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Boeing's Sutter: 737 replacement timing depends on engines
Boeing Senior Advisory Group members, from left, John Roundhill, Bob Davis and Joe Sutter meet with reporters on June 22. (Aubrey Cohen/seattlepi.com)
For all of the focus on use of composite materials in Boeing's 787 Dreamliner and, less so, the 747-8, most of the airplanes' increased efficiency comes from engines, and engines control the timing of replacing the workhorse 737.
At least, that's the view of Joe Sutter – the legendary Boeing engineer and father of the 747 and 737.
"The new 747 is about two-thirds engine, one-third aerodynamics" in terms of efficiency improvements, Sutter said last month in a meeting of Boeing Commercial Airplanes' Senior Advisory Group, of which he's a member.
"The 787, I'm guessing about 60 percent or so is engine."
Looking at the 737 replacement, he said: "What's going to decide when it's going to be has nothing to do with Boeing or the customer.
It's when will the engine people come up with a fifth- or sixth-generation engine.
When they're ready, I think Boeing will be ready. What year is that? I don't know."
Boeing and Airbus executives have said they will decide this year whether to replace their single-aisle mainstays or equip them with new, more-efficient engines.
Part of the pressure for the decision is coming from upstart new competitors, such as Bombardier's CSeries and Comac's C919.
Last month, Boeing Chairman, President and CEO Jim McNerney suggested Boeing would probably replace the 737 if it could develop a new aircraft with enough improvement for airlines by 2020.
Why does it depend on engines?
Looking at aerodynamics, "the industry has reached a technology plateau to some extent," Sutter said.
Engine makers say they can offer double-digit improvements in fuel efficiency on the 737 and Airbus A320, with greater improvements on new aircraft.
That's within the historical range of what it takes to make a new airplane sell, according to Senior Advisory Group member John Roundill.
"You will find from generation to generation that the improvement in fuel efficiency or passenger seat mile economics, whatever metric you want to use, will improve 10 to 20 percent," he said.
One engine possibility that has been getting attention is an open-rotor design, which promises increased fuel efficiency.
But open-rotor engines have to go on the back of the fuselage, limiting options for enlarging the aircraft, Sutter said.
"She won't stretch, so you've got a one horse shape."
Safety's a bigger problem, he said.
"If I were the chief engineer on that airplane, the one that would scare the hell out of me is the first day I lose a blade and lose an airplane.
The business of safety is foremost in airplane design, and the open rotor has a serious problem that way."
But Roundhill noted that, as engines have been getting bigger, so has the weight penalty for putting shrouds around them.
Another idea that group members dismissed was a reincarnation of Boeing's Sonic Cruiser concept, which would fly just below the speed of sound, but wouldn't be as efficient as a new slower airliner such as the 787, which eventually supplanted it in Boeing's plans.
"If the technology improves you could move the Sonic Cruiser to be more efficient than it was, but you could always do a mach .85 aircraft that would be 20 percent more efficient," Roundhill said.
Sutter said the Sonic Cruiser was devised "by people who had been smoking marijuana," although he later revised that to cocaine.
One non-engine way to improve efficiency is through the larger wings that composites enable, Roundhill said. "So then you say, 'Where am I going to park these airplanes with the bigger (wing)spans?'"
That's one obvious way in which selling airplanes isn't just about having the jet with the fanciest technology.
After criticizing Airbus for "always touting technology," Sutter said: "Technology does not sell airplanes.
The guy who comes up with the right airplane for the market is going to get the biggest share of the buy. ...
I think that's where Boeing has an advantage over the other guy."
For example, Boeing developed the 747 with 10-abreast seating in mind for airlines and an eye toward the freighter market, Sutter said.
"They can land with a full load of payload, they can open the nose door and side door, unload the whole payload, reload the whole payload, and that's quicker than refueling the airplane."
On the 777, Roundhill said: "There were a few airlines that really helped us establish that cross section.
They were working their business class, what it would look like, their coach class, the flexibility they wanted in the interior and we changed it as a result of the airlines input.
We added 5 inches to the cross section from our preliminary layups."
Jim Albaugh created the Senior Advisory Group after taking over as president and chief executive of Boeing Commercial Airplanes last year, at a time when many saw the company as losing its traditional focus on engineering.
Albaugh has changed that perception by example, group member Ron Ostrowski said.
"He sits in all of our meetings, throughout all of those meetings," Ostrowski said. "When the 787 started to fly, they invited several of us in to monitor the flight readiness for the first flight.
We spent a whole week doing that with the whole team. And it was always our prerogative to speak up whenever we felt it necessary. And the reaction was always very positive."
Boeing does need to keep a closer eye on its outsourced engineering work, Sutter said.
"Engineers tend to drift off and do their own thing if you let them. The only way you maintain discipline is to watch them like a hawk. And that hasn't always happened at Boeing."