Physics Challenge Boeing’s Minimalist Approach to 737 Max

AIN Air Transport Perspective » April 16, 2012
Boeing 737 Max 8
Boeing 737 Max designers have integrated the engines with the wing to produce aerodynamic lines similar to those seen on the Dreamliner. (Photo: Boeing)
April 16, 2012, 10:55 AM

Boeing engineers appear to have kept themselves busy refining the design of the 737 Max since the company announced its intention to re-engine the ubiquitous 737NG with CFM Leap-1B turbofans. Apparently, the laws of physics have challenged Boeing’s ambition to minimize airframe and systems changes, judging by the extent to which it now expects to refine the design to achieve the fuel burn and performance targets it set for itself when it launched the Max last August.

Changes to the design announced just last week include aerodynamic improvements to the aft body section, on which designers have extended the tail cone and thickened the section above the elevator to improve the steadiness of airflow. Boeing expects the modifications to eliminate the need for vortex generators on the tail and result in less drag.    

As expected, in an effort to maintain about the same engine ground clearance of the NG, Boeing plans to use a new engine pylon and strut, along with an eight-inch nose-gear extension and a change to the nose-gear door design. Meanwhile, designers have integrated the engines with the wing to produce aerodynamic lines similar to those seen on the Boeing 787.

A change to the flight control system involves a switch from mechanical to fly-by-wire spoilers to save weight, while an electronic, rather than pneumatic, bleed-air system allows for increased “optimization” of the cabin pressurization and ice protection systems, resulting in better fuel burn.

Of course, Boeing will also need to strengthen the main landing gear, wing and fuselage to accommodate the increase in loads due to the larger engines, which have a fan diameter of 68 inches. Boeing also continues to conduct wind tunnel testing on a possible revision to the wing tips. The company said it will continue to conduct aerodynamic, engine and airplane trade studies as the design team endeavors to finish its work by mid-2013.

“Any new technology incorporated into the Max design must offer substantial benefit to our customers with minimal risk for the team to pursue it,” said Michael Teal, chief project engineer and deputy program manager. “On the 737 Max we are following our disciplined development process and continue to work on an airplane configuration that will provide the most value for our customers.”

Boeing promises the Max will deliver a 10- to 12-percent fuel-burn improvement over today’s 737 and a 7-percent per-seat operating cost advantage over the Airbus A320neo.

 

 

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eric
on April 17, 2012 - 2:23am

Well, it took Boeing a long time to actually use fly by wire instead of criticising it, as they did all this wasted time. As the saying goes if you can't beat them join them, meaning Airbus

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Joseph
on April 19, 2012 - 7:26pm

They only went to fly by wire spoilers. Still primary controls are mechanical.

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keesje
on April 20, 2012 - 6:01am

It think there might be some doubts if the MAX can be as good as Boing claims it will be.

"Boeing promises the Max will deliver a 10- to 12-percent fuel-burn improvement over today’s 737 and a 7-percent per-seat operating cost advantage over the Airbus A320neo."

Few people believe the last bold claim. Sales don't seem to support it.

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Larry Walters
on April 20, 2012 - 6:57am

Many new players in the Fly By Wire group are not confident in their teams to be able to handle the new challenges. You could always take the bull by the horns and go get the people you need from other companies to make them part of your team, oops sorry HR would never let you do that. HR runs businesses and is the boat anchor to progress.

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