Leeham News and Analysis
There's more to real news than a news release.
Bjorn’s Corner: Turbofan engine challenges, Part 4
By Bjorn Fehrm
November 18, 2016, ©. Leeham Co: In our series on modern turbofan airliner engines, we will now go deeper into the compressor part. Last week, we covered the fundamentals of compressors. As compressors and turbines use the same principles, we also covered the fundamental working principles of turbines.
We also described that compressors are temperamental parts, which can protest to wrong handling with violent “burps” (burst stalls with the combustion gases going out the front of the engine) or end up in a rotating stall where it simply stops working.
Figure 1. Stylistic cross section of a two shaft turbofan with both axial and radial compressor. Source: GasTurb.
Turbines, on the other hand, are your robust companions. Aerodynamically they just work, albeit more or less efficiently dependent on what one asks them to do (mechanically it can be very different; we recently saw a turbine disintegrate with large consequences on an American Airlines Boeing 767 in Chicago). More on the turbines later.
In the GasTurb cross section of a two shaft turbofan in Figure 1, the engine has both an axial and a radial compressor. We will consider why engine designers combine these two for certain engine types. Read more
Bjorn’s Corner: Turbofan engine challenges, Part 3
By Bjorn Fehrm
November 12, 2016, ©. Leeham Co: In our trip through a modern turbofan airliner engine and its technologies, we looked last week at the engine intake and the fan. We now continue with the compressor parts.
As compressors and turbines use the same principles (but in opposing ways), we will look at these principles this week and how their roles in the engine create their special characteristics.
Figure 1. Stylistic cross section of a three-shaft turbofan with section numbers. Source: GasTurb.
As before, to make things concrete, we use a GasTurb simulation of a Rolls-Royce Trent XWB 84k engine to look at practical data when needed. As before, I have no specific knowledge about the engine and will not use any data outside what is public information.
The GasTurb cross section of a three-shaft turbofan is shown in Figure 1. We will examine the sections between station numbers (22) and (3) and (4) and (5) in the general discussion of compressors and turbines. We will then look at some data for common compressors. Read more
Bjorn’s corner; Turbofan engine challenges; Part 2
By Bjorn Fehrm
November 04, 2016, ©. Leeham Co: We will now start to go through a modern turbofan airliner engine and look at the technologies which are used and what are their technical challenges. We will start today with the engine intake and the fan.
To make things concrete, we will use a GasTurb simulation of a Rolls-Royce Trent XWB 84k engine. This will provide us with realistic example data for the different parts of the engine. I want to stress that all values are assumed as typical for such an engine. I have no specific knowledge of the Trent XWB and will not use any data outside what is public information.
Figure 1. Stilistic cross section of a three-shaft turbofan with section numbers. Source: GasTurb.
The GasTurb cross section of a three-shaft turbofan is shown in Figure 1. We will use the station numbers in the figure to navigate the engine and the data from the simulation to understand modern airline engines and their typical data. Read more
Engine industry clamoring for road back
By Bjorn Fehrm
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Introduction
October 13, 2016, ©. Leeham Co: The airline engine industry is like a ticking bomb. Over the years, a business practice of selling the engines under manufacturing cost and planning to recover costs and make a profit on the aftermarket developed. This goes back decades.
The practice was fostered by fierce competition over the engine contracts for aircraft which offered alternative engines. The losses of the engine sales could be made up later by selling spare parts and services at high margins.
Figure 1. Trent 7000 from Rolls-Royce. Source: Rolls-Royce.
These “jam tomorrow” practices have several implications. The engine industry is now confronted with these and wonder how it could put itself in such a bind. How to handle these and what is the way back?
Summary:
- High competition in engine sales forced ultra high discounts for the up-front engine sale.
- Aftermarket schemes was created that should recover profits over spare parts and services.
- But these maintenance practices create all sorts of problems in the used engine market.
- The engine industry now wants to return to more normal business practices. But how do they find the way back?
