Definitive LEAP1-B fan diameter!(?)

Yesterday at the ISTAT Americas conference Mike Bair from Boeing revealed that the LEAP-1B fan diameter for the B737MAX now stands at 68.4". When Boeing and CFM for the first time officially announced a fan diameter for the LEAP1-B in November 2011 (Press Release), it was 68", 7" more than the fan diameter of the CFM56-7BE of the current B737NG.
In the meantime there were news in different but reliable media (LeehamNews, aspire aviation) that the diameter went up to 68 3/4" or 68.5". So now it is 68.4" - what does that tell us?

1. Size matters - although Boeing denies that. Well, of course there is a sweet spot for every aircraft/engine combination, as Scott Hamilton writes in a recent column, so you can't go everywhere with fan size. But apparently CFM still tries to maximize the fan diameter of the LEAP-1B so it just fits under the wing and to get the best possible fuel burn for the aircraft. That means that 68" is not the sweet spot, but that is is somewhere higher.
2. It means that the definition of the engine is probably still not finished yet. If the fan size changes, this potentially changes everything else - at least if you want to maximize efficiency of the whole engine. In turn that means that there is still a lot work for Boeing to define to pylon and the pylon/wing interface.

So stay tuned for the next MAX fan diameter...

Airbus A320Neo Engine Race

It is just another "intermediate result" in a race that could last for 20 years or maybe more (and we are just at the beginning): but now that the PW1100G-JM scored another two sales (TransAsia for six aicraft plus six options and GoAir for 72 aircraft), the Geared Turbo Fan is in the lead over the LEAP-1A again. The LEAP engine scored big during the Paris Air Show, taking the lead by a wide margin then after announcing a design change with a seventh LPT stage and a larger fan diameter. With these changes CFM claimed to be as good if not better than the GTF in fuel burn. That claim was dismissed by John Leahy last week when he said that the GTF would be about 1.5% better in fuel burn.
The GTF has now announced orders for 488 aircraft, the LEAP-1A has announced orders for 465 aircraft.

UPADTE:  CFM just annouced that ALAFCO choose the LEAP-1A for the 35 additional A320neo orders. So LEAP-1A is in the lead again:
LEAP-1A:         500
PW1100G-JM: 488

Airbus: GTF better than LEAP...

I obtained an interesting note from Forecast International, itself claiming to be the "Leading Provider of Aerospace, Defense, Electronics and Power Systems Intelligence. Here it is:

Ryanair and B737MAX

Not often I tend to agree with the outspoken Ryanair CEO Michael O´Leary, nicknamed by the twitter community with @MichaelOhReally. But when he recently talked about the B737 MAX, I had to agree with him. He said that he has been impressed by the fuel burn improvement the A320neo promises to deliver, but he is not impressed by the B737 MAX and said that the fuel born improvement is inferior.
Particularly he fears that the heavier CFM LEAP-1B engines and the subsequent heavier airframe will offset the better SFC, when compared to the CFM56-7B(E).
Meanwhile I had the opportunity to read the latest

Norwegian goes the American way...

That was a surprise this morning - it was long rumored that Norwegian is one of the airlines that already committed for the B737MAX (100 firm orders plus 100 purchase rights in addition to a follow-on order for 200 B737-800NG), in that case the -8 model. But that they also would order the A320neo (MoU for 100 aircraft plus 50 purchase rights) could not have been expected.
There are two possible explanations that come to my mind as reasons for that decisions to go away from a single-type fleet:

1. They went the AA way (of negotiating), meaning they negotiated with both Airbus and Boeing until they got a deal from both they could not resist to close them both.
2. Their anticipated growth is too large that one of the OEM's could deliver aircraft fast enough to satisfy that growth.

On the other hand it is a little bit discussable if a mixed fleet of B737-800NG and B737MAX-8 would be a single-fleet type anyway. The engines (CFM56-7BE and LEAP-1B) do not have anything in common and Boeing itself talks about 85% commonality between the NG and the MAX. So Norwegian would have had a two-type fleet anyway until the last -800NG would have been phased out. Now that Norwegian gets aircraft from both Airbus and Boeing the last -800NG will be phased out earlier so that the (at that scale) marginally higher costs through having a two-type fleet will be (probably) more than offset by the lower fuel costs.

The next interesting question will be the engine choice for the A320neo. Although the selection of the LEAP-1A to complement the LEAP-1B on the MAX-8 fleet would be the most logical choice, they maybe also go the AA way and buy from both engine manufacturers, like AA did it recently for their A319 (CFM56) and A321 (V2500). So the PW1100G could come into play - the factsheet that Norwegian provided with their press release shows the fan diameter of the PW1100G (81"), but that does not necessarily say anything...