Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- The Boeing 767 Cross Section, Part 1 November 24, 2022
- Movie Review: Devotion November 21, 2022
- China will accelerate development of its commercial aerospace sector November 21, 2022
- Bjorn’s Corner: Sustainable Air Transport. Part 46. eVTOL comparison with helicopter November 18, 2022
- The economics of a 787-9 and A330-900 at eight or nine abreast November 16, 2022
Bjorn’s Corner: Turbofan developments in 2017
By Bjorn Fehrm
January 06, 2017, ©. Leeham Co: Before we finish of our series on airliner turbofan technology, let’s spend this Corner on what will happen on the airliner engine front during 2017.
While there is no totally new engine that comes into the market during 2017 there are a number of new variants of existing engine families that will be introduced.
Figure 1. GasTurb principal representation of a three shaft turbofan like our reference Rolls-Royce Trent XWB. Source: GasTurb.
If we start with the engines for regional/single aisle aircraft and then climb the thrust scale, we will cover the engines in climbing thrust class.
Bjorn’s Corner; Turbofan engine challenges, Part 7
By Bjorn Fehrm
December 16, 2016, ©. Leeham Co: After the turbine comes the engine’s exhaust system. This is where the thrust characteristics of the engine are formed. It is also the environment that defines the back pressure for the fan and turbines. It’s therefore more high-tech than one thinks.
For the very high bypass airliner engines of tomorrow, the common fixed bypass exhaust of today (Station 18 in Figure 1) will not be acceptable. Variable exhaust areas will have to be introduced.
Figure 1. GasTurb principal representation of a three shaft turbofan like our reference Rolls-Royce Trent XWB. Source: GasTurb.
On engines that function in high supersonic speed, it gets really complex. Not only is the exhaust area variable, it must have a dual variation exhaust, a so-called Con-Di nozzle.
Bjorn’s Corner; Turbofan engine challenges; Part 6
By Bjorn Fehrm
December 08, 2016, ©. Leeham Co: We have now come to the turbine in our trip through a modern turbofan. The turbines make up the rear of the engine, before the propelling nozzle.
The turbines are the workhorses in the engine. They take the energy released by the fuel in the combustion chamber and convert it to shaft hp to drive the fan or compressors.
Figure 1. GasTurb principal representation of a three-shaft turbofan like our reference Rolls-Royce Trent XWB. Source: GasTurb.
The hotter they can operate, the better. They can then generate more hp on a smaller size turbine. The temperature of the gas entering the high pressure compressor is one of the key parameters of a gas turbine. It dictates the power efficiency of the core and how much work it can perform to drive the fan and the compressors. Read more
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
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
Bjorn’s Corner: The Engine challenge
By Bjorn Fehrm
October 21, 2016, ©. Leeham Co: In our Corners on East bloc aeronautical industries, we could see that the hardest part to master in a new civilian airliner is the engine.
Both new airliners from Russia and China (Irkut MC-21 and COMAC C919) start their lives with Western engines.
Why is this so? What are the challenges that make engines harder to create than aircraft?
LEAP-1C which will be standard engine on COMAC C919. Source: COMAC.
We will spend several Corners on the main reasons that airliner engines are harder to do than aircraft. Read more
Engine industry clamoring for road back
By Bjorn Fehrm
Subscription required.
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?
2017: the year ahead
Subscription Required
Introduction
Jan. 3, 2017, © Leeham Co.: The New Year is here and it doesn’t look like a good one for commercial aerospace, if measured against previous outstanding years.
There are some troubling signs ahead, piling on to a slowdown in orders from last year that didn’t even reach a 1:1 book:bill.
This year looks to be worse than last. Airbus and Boeing will give their 2017 guidance on the earnings calls this month and next. Bombardier and Embraer earnings calls are a ways off, when each will provide its guidance.
But LNC believes the Big Two in particular will be hard pressed to hit a 1:1 book:bill this year and may even struggle to match 2016 sales.
Boeing’s year-end order tally comes Thursday. Airbus’ comes on Jan. 11.
Summary
Read more
1 Comment
Posted on January 3, 2017 by Scott Hamilton
Airbus, ATR, Boeing, Bombardier, CFM, Comac, CSeries, E-Jet, Embraer, Etihad Airways, Farnborough Air Show, GE Aviation, Irkut, Leeham News and Comment, Middle of the Market, Mitsubishi, Pratt & Whitney, Premium, Rolls-Royce, Sukhoi
Airbus, Boeing, Bombardier, CFM, Comac, Embraer, GE Aviation, Irkut, Mitsubishi, Pratt & Whitney, Rolls-Royce, Sukhoi