Bjorn’s Corner: The Chinese aircraft engine industry
By Bjorn Fehrm
October 07, 2016, ©. Leeham Co: In our Corners on East bloc aeronautical industries, we will now look at the Chinese civil aircraft engine industry.
The Chinese engine industry is closely modeled after the Chinese aircraft industry that we looked at last week. It is organized as divisions and later subsidiaries to the major aircraft companies. Contrary to the Chinese aircraft industry, it has had major problems in gaining the necessary know-how to start developing and producing its own designs.
The industry has built Soviet designs on license since the 1950s and only recently managed to present functional own designs, after many failures.
Russian-Chinese wide-body: Program responsibilities
By Bjorn Fehrm
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Introduction
September 29, 2016, ©. Leeham Co: We will now finish our series about the Russian-Chinese wide-body with looking at who will have what role in the program.
Figure 1. Concept for new wide-body airliner. Source: United Aircraft.
As we described in the initial article, “Background and outlook,” Russia and China have vastly different competencies when it comes to making a state of the art wide-body aircraft.
Russia has made airliners since the 1930s, including wide-body jets. China did not design its own jet aircraft (military or civil) until the mid-1980s. Most of the aircraft produced still today in China have their origin in Russian designs.
At the same time, we saw in the article about the market demand for the aircraft that the Chinese market is 90% of the home market. This makes for China demanding important parts of the aircraft’s production, and China has the money to invest in production facilities.
All this will influence how different parts of the project will be shared between Russia’s United Aircraft Corporation (UAC) and Commercial Aircraft Corporation of China (COMAC).
Summary:
- Russia and China enter the wide-body project with widely different knowledge bases.
- Russia has long time knowledge on how to develop and produce aircraft and their engines.
- China on the other hand has the market for the aircraft.
- China also know a lot about serial production and have money to invest. Read more
Weekly Analyst Synopsis: Rolls, Boeing and leasing companies
Sept. 28, 2016: This week’s aerospace analyst research synopsis looks at Rolls-Royce. aircraft leasing companies and the implications to supply-and-demand, and the Iran Air order clearance by the US for Boeing.
No sanctions will be levied on Airbus and Boeing in WTO dispute
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Now open to all readers.
Introduction
Sept. 26, 2016, © Leeham Co.: It’s hazardous to use the word “never,” but the US and European Union will never impose trade sanctions or tariffs on Airbus or Boeing airplanes.
No sane president would do so. (Cue Donald Trump.) It would start a devastating trade war and the collateral damage on innocents in the Airbus-Boeing illegal subsidies disputes would be severely harmed.
Summary
- US tariffs on Airbus aircraft and EU tariffs on Boeing aircraft would hurt engine makers, suppliers—innocents in the illegal subsidy disputes.
- Some key customers order from Airbus and Boeing. Tariffs on one or the other company risk alienating these customers.
- Sanctions/tariffs permitted on other companies, industries.
- Canada, Brazil never imposed sanctions in Bombard-Embraer violations.
Russian-Chinese wide-body: Aircraft performance
By Bjorn Fehrm
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Introduction
September 19, 2016, ©. Leeham Co: In Part 4 of the article series, we put together an assumed complete Chinese-Russian wide-body aircraft with fuselage, wing, engines, etc. It is now time to understand what kind of performance that can be expected, given the data we have from the wide-body partners, Russia’s United Aircraft Corporation (UAC) and the Commercial Aircraft Corporation of China (COMAC).
Figure 1. Concept for new widebody airliner. Source: United Aircraft.
We will combine these data with the ones we have deduced as plausible to fill the gaps, given the time frame and technology level that UAC and COMAC intend to use.
Out will come a first estimate of what kind of performance such an aircraft can have in terms of efficiency and payload versus range capability.
Summary:
- We can use all the data we have gathered to make a first estimate of the efficiency of the Russian-Chinese wide-body.
- We also have enough information to do a first payload-range diagram and to compare that with the diagram for Boeing’s 787-9.