Boeing 737MAX

Raked wingtips are a feature on some Boeing airliners, where the tip of the wing has a higher degree of sweep than the rest of the wing. The stated purpose of this additional feature is to improve fuel efficiency and climb performance, and to shorten takeoff field length. It does this in much the same way that winglets do, by increasing the effective aspect ratio of the wing and interrupting harmful wingtip vortices. This decreases the amount of lift-induced drag experienced by the aircraft. In testing by Boeing and NASA, raked wingtips have been shown to reduce drag by as much as 5.5%, as opposed to improvements of 3.5% to 4.5% from conventional winglets.[13]

The 737RE was characterized as a ‘paper’ airplane. Indeed, we have learned that Boeing is still massaging design details. It remains to be decided if Boeing will go with a 70-inch fan that will require more work statement for the airframe, including changes to the nose gear, or if it will go with a 66-inch fan that will eliminate the need for nose gear modifications, reduce the R&D costs but will trade off fuel efficiency slightly and be noisier than the 70-inch fan.

17: The inches Boeing needs to maintain underneath the re-engined 737's nacelle as to not collide with taxiway lighting.

61: The inches in the fan diameter of the CFM56-7BE that powers today's Next Generation 737.

63: The maximum number of inches in the Leap-X fan diameter that will require no change to the 737's main landing gear.

70: The inches in one potential Leap-X fan the company is evaluating for the re-engined 737.

8: The inches the 737's nose gear needs to be lengthened to carry a 70in fan to achieve 12-15% improvement in fuel burn.

78: The inches in the fan diameter of the Leap-X1A that will power American's A320neo.

Boeing has delivered its first Next Generation 737 with updated CFM56-7BE engines, part of an on-going development plan to provide a 2% improvement in fuel burn.
China Southern took delivery of the 737-800 last week with the -7BE engine, now standard on all 737s and includes improved airfoils in the high and low pressure turbines along with new engine cooling techniques. The engine also features fewer parts to help lower maintenance costs.
Boeing introduced a drag reduction package earlier this year that included improved wing control surfaces, revised wheel well fairings and a new anti-collision light, contributing to an approximate .6% improvement in fuel burn.
The updated engine and its updated nozzle will deliver a further 1.2% fuel burn improvement.
An improved ECS exhaust modification, which will bring shave an additional .2% in fuel burn, is expected to improve the total fuel burn by 2% when all the elements are integrated together by 2012.
Flight testing with the modifications began in November 2010 and analysis will take place to "quantify the final benefit to customers," said Boeing.
"We continue to review performance flight test data and collect delivery data," said John Hamilton, vice president and chief project engineer - 737 programme.
Once all the changes are incorporated into the 737, Boeing expects that the narrowbody will be approximately 7% more efficient than the first models delivered in 1998.
The introduction of the updated -7BE engine is separate from the airframer's plan unveiled 20 July to re-engine the 737 by the middle of the decade with a CFM Leap-X powerplant, touting a further 10 to 12% improvement in fuel burn.