By Bjorn Fehrm
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Introduction
December 15, 2016, ©. Leeham Co: In our article series around the engine for a Boom SST, we established the thrust requirements for the engines in Part 3.
To fulfill these requirements, we have now designed four different engines. Three are of the type that Boom says it is considering, an engine that is based on an existing core.
Figure 1. Boom Technologies Boom Mach 2.2 45 seat airliner. Source: Boom.
We based these around a military core with the right characteristics for a low-to-medium bypass SST engine. The fourth engine is a custom-designed straight turbojet, very similar to the engine that propelled the only operational SST, the Concorde.
We will use the reference turbojet to understand the difference to a turbofan in this application and why the selection of an engine for a SST follows different rules than for a normal airliner.
Summary:
- Supersonic flight requires engines with low frontal areas and low mass flows.
- Should the engine be designed as for a normal airliner, the inlet drag would be prohibitive.
- The engine also must have a low pressure ratio core; otherwise the energy of the fuel is wasted on non-productive work.
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Deferrals grow as airlines fight to keep bottom line
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Introduction
Jan. 09, 2017, © Leeham Co.: Airlines have deferred or are thinking about deferring more than 400 airplanes in the near term, a review of decisions and deliberations that have been made during the last 12 months.
LNC tracked announcements last year of deferrals and statements by airlines that they are thinking about doing so.
We began identifying macro-level issues last week in our posts about emerging concerns for the 787 and LNC’s Outlook for 2017.
Reasons vary widely for the deferrals, these reports indicated. Low oil prices. Slowing economies. Declining financial results. Worries about two of the three top Middle Eastern carriers. A capital squeeze in China. Pressure on long-haul carriers from the emerging sector of low cost, long-haul airlines. Preserving capital expenditures to keep the bottom line in the black.
Today we detail the deferrals we tracked.
Summary
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1 Comment
Posted on January 9, 2017 by Scott Hamilton
Airbus, Airlines, Boeing, Bombardier, Delta Air Lines, Leeham News and Comment, Pratt & Whitney, Premium, Qatar Airways, Rolls-Royce
777 Classic, 787, A380, Airbus, airlines, Boeing, Bombardier, Emirates Airlines, Goldman Sachs, Qatar Airways
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.
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31 Comments
Posted on January 6, 2017 by Bjorn Fehrm
Airbus, Bjorn's Corner, Boeing, CFM, Comac, CSeries, E-Jet, GE Aviation, Irkut, Pratt & Whitney, Rolls-Royce, United Aircraft
737 MAX, A320NEO, A330neo, A350-1000, Airbus, Boeing, Bombardier, CFM, Comac, CSeries, Embraer, Pratt & Whitney, Rolls-Royce
Pontifications: Embraer, contrary to others, looks to momentum in 2017
By Scott Hamilton
Jan. 3, 2017, © Leeham Co.: Airbus, Boeing and Bombardier look toward 2017 as a bit of a punk year, as detailed in our Look Ahead for subscribers only. Not so by Embraer.
In an exclusive interview, John Slattery, the president of Embraer Commercial, said EMB will gain “momentum” this year. This is at a time where sales at the other three of the Big Four OEMs are expected to slow off an already slow 2016.
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30 Comments
Posted on January 3, 2017 by Scott Hamilton
Airbus, Boeing, E-Jet, Embraer, Emirates Airlines, Pontifications, Rolls-Royce, Sukhoi
737-900ER, 777, 787-10, 787-8, A330-900, A350-900, A380, Airbus, Boeing, Delta Air Lines, EJet, EJet E2, Ejet-E1, Embraer, John Slattery, Northwest Airlines, Rolls-Royce, Scope clause, SSJ100, Sukhoi
2017: the year ahead
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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
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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
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.
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5 Comments
Posted on December 16, 2016 by Bjorn Fehrm
Bjorn's Corner, CFM, GE Aviation, Pratt & Whitney, Rolls-Royce
CFM, CFM56, GE Aviation, Geared Turbo Fan, IAE, Pratt&Whitney, Rolls-Royce
The Boom SST engine problem, Part 4
By Bjorn Fehrm
Subscription required
Introduction
December 15, 2016, ©. Leeham Co: In our article series around the engine for a Boom SST, we established the thrust requirements for the engines in Part 3.
To fulfill these requirements, we have now designed four different engines. Three are of the type that Boom says it is considering, an engine that is based on an existing core.
Figure 1. Boom Technologies Boom Mach 2.2 45 seat airliner. Source: Boom.
We based these around a military core with the right characteristics for a low-to-medium bypass SST engine. The fourth engine is a custom-designed straight turbojet, very similar to the engine that propelled the only operational SST, the Concorde.
We will use the reference turbojet to understand the difference to a turbofan in this application and why the selection of an engine for a SST follows different rules than for a normal airliner.
Summary:
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4 Comments
Posted on December 15, 2016 by Bjorn Fehrm
Future aircraft, Rolls-Royce
Boom, EJ200, Rolls-Royce, SST
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
6 Comments
Posted on December 9, 2016 by Bjorn Fehrm
Airbus, Bjorn's Corner, CFM, GE Aviation, Pratt & Whitney, Rolls-Royce
CFM, CFM56, GE Aviation, Rolls-Royce, Trent XWB
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:
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1 Comment
Posted on December 8, 2016 by Bjorn Fehrm
Boeing, Future aircraft, Rolls-Royce
Boom SST, Concorde, Rolls-Royce, SST
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
13 Comments
Posted on December 2, 2016 by Bjorn Fehrm
Airbus, Bjorn's Corner, Boeing, CFM, GE Aviation, Pratt & Whitney, Rolls-Royce
Airbus, Boeing, CFM, CFM56-5, GEnx-1B, GEnx-2B, Rolls-Royce
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:
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2 Comments
Posted on December 1, 2016 by Bjorn Fehrm
Future aircraft, GE Aviation, Pratt & Whitney, Rolls-Royce
Boom SST, CFM, GE Aviation, GEnx-1B, GTF, LEAP, Pratt & Whitney
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