Boeing has made a series of design decisions to update the 737 MAX design in order to optimize the new-engine 737 variant's performance, from...

Boeing has made a series of design decisions to update the 737 MAX design in order to optimize the new-engine 737 variant’s performance, from the time the 737 MAX family enters service in 2017.

“The 737 MAX is on track to deliver substantial fuel savings to customers starting in 2017,” says Beverly Wyse, vice president and general manager, 737 program. “We’ve made several design decisions that support the performance targets for the MAX and evolve the Next-Generation 737’s design within the scope of the 737 MAX program.”

Boeing says its new family of re-engined 737s – the 737 MAX 7, 737 MAX 8 and 737 MAX 9 – builds on the strengths of the Next-Generation 737

The design decisions made by the manufacturer for the Boeing 737 MAX family include:

Aft-body aerodynamic improvements: The tail cone will be extended and the section above the elevator thickened to improve steadiness of air flow. This eliminates the need for vortex generators on the tail, according to Boeing. These improvements will result in less drag, giving the aircraft better performance;

Engine installation: The new CFM International LEAP-1B engines (which probably will have either a 68-inch or a 69-inch fan diameter) will be integrated with the wing similar to the aerodynamic lines of the Boeing 787 engine with its wing. A new pylon and strut, along with an 8-inch nose gear extension, will maintain similar ground clearance to today’s Boeing 737NG family while accommodating the larger engine fan of the LEAP-1B compared with the CFM56-7B, which powers the 737NG family. The nose gear door design is altered to fit with this revision; and

Flight control and system updates: The flight controls will include fly-by-wire spoilers, which will save weight by replacing a mechanical system. The 737 MAX also will feature an electronic bleed air system, allowing for increased optimization of the cabin pressurization and ice protection systems, resulting in better fuel burn.

Boeing has named its new, re-engined 737 family the 737 MAX and the capacity-equivalent of the 737-800 (the highest-selling version of the 737NG family) is to be the 737 MAX 8

Other minor changes to the Boeing 737 MAX family include strengthening the main landing gear, wing and fuselage to accommodate the increase in loads due to the larger engines.

Boeing will continue to conduct aerodynamic, engine and airplane trade studies as the team works to optimize the design of the aircraft by mid-2013.

“We also continue to do work in the wind tunnel to affirm the low- and high-speed performance of the 737 MAX design,” says Michael Teal, chief project engineer and deputy program manager for the 737 MAX program.

“Based on design work and preliminary testing results, we have even more confidence in our ability to give our customers the fuel savings they need, while minimizing the development risk on this program,” adds Teal.

A possible revision to the wing tips on the MAX also is being tested in the wind tunnel to see if this new technology could further benefit the aircraft.

The Boeing 737 MAX 9, the biggest model in the new, re-engined 737 MAX family, corresponds to the 737-900ER model in the 737NG family

“Any new technology incorporated into the MAX design must offer substantial benefit to our customers with minimal risk for the team to pursue it,” says Teal. “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 claims airlines operating the 737 MAX will see a 10 to 12 percent fuel-burn improvement over today’s most fuel-efficient single-aisle aircraft and a 7 per cent operating cost per-seat advantage over tomorrow’s competition.

The competition, Airbus and Bombardier, disagree with Boeing’s analysis – particularly Bombardier, since its CSeries airframe design is all-new, while Boeing’s 737 MAX design is a derivative of the 45-year-old 737 airframe design. Airbus’ A320neo airframe is a slightly modified derivative of the late-1980s A320 design.

Airbus is offering two engine choices for the A320neo family: the Pratt & Whitney PurePower PW1100G geared turbofan (the launch engine for the A320neo) and the CFM International LEAP-1A.

Bombardier is offering the PurePower PW1500G geared turbofan for the CSeries, the PW1500G being the first version of the highly promising PW1000G geared-turbofan family to enter service. The initial CS100 version of the CSeries family is scheduled to enter service in late 2013.

To date, the Boeing 737 MAX family – the 737 MAX 7, 737 MAX 8 and 737 MAX 9, the versions respectively sized to correspond with today’s 737-700, 737-800 and 737-900ER – has orders accumulated and commitments for more than 1,000 aircraft from 16 customers worldwide.