GTF for B737MAX?

Rumors are spilling over and over since the ISTAT Americas conference in March that Boeing is seriously looking at the P&W GTF as a second engine option in addition to the LEAP-1B for the B737MAX. Aspire Aviation has a long article about the ongoing optimisation of the MAX here and Scott Hamilton is quoted in an article by the New Mexico Business Weekly here. A reason for these rumors seems to be the lack of confirmed orders for the MAX so far. There are only three customers who have ordered the MAX, all others only delivered commitments to the Boeing Headquarter so far. Sure, the year is long, so there is enough time for Boeing to convert the commitments to firm and credible orders, especially as Boeing might be keen to make a similar splash with the MAX at Farnborough as Airbus did with the Neo at Le Bourget last year. But as now there are these rumors about a possible second engine, the committed customers might want to wait and see if there is some truth behind them. So firming up the commitments before there is a final word from Boeing (or P&WA) in either way might be a challenge.
Scott Hamilton expects a decision in the next months - that could also coincide with Farnborough...

Doubts about MAX

Last month I wrote a short entry about Ryanair's Michael O'Leary and what his thoughts are about the B737MAX. Well,  when he talks about aircraft, it barely has to do with physics and what the aircraft can or can not do - it always has more to do with the price for his next deal...
But when the "Godfather of Aircraft Leasing", Steven Udvar-Hazy

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: