In my imagination, one business case for this concept is a long range passenger plane with fewer passengers than the current jumbos. A 737 with the range of 747.
I remember the B747SP, a shortened Jumbo with extra fuel, to fly from NY to Tehran in 17 hours. A month ago I read about an extended range 787 that was to fly between London(UK) and Perth(Aus) in 17 hours. There seem to be problems at the airport of Perth.
CFM certificates C919 engine ahead of first flight
- 21 DECEMBER, 2016
- SOURCE: FLIGHTGLOBAL PRO
CFM International has certificated the integrated propulsion system (IPS) for the Leap-1C with the European Aviation Safety Agency and the US Federal Aviation Administration to clear one of the key regulatory hurdles for launching the Comac C919 airliner into commercial service.
Consisting of the engine, nacelle and thrust reverser, the Leap-1C IPS marks the third version of CFM’s latest single-aisle engine family to achieve certification. The Airbus A320neo, powered by the Leap-1A and the rival Pratt & Whitney PW1100G, entered service earlier this year. CFM also received certification for the Leap-1B for the Boeing 737 Max, which remains in development.
“It has been an incredible year for the LEAP program, culminating in the certification of the third model in this engine family,” says Allen Paxson, executive vice-president for CFM.
Comac launched the Leap engine development programme in 2009, with an original entry into service target of 2016. Delays have shifted first delivery to Chinese customers back two years. Comac plans to begin flying the first C919 test aircraft by the end of this year.
The certification milestone comes exactly seven years after Comac announced the selection of the Leap-1C engine for the 130-200 seat airline family.
The Leap-1C shares identical turbomachinery with the Leap-1A engine for the A320neo, differing only in the items that interface with components on the C919 airframe.
Congratulations
and say that Chinese engine technology is so backward even C919 wouldn't use it 
It won't be long somebody would say China hasn't inovated yet because C919 uses foreign engine
the business case for this is not very good. airlines use single aisle for sub-3000 nm routes because they are optimized for efficency in the 1000 to 2000 nm range. Airlines can pack a lot of people in all these shorter sub-6 hour flights. Anything longer, 29 inch pitch is just way too painful. You can pack a lot of people in on the 9-across 787, 9-across 350 and 10 across 777. If airlines can sell all the seats, then cost per passenger mile will be better than the single aisle plane. The major advantage for something like A321neo is that it can achieve comparable cost to B787 on sub-3000 nm routes as long as it packs the passengers in at tight spaces and it has much better turn around time. So you can use such planes for longer thin route like what a lot of US airlines do with east coast to Western Europe with B757. Anything further, a single aisle will have to dedicate a whole lot more space for storing fuel. On top of that, single aisles don't have crew rest built in so they have to block off business class seat for them. You can't install the fancy business class and first business class seat as you do on a B777. Just check out those 4 across business class seat on B77W aircraft and you would know what I mean.
You can't reduce weight by enlarging the wings unless you drastically reduce structural enforcing beams within them in which case you'll have to reduce the amount of cargo since you have less structural strength in the wings.
Making the conceptual design inferior compared to 787.