I saw this article about the latest design changes to the CFM LEAP engine. I described what I think about the seventh LPT stage and the larger fan diameter in my last blog entry. New to me in this article is, that CFM claims that the LEAP core would run at the same temperatures - at least turbine entry temperatures - than the CFM56.
Hmm, let's start with pure physics. The LEAP engine will have an OPR of 50 at top of climb. The CFM56-5B has an OPR of 35.5 at the highest (33klbf) thrust setting.
Make it easy and consider the Fan, the LPC and the HPC as one big compressor. The formula to get the compressor exit (or burner entry) temperature is:
T2=(1/etac)*(T1*(P2/P1)^(0.4/1.4)) with P2/P1 being the OPR in this case and etac being the compressor efficiency.
CFM says that the turbine entry/burner exit temperature stays the same, they do not say anything about the burner entry temperature. But to get the highest efficiency, the burner exit temperature (T3) should be
T3=(T2^2/T1), thus being independent from the OPR.
So let's consider that the ratio of T3/T2 should be about the same. Then T2 should be the same, too.
What does that mean for the compressor efficiencies? Well, if T2LEAP and T2CFM56 should be the same, then from the first formula can conclude that:
((OPRLEAP)^(0.4/1.4))/((OPRCFM56)^(0.4/1.4))=etac(LEAP)/etac(CFM56)
Computed, you will see, that the compressor efficiency of the LEAP engine should be 10% higher than that of the CFM56.
Now, the GE90 compressor, on of the predecessors of the LEAP compressor, is thought to have an efficiency of 91%. Let's assume, the LEAP compressor, although considerably smaller, has the same efficiency (which is hard as the relative clearances are larger in a smaller compressor). Then the efficiency of the CFM56-5 compressor should stand at 90%*91%= 82% - if true, the engine would be a disaster.
So, something does not add up here. An engine with a pressure ratio of 50 can't run at the same core temperature as an engine with a 29% lower OPR - or you did something wrong in your basic layout of the engine.
6/22/2011
6/19/2011
LEAP-X striking back?
CFM said over the weekend that they have four announcements on every of the first four days of this years Paris Airshow regarding LEAP-X customers. It is not clear, whether these are all for the A320neo or some of them will also be for the C919, but apparently CFM is strongly coming back from behind and it remains to be seen if the PurePower GTF engine can hold it's No.1 position on the A320neo.
According to a Bloomberg report, SAS will order the LEAP-X for their 30 A320neo. A few days ago I expected them they will go with the GTF - apparently I was wrong and I will speculate about the reasons a little bit later.
But let us look at the possible reasons of this comeback: if you read the blog entry behind the first link of this, article, there are two interesting things to note: CFM just lately changed the design of the LEAP-X engine:
1. The fan diameter got larger, from 75" before to 78" now.
2. The LPT got an additional stage - now it has seven, just as the GEnx-1B for the B787.
Both changes are good for about 1% in SFC - each. Additionally, I guess CFM changed to size of the core and made it smaller, what could yield in another 0.5% in SFC.
On the other hand, the engine gets larger, produces more drag, gets added weight and the added LPT stage produces extra maintenance costs.
Because of the added drag and added weight, the fuel burn benefit will end up in the range of 1.5-2%. Operating costs could end up being somewhere between 1-1.5% better.
If you study this site, CFM now claims a 1% better fuel burn against the GTF. Is this credible: a few weeks ago, before the design changes were made official, Bernstein, AirInsight and others said (with obviously good knowledge about the situation), that LEAP-X would trail the GTF by about 3%.
So if CFM now claims to be better by 1%, then they probably project their best possible SFC without regarding any development risk. This is not engineering practice, but as it seems, CFM can convince quite a number of customers with that strategy.
Now to the story about SAS and why they might have turned to CFM:
First, they are a flying a lot of B737NG, thus having a number of CFM56 in their fleet and possibly a good relationship to CFM. A few weeks back they dedided to lease 2nd hand B737-700 and with that opting against the CSeries.
Easy question: who is most interested in CSeries failing in the marketplace:
1. Airbus
2. CFM
For that reason, I could see a campaign to fight all possible CSeries deals in a joint effort from Airbus und CFM. The litmus test for this thesis will be the CSeries' fate at Republic: if Republic now orders the A320neo with the LEAP-X and (sooner or later) cancels the CSeries, I would see this thesis is "proven". Also watch for Qatar...
The thriller just starts here!
According to a Bloomberg report, SAS will order the LEAP-X for their 30 A320neo. A few days ago I expected them they will go with the GTF - apparently I was wrong and I will speculate about the reasons a little bit later.
But let us look at the possible reasons of this comeback: if you read the blog entry behind the first link of this, article, there are two interesting things to note: CFM just lately changed the design of the LEAP-X engine:
1. The fan diameter got larger, from 75" before to 78" now.
2. The LPT got an additional stage - now it has seven, just as the GEnx-1B for the B787.
Both changes are good for about 1% in SFC - each. Additionally, I guess CFM changed to size of the core and made it smaller, what could yield in another 0.5% in SFC.
