Narrowbody and Widebody engine developments, Part 2

By Bjorn Fehrm

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Introduction

April 19, 2018, © Leeham News: In an article last week, we discussed the reason the new narrow-body engines are catching up to the fuel consumption of the wide-body engines.

Today we dig a bit deeper into the efficiency changes of the different engines and discuss which parameter changes have caused what changes in engine efficiency.

We will use our engine modeling software GasTurb to analyze what happens in a Turbofan when we change certain parameters.

Summary:

  • The engine’s Core or Thermal efficiency changes with Turbine Entry Temperature (TET).
  • To fully utilize such an increase in efficiency we need to adapt the overall design of the engine.

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Narrowbody and Widebody engine developments

By Bjorn Fehrm

Subscription Required

Introduction

April 12, 2018, © Leeham News: In an article yesterday about Long-Haul LCC costs we observed how the new Narrowbody engines are catching up to the fuel efficiencies of the Widebody engines.

Traditionally the Widebody engines were the efficiency leaders. The Narrowbody companions were designed to be durable rather than efficient.

Figure 1. Cut through of the Narrowbody LEAP engine. Source: CFM

We use the engine modelling software GasTurb to understand why this catching up of the Narrowbody engines has happened.

Summary:
  • The new Narrowbody engines for Airbus’ A320 series and Boeing’s 737 MAX are close in specific fuel consumption to the new Widebody engines.
  • We use the GasTurb engine modelling software to find the root cause of this change.

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Pratt & Whitney’s Indian trouble

By Bjorn Fehrm

March 14, 2018, ©. Leeham Co: India’s Directorate General of Civil Aviation (DGCA) grounded Airbus A320neos equipped with Pratt & Whitney GTF engines with faulty compressor seals Monday.

Affected are eight A320neos of Indigo airlines and three A320neos of GoAir. The Indian groundings are unusual as they go beyond the directives of EASA and FAA for the problem.

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Bjorn’s Corner: Aircraft engines, sum up

By Bjorn Fehrm

April 14, 2017, ©. Leeham Co: We’ve been talking engines on Fridays since October 2016. The Corners covered several areas, from technologies to operations.

And we could go on and dig deeper. But we will move on.

Before we go, we sum up what we have learned in the 24 Corners around airliner Turbofans.

Figure 1. Principal picture of a three-shaft wide-body turbofan. Source: GasTurb.

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Bjorn’s Corner: Aircraft engine maintenance, Part 3

 

By Bjorn Fehrm

March 17, 2017, ©. Leeham Co: In the last Corner,  we showed graphs of the yearly flight hours for engines on single-aisle aircraft. Now we will deduce the market for engine overhauls from these graphs.

These will show which engines generate a maintenance volume that is interesting for engine overhaul companies and which engines are niche.

Figure 1. Principal picture of a direct drive turbofan. Source: GasTurb.

Based on the market size, we will then go through how an engine is maintained when new, mature and at end-of-life.

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Bjorn’s Corner: Aircraft engines maintenance, Part 2

 

By Bjorn Fehrm

March 10, 2017, ©. Leeham Co: Last week we started the series how airline turbofans are maintained. We described the typical work scopes and what the intervals were for different single-aisle engines.

Before we can describe the engine maintenance market we must get a feel for the market size for different engine types.

 

Figure 1. Principal picture of a direct drive turbofan. Source: GasTurb.

We will start with understanding the single-aisle engine maintenance market. Read more

Bjorn’s Corner: Aircraft engine maintenance, Part 1

By Bjorn Fehrm

March 3, 2017, ©. Leeham Co: We will now go through how airline turbofans are maintained. First, we will describe the typical work which is performed, then look into the markets for engine maintenance.

In the markets for engine maintenance, we will look at who the players are, how they are related to the engine OEMs and why the market dynamics are very different between engines for single-aisle aircraft and wide-bodies.

Figure 1. Principal picture of a direct drive turbofan. Source: GasTurb.

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Bjorn’s Corner: Turbofan engine challenges, Part 4

 

By Bjorn Fehrm

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.

gasturb-graph

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

CSeries out of London City Airport, Part 2. UPDATED 2017.01.24

By Bjorn Fehrm

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Introduction

This article, which was published on the 14 November, has been updated with new information from Bombardier. The range of the CS100 from London City airport has increased due to improved performance from the aircraft and a new engine version with more thrust, the PW1535G engine.

November 14, 2016, ©. Leeham Co: In the last article about operating the Bombardier (BBD) CS100 from London City Airport (LCY), we could see that the runway is about half the length of an international airport’s runways. This will have a significant impact on the Take Off Weight (TOW) that can be used when commencing a route from London City.

aerial_view_of_london_city_airport_2007

Figure 1. London City airport, housed in the docklands of London’s east end. Source: Wikipedia.

The manufacturers have data in their aircraft brochures that state that one should be able to takeoff with e.g. the CS100 at Maximum Take Off Weight (MTOW) from a runway which is 1,463m/4,800ft long. London City Airport’s runway is 1,508m/4950ft long, so then things should be fine?

No, the figures from the OEMs is the planning figure for actual runway used and London City airports usable take-off Runway is given as 3,934ft. In addition there is 394ft stopping distance available.

To understand how this can be used required a bit of information that we did not have at the time of writing the original article. Some of the information we used was not up to date and we did not use the strongest engine available (PW1535G) when analyzing if an operator could fly direct between New York from London City.

Bombardier came to our help and we have now been able to update the data with which to feed our performance model. This shows among other things that it’s possible to operate a direct connection between London City airport and New York, given that the number of passengers (the payload) is restricted to around 50 passengers or below.

We have revisited the two cases, SWISS European operations from London City and how would a direct operation London-New York work. You find the updated article below.

Summary:

  • London City Airport puts special requirements on the aircraft serving it.
  • It puts stringent requirement for takeoff and approach/landing.
  • We use new information and our performance model to present what routes can be served with a CS100 from the London City Airport.

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Bjorn’s Corner: Turbofan engine challenges, Part 3

By Bjorn Fehrm

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.

trent-xwb-model-stations_

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