The „war of words“ on the GLG website

The GLG website is a big fairground for those who wish to tell the audience what they think about the two engines currently in development for the new or re-engined narrowbodies. I found the most of the claims that are being made in the recent “expert contributions” as just plain wrong or as misunderstandings.

Take the contribution “CFM International LEAP-X Engine Anything But A Derivative” as an example. This article is nothing as plain anti-rhetoric against P&W’s GTF and pure PR for the LEAP-X, but has nothing to do with an objective analysis.

Both engines feature (or will feature) a complete new core, both will have a 2 stage HPT.

One can guess that the HPC of the LEAP-X is a scaled-down and advanced version of the GEnx HPC and the same is true for the HPT. New materials further improve the performance of the core, as less cooling is needed as with conventional materials. What we don’t know is if the HPT would basically need more cooling air than the GEnx HPT as it probably runs even a little hotter. This is unusually for a narrowbody engine, as maintenance costs play a significant role here in the equation.
The core of the GTF is all new and was already tested successfully (if you want to believe the PR from P&W).
Now take a look at the comparison the author makes:

He states that the baseline thrust of the GTF starts at 21,000lbs – wrong as the MRJ engine starts at about 15,000lbs for the MRJ70. The engine for the CSeries starts at 21,000lbs and the proposed engine for the A320NEO covers the full range of the thrust needed for the Airbus narrowbody family up to 33,000lbs. This engine would have an up-scaled core from the CSeries engine, as the NG34 (or TECH-X) from GE would get a scaled-down core from LEAP-X.

If the author would be right when he writes that the baseline thrust for LEAP-X would be 30,000lbs (for the C919), CFM would have a hard time to sell that engine to Boeing, as the B737 does not need more than 27,300lbs today and a downrated engine would be sub-optimal for the B737. So CFM might have to come up with a separate engine (maybe with a smaller core) to cover Boeing’s thrust needs.

If one claims that the GTF architecture is forty years old as the author does, he has to call the architecture of the LEAP-X at least forty years either, as it is nothing less but nothing more than a 2 spool turbofan.

SFC reduction for both is in the same range. CFM gives a certain number, P&W gives something like a range, but in the end they will end in the same area – it’s coming down to physics.

Please, bloggers, experts and who-else-writes-about engines: let’s do not just play CFM vs. P&W, just as others always play A. vs. B. on the aircraft side. It might be fun when you start but soon turns boring.

Engine battle

Ok, here is my first real post...

There is an engine battle going on for a while now - but it is also a PR battle, a battle of words, whatever you want to call it: it's CFM's LEAP-X vs. P&W's GTF (Geared Turbo Fan, for beginners).
For example there is is a debate going on, which of the two engines is "just" a derivative and which of them is a revolutionary concept.
There are the ones who say that the GTF is a thirty year old concept - there are the ones who say the LEAP-X is just another step in the CFM line-up of all the CFM56 engines and the TECH56 programme.
There are the ones who call the GTF the winner of the battle, well before the first engine in the test programme is fired up.
There are the ones who call LEAP-X the winner, as it features (read: will feature) revolutionary materials, but first engine to test is also well ahead of us.
As long as we all do  not have all the facts in our hands, let's just wait: the first GTF engine that one day will power the Bombardier CSeries will have it's first run in the coming weeks. Of course, we will not get the real-data from P&W, but in the next months and years (aerospace is a long-term business by all means) and as also the LEAP-X will come along, the truth about the winner (if there is one) will come to light.
In the meantime I will try to shed some light on the two different concepts from my very own perspective.


New blog-kid on the block

Hi everyone,

here is another aero-related blog. As the number is growing almost every day and many of them I found are ill- or at least poor-informed I decided to start my own one, concentrating, but not limited, to aero (turbo)engines.
To be clear: there are many good-informed blogs and websites (think of flightblogger and Scott Hamiltons Comments), but there are also many who just write about something they read about with no further background knowledge.
But how can I claim that others are not well informed? Well, in short: because I am ;-)
Ok, let's say I am - to my knowledge - at least better informed as I am directly "related" to the industry and have access to information they do not have.
To rely on information from the press and from press material can never lead to an objective conclusion, as every company involved in the business will only show their view of things.
I will try to give an inside view of things that are so interesting in "our" business.
I will try to be as honest as possible with all the information I have.
But I won't to go so far to tell any company secrets...

Have fun!