On the other hand, the engine gets larger, produces more drag, gets added weight and the added LPT stage produces extra maintenance costs.
Because of the added drag and added weight, the fuel burn benefit will end up in the range of 1.5-2%. Operating costs could end up being somewhere between 1-1.5% better.
If you study this site, CFM now claims a 1% better fuel burn against the GTF. Is this credible: a few weeks ago, before the design changes were made official, Bernstein, AirInsight and others said (with obviously good knowledge about the situation), that LEAP-X would trail the GTF by about 3%.
So if CFM now claims to be better by 1%, then they probably project their best possible SFC without regarding any development risk. This is not engineering practice, but as it seems, CFM can convince quite a number of customers with that strategy.
Now to the story about SAS and why they might have turned to CFM:
First, they are a flying a lot of B737NG, thus having a number of CFM56 in their fleet and possibly a good relationship to CFM. A few weeks back they dedided to lease 2nd hand B737-700 and with that opting against the CSeries.
Easy question: who is most interested in CSeries failing in the marketplace:
1. Airbus
2. CFM
For that reason, I could see a campaign to fight all possible CSeries deals in a joint effort from Airbus und CFM. The litmus test for this thesis will be the CSeries' fate at Republic: if Republic now orders the A320neo with the LEAP-X and (sooner or later) cancels the CSeries, I would see this thesis is "proven". Also watch for Qatar...
The thriller just starts here!
6/17/2011
Boeing 737 successor Part V
I swear that this is the last piece in that series - before the Paris Air Show!
A recent piece in Flightglobal as well as a blog entry from Scott Hamilton this week shows that inside Boeing there are diverging blocks: one wants a new airplane, the other wants to reengine the B737NG and it seems like a "put them all in one boat"-solution to do it both. With a A320neo family arriving from 2015 onwards and a hypothetic new model from Boeing arriving in 2019 or 2020, with the CSeries entering the market in late 2013 and probably another 5 abreast aircraft from Embraer arriving at the end of the decade, who then needs a reengined B737NG? And if the backlog is so big that there are filled delivery positions even in 2018 today with todays B737NG, a reengined B737NG would only get a handful of orders from customers which did not get a delivery slot from Airbus, Bombardier or Embraer before the Boeing NSA is available.
So doing both makes no sense if the NSA is really slated for around 2020 - but a later arrival, around 2025 could make sense, as the differentiation against the A320neo in terms of engine and aircraft technology and thus operating costs could be larger then. That thinking should behind when Albaugh (quote Flightglobal) "questioned whether such an aircraft would be "good enough with rising fuel costs and emerging environmental regulations" and whether it could stay in service for 50 years." (quote end)
In the meantime, a reengining would make sense and would give that reengined B737NG a life expectation of at least ten years. At last years european ISTAT conference I spoke with some appraisers about the (the not yet launched) A320neo and they said that it would need a production run of at least ten years - the same should be true for a 737NGneo.
A "mild" reengining, maybe even avoiding changes to the front landing gear, should not bind too many engineering resources and should put Boeing in the position to counter Airbus if they should announce any changes to the A350-1000 that would make that aircraft to a better competitor to the B777-300ER than before.
A recent piece in Flightglobal as well as a blog entry from Scott Hamilton this week shows that inside Boeing there are diverging blocks: one wants a new airplane, the other wants to reengine the B737NG and it seems like a "put them all in one boat"-solution to do it both. With a A320neo family arriving from 2015 onwards and a hypothetic new model from Boeing arriving in 2019 or 2020, with the CSeries entering the market in late 2013 and probably another 5 abreast aircraft from Embraer arriving at the end of the decade, who then needs a reengined B737NG? And if the backlog is so big that there are filled delivery positions even in 2018 today with todays B737NG, a reengined B737NG would only get a handful of orders from customers which did not get a delivery slot from Airbus, Bombardier or Embraer before the Boeing NSA is available.
So doing both makes no sense if the NSA is really slated for around 2020 - but a later arrival, around 2025 could make sense, as the differentiation against the A320neo in terms of engine and aircraft technology and thus operating costs could be larger then. That thinking should behind when Albaugh (quote Flightglobal) "questioned whether such an aircraft would be "good enough with rising fuel costs and emerging environmental regulations" and whether it could stay in service for 50 years." (quote end)
In the meantime, a reengining would make sense and would give that reengined B737NG a life expectation of at least ten years. At last years european ISTAT conference I spoke with some appraisers about the (the not yet launched) A320neo and they said that it would need a production run of at least ten years - the same should be true for a 737NGneo.
A "mild" reengining, maybe even avoiding changes to the front landing gear, should not bind too many engineering resources and should put Boeing in the position to counter Airbus if they should announce any changes to the A350-1000 that would make that aircraft to a better competitor to the B777-300ER than before.
6/16/2011
Some airlines can't wait for Paris
The official opening of the Paris Air Show is still four days away, but there are a few airlines who can't wait to announce their (A32Xneo) orders.
