737 MAX. Courtesy, Boeing

Boeing announced Wednesday it has made a series of design changes to the 737 MAX to further optimize the new-engine variant's performance.

The design improvements include an extended tail cone, an integrated engine/wing design similar to that of the 787, and fly-by-wire spoilers. A potential revision to the wing tips is also being considered and evaluated in wind tunnel tests.

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 and will result in less drag.

The CFM International LEAP-1B engines will be integrated with the wing similar to the aerodynamic lines of the 787 Dreamliner 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 737 while accommodating the larger engine fan. The nose gear door design will be altered to fit with this revision.

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

Other minor changes to the airplane include strengthening the main landing gear, wing and fuselage to accommodate the increase in loads due to the larger engines. Boeing also said it will continue to conduct aerodynamic, engine and airplane trade studies to optimize the design of the airplane 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," said Michael Teal, MAX chief project engineer and deputy program manager.

Boeing says the MAX will provide 10%-12% fuel-burn improvements over today's most fuel-efficient narrowbodies.

Boeing has more than 1,000 MAX 1,000 orders and commitments from 16 customers, including launch customer Southwest Airlines (ATW Daily News, Dec. 14, 2011).