technologies Boom Mach 2.2 airliner with 45-seater. Source: Boom
The air entering the engine intake at Mach 2.2 is taken from standing still to a speed of 450m/s within a fraction of a meter. This raises the air pressure and temperature more than the combined intake/fan/low compressor does for a modern turbofan. The result is that the core’s high pressure compressor must adapt; it can’t have a high compression ratio (then things get too hot).
Add to that, that the engine must be slender. It can’t have a wide fan and therefore high by-pass ratio because the supersonic drag of such large engines would be too high.
Summary:
- The SST engine must be based on a core with a low pressure ratio.
- Such cores are no longer available in modern airliner engines.
- One must use cores from the military field of supersonic engines.
- We check what kind of engine can be constructed around such a core.
- Is the Boom SST mission then possible with an engine done with an existing core?
For Airbus and Boeing, it’s about Alabama, Alabama, Alabama
US Sen. Jeff Sessions (R-Alabama) is President-Elect Donald Trump’s choice for US Attorney General. He’s a close ally of Airbus. Photo via Google images.
Nov. 29, 2016, (c) Leeham Co.: When it comes to the prospect of imposing trade sanctions or retaliatory tariffs on Airbus for airplanes ordered by US customers, the European manufacturer has some advantages over Boeing few people apparently have thought about.
Alabama, Alabama, Alabama
One is called Alabama. It’s where Airbus is producing A320 family members for US customers.
Alabamans voted by 1.76-to-1 for Donald Trump. Sixty-three percent to 35%.
Donald Trump tapped Sen. Jeff Sessions of Alabama to be his Attorney General. Sessions was one of the first in Congress to endorse Trump. He served as an advisor throughout the campaign.
Sessions is a big supporter of Airbus.
Sen. Richard Shelby, the other Alabama Senator in Congress, is also a big supporter of Trump. And of Airbus.
It’s highly likely that Sessions and Shelby will bend Trump’s ear in favor of not levying tariffs on Airbus planes.
Airbus, Boeing claim victory in today’s WTO ruling over Washington State tax breaks
- Airbus claims “knockout blow.”
- Boeing claims “complete victory.”
- WTO Summary of findings and ruling.
- All the WTO documents are here.
- Opinion: No sanctions will be levied on Airbus or Boeing.
- Seattle Times on why nothing will happen with this ruling.
- Airbus YouTube: WTO disputes in 3.5 minutes.
- Scott Hamilton’s column in Forbes.
Nov. 28, 2016, © Leeham Co.: Airbus claims that in a huge blow to Boeing and Washington State, the World Trade Organization (WTO) ruled today that the $8.7bn tax subsidy package Gov. Jay Inslee and the state Legislature approved for the 777X program is a “prohibited subsidy.”
This is the most onerous finding of illegal subsidies under WTO rules, and one that is rarely determined.
Boeing said the WTO “today rejected virtually all of the European Union’s challenges to the Washington state tax incentives” and declared a “complete victory.”
Full Airbus, Boeing statements on WTO ruling
Nov. 28, 2016: Here are the full statements from Airbus and Boeing about the WTO ruling today finding Boeing received prohibited subsidies from Washington State for the 777X development:
Pontifications: A fresh perspective at Boeing Commercial is sorely needed
By Scott Hamilton
Nov. 28, 2016, © Leeham Co.: Boeing last week named an outsider, Kevin McAllister, as the chief executive officer of Boeing Commercial Aircraft (BCA).
I think this has the potential to be an invigorating move.
McAllister comes to BCA from his position as CEO of GE Aviation Services.
I don’t know McAllister and have no opinion whether he will be good, bad or mediocre. But I do like the idea of bringing an outsider in to run BCA. (My insider favorites were Stan Deal and Beverly Wyse.)
Here’s why.
The Boom SST engine problem
By Bjorn Fehrm
Subscription required
Introduction
November 28, 2016, ©. Leeham Co: We covered Boom Technology’s and Virgin Atlantic’s plans to offer supersonic business class passenger traffic over the Atlantic in recent articles. In the first article, we focused on the problem areas that Boom technology must master.
The most difficult area is to find a suitable engine for the aircraft. Engines for long-range supersonic flight are quite different animals than the normal subsonic airliner engine. We will go through why the engines are different and give an example of how such an engine could look.
Figure 1. Boom Technologies Boom Mach 2.2 airliner with 45 seaters. Source: Boom.
By creating a concrete example of an SST engine for an aircraft the class of the Boom SST, it will be possible to understand if Boom’s claim that suitable cores are available holds water, and how realistic is it to make an SST engine from these.
Summary:
- An SST engine is very different from a modern engine for a long-range airliner.
- A high-performing long-range engine for a normal airliner has a high bypass and pressure ratio.
- A high-perfoming long-range SST engine for a supersonic airliner has a low bypass and pressure ratio.
- Intakes and exhausts on subsonic engine nacelles are simple.
- Intakes and exhausts on supersonic engine nacelles are not simple.
- Considering all these factors, we will design an engine system for the Boom SST to get a deeper understanding of the challenges involved.
Norwegian, others have vision; US airlines don’t
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Introduction
Dec. 5, 2016, © Leeham Co. Last weeks’ approval by the US Department of Transportation of a license for Norwegian Air Shuttle to operate long-haul, low-cost service to and from the US drew immediate fire from labor unions over anticipated US job losses.
Iceland’s Loftleider Airlines, one of the first trans-Atlantic low-cost carriers. Photo via Google images.
But their view is too narrow.
It means more jobs for Boeing and its supply chain, which are also heavily unionized. It means benefits to US exports.
But overlooked is the next evolution in long haul travel that starts next year.
Summary
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Posted on December 5, 2016 by Scott Hamilton
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