Cebu Pacific and GoAir both placed orders today.
Cebu Pacific (I did not even have that on my list yesterday) placed an MoU for 30 A321neo. They also firmed up options for 7 A320 (Classic). Cebu stated that with the A321neo they will be able to fly to destinations which cannot be reached with the A320 today, namely Northern Japan, Australia and India. They will outfit their A321neo's with 220 seats - I have not heard of any airline with such a dense seating in a A321. Air Berlin has 210 seats, Air France in the domestic market version 206 seats.
And then there is GoAir - for 72 A320neo. I had them on my list for Paris, but for a maximum of 70 - well, not too far off. GoAir is owned by the Wadia Group, a powerful conglomerate, and got a new CEO just a few days ago, the former Chief Revenue Officer from Air One (Giorgio De Roni), which was (more or less) forced to merge with the old Alitalia.
GoAir has 10 A320 in the fleet, with 10 more to come in the next two years. By then, with a fleet of 20 aircraft and after 5 years of operation, they can fly internationally.
Both airlines fleets are powered by the CFM56 today and both airlines gave no indication of engine selection yet. It remains to be seen if my assumption that the PW1100G has the better cards in the indian market. At least the planned first delivery date (2015) for GoAir's A320neo seems to indicate a GTF selection here.
Cebu Pacific and GoAir both placed orders today.
Cebu Pacific (I did not even have that on my list yesterday) placed an MoU for 30 A321neo. They also firmed up options for 7 A320 (Classic). Cebu stated that with the A321neo they will be able to fly to destinations which cannot be reached with the A320 today, namely Northern Japan, Australia and India. They will outfit their A321neo's with 220 seats - I have not heard of any airline with such a dense seating in a A321. Air Berlin has 210 seats, Air France in the domestic market version 206 seats.
And then there is GoAir - for 72 A320neo. I had them on my list for Paris, but for a maximum of 70 - well, not too far off. GoAir is owned by the Wadia Group, a powerful conglomerate, and got a new CEO just a few days ago, the former Chief Revenue Officer from Air One (Giorgio De Roni), which was (more or less) forced to merge with the old Alitalia.
GoAir has 10 A320 in the fleet, with 10 more to come in the next two years. By then, with a fleet of 20 aircraft and after 5 years of operation, they can fly internationally.
Both airlines fleets are powered by the CFM56 today and both airlines gave no indication of engine selection yet. It remains to be seen if my assumption that the PW1100G has the better cards in the indian market. At least the planned first delivery date (2015) for GoAir's A320neo seems to indicate a GTF selection here.
6/15/2011
Airbus A320neo order speculations
We are just days away from the Paris Air Show 2011 and every day there are more speculations about who will order how many aircraft at the show – and which ones.
The one thing that seems to be clear though is that the A320neo will get the bulk of orders.
So let me take part in the speculation game and start with the “Star” of the show:
Here is my guessing about who will order how many and the engine choice:
AirAsia | 150-200 | LEAP-X |
Republic | 40-80 | PW1100G |
Qatar | 30-50 | PW1100G |
GECAS | 50-100 | LEAP-X |
ALC | 25-50 | LEAP-X/PW1100G |
CIT | 20-30 | LEAP-X/PW1100G |
GoAir | 50-70 | PW1100G |
SAS | 30 | PW1100G |
In total we could see more than 600 orders/commitments for the A320neo family, with both engine makers getting their share of the market.
As for the LEAP-X it is crucial to get orders – GE seems to invest heavily in the AirAsia order, with GE becoming a sponsor of Tony Fernandes’ Formula 1 Lotus Team. Even if GE says that those two deals are complete separate…
As the CFM56 is AirAsia’s current engine choice, CFM was in the front runner position anyway. It remains to be seen, if Fernandes managed Leahy to convince him that a conversion of orders for the A320 ”Classic” can be transformed into A320neo orders and how many. And we will also see if this deal will be even larger than the yet-to-be-finalised order of 180 aircraft by Indigo.
Republic already placed a deposit in Toulouse
If Qatar
GECAS of course is the most natural LEAP-X customer. Nothing to add here...
After opposing the A320neo from the start, even Steven Udvar-Hazy seems to jump on the bandwagon now, as was reported earlier. I expect a split between LEAP-X and the PW1100G here, as well as from CIT.
GoAir obviously is in the market also for at least 50 A320neo. That seems a lot for an airline that has just 10 aircraft by now, but the fast growing Indian market is hungry for aircraft. The V2500 has a large customer base in India
SAS is looking for the A320neo, too, and I think this is the airline that is speculated to be the first neo-customer currently flying the B737NG. They have looked into the CSeries also, but decided to preserve cash by leasing 2nd hand B737-700. SAS did not rule out to order the CSeries later, so they could lean towards the PW1100G on the A320neo to have engine commonality (sort of), if they ever decide to order the CSeries.
There might be others to come forward and order more A320neo – who know. John Leahy understands how to do good marketing and always pull out a rabbit out of the hat…
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