Boeing 737 MAX
|Boeing 737 MAX|
|Artist's conception of the Boeing 737 MAX|
|Role||Narrow-body jet airliner|
|National origin||United States|
|Manufacturer||Boeing Commercial Airplanes|
|Developed from||Boeing 737 Next Generation|
The Boeing 737 MAX is a family of aircraft being developed by Boeing Commercial Airplanes. The new family is based on the Boeing 737 Next Generation family, which it is to replace. It will be the fourth generation of the 737 family. The primary change is the use of the larger and more efficient CFM International LEAP-1B engines. The airframe is to receive some modifications as well. The 737 MAX is scheduled for first delivery in 2017, 50 years after the 737 first flew. Boeing has firm orders for the 737 MAX totaling 2,099 as of June 2014.
Since 2006, Boeing has discussed replacing the 737 with a "clean-sheet" design (internally named "Boeing Y1") that could follow the Boeing 787 Dreamliner. A decision on this replacement was postponed, and delayed into 2011.
In 2010, Airbus launched the Airbus A320neo with new engines to improve fuel burn and operating efficiency; it was initially planned to enter service by mid-2016, later moved up to October 2015. The decision was met with positive reaction by many airlines, which began making major orders for the improved aircraft. Pressure from the airlines for more fuel efficient aircraft caused Boeing to pursue upgrading the 737 with new engines instead of the new Boeing Y1 design. On August 30, 2011, the company's board of directors approved the 737 MAX project. Boeing predicted that the 737 MAX will provide a 16% lower fuel burn than the current Airbus A320, and 4% lower than the Airbus A320neo. Boeing expects the 737 MAX to meet or exceed the range of the Airbus A320neo. The first 737 MAX aircraft is scheduled to be delivered in 2017. In December 2013, Boeing stated that a recent internal audit forecasts a 14% lower fuel burn than current 737NG series aircraft.
The three variants of the new family are the 737 MAX 7, 737 MAX 8 and 737 MAX 9 which are based on the 737-700, -800 and -900ER, respectively, the best-selling versions of the 737 Next Generation family. Boeing has stated that the fuselage lengths and door configurations from the Boeing 737 Next Generation family will be retained on the 737 MAX variants. On July 23, 2013, Boeing announced it completed the firm configuration for the 737 MAX 8.
Initially, the customers for the 737 MAX were not disclosed, except for American Airlines. On November 17, 2011, Boeing released the names of two other customers – Lion Air and Aviation Capital Group. At that time, Boeing reported 700 commitments from 9 customers for the 737 MAX. Then on December 13, 2011, Southwest Airlines announced they would be the launch customer for the 737 MAX with a firm order of 150 aircraft and 150 options. By December 2011, Boeing had 948 commitments and firm orders from 13 customers for the 737 MAX.
Improving fuel efficiency
Boeing's design improves fuel efficiency in a number of ways. The most significant improvements are to the wing, the interface of wing and engine, and the use of winglets. The 737NG's wing creates transonic shock waves on the inboard wing at the interface with the CFM-56-7B engine. The 737 MAX wing's integration of the Leap engine's nacelle reduces this drag by 0.5%. In addition, the Leap engine is mounted higher and further forward of the wing's leading edge than the CFM-56-7B is on the 737NG's wing.
A new type of wingtip device is to be introduced on the new 737 versions. Boeing designed the device to maximize lift specifically on airplanes with wingspans that fit Category C airport gates. The device is a direct descendant of the winglet designed for the McDonnell Douglas MD-12. Resembling a three-way hybrid between a blended winglet, wingtip fence, and raked wingtip, Boeing states that this new design should deliver an additional 1.5% improvement in fuel economy over the 10–12% improvement already expected for the 737 MAX. The fuel savings could be even higher if a laminar flow surface treatment being applied meets expectations. Boeing told Aviation Week and Space Technology that the 737-8 MAX with the new winglet can have a 1.8% better fuel burn than a blended winglet-equipped aircraft on flights of 3,000 nautical miles with 162 passengers. The advantage increases with flight length, but a short flight of 500 nautical miles has a 1% lower fuel burn with the aircraft flying at Mach 0.79.
