With airlines facing rising fuel costs and weight-based costs equating to nearly 30% of an airline's operating costs, this optimised 68-inch fan design will offer a smaller, lighter and more fuel-efficient engine to ensure we maintain the current advantage we have over the competition," Boeing 737 chief programme engineer John Hamilton said.
In a teleconference with the media on the same day, Boeing 737 chief programme engineer John Hamilton explained that the weight of the airplane itself also drives the thrust requirement of the engine and therefore it plays a role in the engine fan size decision as well.
"The 737-900ER is 10,000 lbs lighter than the A321.
If you look at the operating weight per seat, our -900ER is nearly 50 lbs lighter per seat and so there is a much better structurally efficiency that goes into the 737 design than into the Airbus design," Hamilton
"Weight drives a lot of cost into an airline's operation.
In addition to the fuel that it takes to lift that weight off the ground and carry it to the air, it also plays a part into maintenance cost and landing cost as well as the thrust requirement for the engine.
And so Airbus on an A321 has to put 32,000 or 33,000 lbs of thrust on there versus -900ER it is only 26,000 lbs or 27,000 lbs, so a lot lower thrust requirement on the 737 programme.
"Today our engine is 7 inches smaller than the Airbus and yet we have a lower operating cost than the Airbus product.
Again this gives back to the structural efficiency of the airplane and the higher thrust requirement and the higher maintenance cost that the Airbus engine requires.
As we size up the equivalent inch on the [737 MAX], Airbus is going to have to size up to 78 [inches on the A320neo's CFM Leap engine] to provide the same sort of efficiency," Hamilton
"Both the fuel saving that comes from the engine as well as the drag associated with that engine as it flies through the airspace.
And so you can think of a 78-inch engine is kind of like your meck truck driving down the road and a 68 [inch engine] is being a lot leaner and less drag on the engine and also the weight of the engine offsets the benefit as well," Hamilton
"So when you look at drag, fuel efficiency, and the weight the 68-inch fan is really the right optimum solution for the 737 airplane going forward," Hamilton
Airbus disputed this claim, with the spokeswoman at its North American unit Mary Anne Greczyn saying "if a smaller fan engine were to generate the appropriate level of efficiency, we could have easily incorporated that, since we are not constrained as our competitor".
"The A320neo family", she
added, "is designed to benefit from the aircraft's inherent advantage".
has opted to lengthen the nose landing gear of the 737 MAX to allow "better optimisation" to take place, which is likely to necessitate the relocation of the narrowbody aircraft's electronics/equipment (E/E) bay without a nose blister fairing.
"We can put a 68-inch fan on the airplane without changing the nose gear but we allowed our designers to remove that constraint to see if they could further optimise the engine on the airplane and we believe there is a little better optimisation that will occur when we allow the nose gear to float up a little bit," Boeing 737 chief programme engineer John Hamilton said.
"Today the nose gear [on the Next-Generation 737] is actually slightly tilted down and so today's jetways, today's airstairs are not going to be affected by the change," Hamilton
"We understand the nose gear design and we will be finalising that in the months ahead," Hamilton
According to sources Boeing is favouring an 8-inch extension in the nose landing gear, despite the ongoing evaluation on a 6 to 8 inches lengthening.
We know we could create a little more laminar flow in the back of the airplane and so it is really changing some of the aero-line back there," Boeing 737 chief programme engineer John Hamilton explained.
has offered a 737 MAX featuring 777-styled raked wingtips to its customers, which will improve payload/range capabilities of the airplane and a marginally better fuel burn.
"Things like the winglets are in our trade space and we will continue to work with API
and doing studies internally to understand where can we get a little more efficient on that," Hamilton
"Just an economic of view, we went with the raked wingtip on the P-8 more because of the mission it flies, not necessarily because of its efficiency, because we had to keep certain characteristics in check," Hamilton
"We are also taking a look at some minor system changes, one of them is fly-by-wire spoilers so going to fly-by-wire spoilers put some as it saves weight from the airplane and it will improve the production flow in the factory and it allows us to improve stopping performance with the airplane as well," Boeing
737 chief programme engine John Hamilton
"The system that we are looking at to put on the MAX is really kind of a 757-type system architecture and simplifying it down, it does not require as much redundancies as if you are going to put fly-by-wire on your primary flight controls like ailerons, elevators and so the weight impact of going to a totally fly-by-wire system is what is needed to do just for the spoilers.
It is going to be a weight saving for us," Hamilton
"We will strengthen the wing for that higher load from the engine, there might be some localised structuring strengthening we need to do with the fuselage, but pretty minimal there, we talked about fly-by-wire spoilers, those are going on, there are some minor system changes that associated with the engine change that we need to make, the engine computer essentially the software that drives that we are going to need to change," Hamilton
Coupled with the 777-styled raked wingtips, the partial fly-by-wire system is going to redistribute loads inwards and could enable Boeing
to increase the maximum take-off weights (MTOWs) of 737 MAX 9 to make it a closer 757 replacement.
"The 737 today can fly roughly about 95% of the mission that the 757 flies today so the 737-900ER is a really good airplane for that.
Now are we going to get the range that the 757 has?
We are talking with our customers but we are not going to get out the 4,000 nautical miles range and the payload the 757 flies today," said Hamilton, Boeing spokeswoman Karen Crabtree said "the MTOW for MAX 7, 8 and 9 is currently being studied to meet market requirements" while clarifying "minor system changes such as fly-by-wire spoilers offer weight savings for the airplane".
"We will continue to work with CFM and continue to customise the engine that is unique to the 737 and really optimised the engine so you get the right bypass ratio, the right core thrust that serves the 737 and it is customer-based as well as it comes while maintaining the remarkable maintenance advantage and reliability that the CFM engine has today," Boeing 737 chief programme engineer John Hamilton said.
"We are working closely with CFM
and understanding what technologies are available today that are proven that we can use with the engines to optimise it, including the number of blades you need, the size of the core, the configuration of the core.
"What is going to be available to support the entry into service and so if there are technologies there that we can take advantage of CFM and Boeing
agree that make sense, we will consider that," Hamilton
As the 737 MAX is still some time before its detailed configuration is finalised in 2013, Boeing
will continue to evaluate different options for the airplane and choose the options that bring the most value to its customers.
And there is no doubt that the 737 MAX will become popular, as airlines strive to slash costs in light of the persistently high oil prices.
"We expect several hundred more commitments soon.
Some customers they are waiting to hear more about what the configuration and the performance of the airplane," Boeing 737 chief programme engineer John Hamilton said.