Flight deck and flight controls
The manufacturer plans no major modifications in the flight deck as it wants to maintain commonality with the 737 Next Generation family. There will however be four new large format displays supplied by Rockwell Collins. These are 15.1-inch landscape LCD displays that will increase situational awareness and efficiency currently used on the 787 Dreamliner. Boeing also plans to add more fly-by-wire control systems to the 737 MAX family, although Albaugh said that changes would be "very minimal." Boeing has confirmed that fly-by-wire controls will be added to the spoilers.
Boeing spent most of 2011 evaluating two fan diameters of the CFM International Leap-1B engine: 66.1 in (168 cm) or 68.1 in (173 cm), both of which would require few changes to the landing gear to maintain a 16.9 in (42.9 cm) ground clearance beneath the engines. Boeing Commercial Airplanes CEO Jim Albaugh stated the larger fan diameter would produce less fuel burn, but because it is bigger, it produces more drag and is heavier, and would need more extensive airframe changes.
Both fan diameters are an increase from the 61.8 in (157 cm) CFM56-7B engine on the Boeing 737 Next Generation. The updated airliner is also expected to feature external nacelle chevrons for noise reduction, similar to those on the 787 and 747-8. While the smaller Leap-1B engine would have a lower bypass ratio and higher specific fuel consumption (SFC) than the baseline 78 in (198 cm) Leap-X and 80.7 in (205 cm) Pratt & Whitney PW1100G engine options for the A320neo, the smaller engine will weigh less and create less drag on the airframe. The 66.1 in (168 cm) engine integrated on the airframe would offer an SFC improvement of 10–12% over the current 737NG CFM56-7B engine. Industry sources report that assessments are underway to revise the tail cone, natural laminar flow nacelle and a hybrid laminar flow vertical stabilizer for additional fuel burn decrease and drag reduction.
In November 2011, Boeing announced the selection of the 68.1 in (173 cm) fan diameter. Because of the larger fan diameter compared to the 737 Next Generation family, the nose landing gear will have to be lengthened by 6–8 inches (15–20 cm) to maintain the required ground clearance. Firm configuration for the 737 MAX is currently scheduled for 2013. On May 17, 2012, Boeing announced a further modification to the fan diameter with an increase to 69.4 inches (176 cm). The larger fan will be paired with a smaller engine core than previously identified as part of a series of minor design changes before the final configuration is set in mid-2013.
There will also be a new digital regulator for the engine bleed air systems which should improve its reliability.
- 737 MAX 7 – Replacement for the 737-700 and 737-700ER
- 737 MAX 8 – Replacement for the 737-800; longer fuselage than the -700/MAX 7
- 737 MAX 9 – Replacement for the 737-900ER; longer fuselage than the -800/MAX 8
|737 MAX 7||737 MAX 8||737 MAX 9|
|Seating capacity||140 (1-class, typical)
126 (2-class, typical)
|200 (1-class, high density)
175 (1-class, typical)
162 (2-class, typical)
|220 (1-class, high density)
192 (1-class, typical)
180 (2-class, typical)
|Seat pitch||29 in (74 cm) (1-class, high density)
32 in (81 cm) (1-class, typical)
36 in (91 cm) & 32 in (81 cm) (2-class, typical)
|Overall length||110 ft 5 in (33.7 m)||129 ft 8 in (39.5 m)||138 ft 4 in (42.2 m)|
|Wingspan||117 ft 10 in (35.9 m)|
|Overall height||40 ft 4 in (12.3 m)|
|Cruising speed||Mach 0.79 (522 mph, 842 km/h)|
|Maximum take-off weight||159,400 lb (72,303 kg)||181,200 lb (82,191 kg)||194,700 lb (88,314 kg)|
|Cargo capacity||966 ft³ (27.3 m³)||1,555 ft³ (44 m³)||1,826 ft³ (51.7 m³)|
|Range fully loaded||3,800 nmi (7,038 km)||3,620 nmi (6,704 km)||3,595 nmi (6,658 km)|
|Engine (× 2)||CFM International LEAP-1B|
|Fan tip diameter||69.5 in (1.77 m)|
The 737 MAX has firm orders totaling 2,115 as of July 2014.
- Related development
- Aircraft of comparable role, configuration and era
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