A specially configured Boeing 737-800 meant to test some of the airframe maker’s most promising new technologies now sits at Boeing Field in Seattle, where crews prepare to install experimental systems that could appear in service as early as 2017 on the 737 MAX.
Just off Boeing’s narrowbody assembly line in Renton, Washington, the 737 “ecoDemonstrator” will carry no fewer than five separate developments, including an adaptive wing trailing edge meant to morph into an optimum shape during takeoff, climb, cruise and decent. The device works with an actuator that can deflect the last 4 percent of the airfoil up or down, thereby cutting fuel burn by making the wing more aerodynamically efficient and reducing takeoff noise by improving the airplane’s climb performance.
“The key for us is finding out a way to create an actuation system that is very light and efficient because these are very small devices,” ecoDemonstrator program manager David Akiyama explained to AIN. “There’s lots of different ways you can actuate it, so there are some systems that would actuate depending on the temperature, but you can also use electromechanical actuators or hydraulic actuators.”
Using standard aluminum alloy, engineers will modify a spare trailing edge to use in the demonstrator and bolt it onto the wing box. Once complete with testing, Boeing will simply remove the test part and replace it with the 737-800’s original trailing edge for delivery to the airplane’s eventual operator, American Airlines, explained Akiyama.
The airfoil technology–partially funded by a $25 million matching cost contract as part of the U.S. Federal Aviation Administration’s continuous lower energy emissions noise (CLEEN) program–won’t likely make its way onto a the MAX, changes to which Boeing wants to keep to a minimum. A more likely application, he said, would involve a new program or major derivative such as the 777X.
Active Engine Vibration Reduction
Another candidate for a MAX application centers on a technology under development to reduce engine vibration. The system, called active engine vibration reduction, senses imbalances caused by rotating turbomachinery in the engine and applies a counterforce–using a principle similar to that found in noise-canceling headsets–to cancel vibration that would otherwise make its way into the cabin and produce noise. “That’s a technology that you can retrofit to existing airplanes or apply to a brand-new airplane,” said Akiyama.
In the ecoDemonstrator’s cockpit, a system called flight trajectory optimization incorporates a broadband satellite antenna, a so-called an onboard networking system–or data backbone–and a system similar to a wireless network router to enable broadband communication both within the airplane and between the airplane and the ground.
The bandwidth such a system would carry could allow for transmission of real-time weather information to a wireless device such as an iPad in the cockpit, allowing pilots to immediately re-route around thunderstorms or turbulence, for example.
Variable Area Fan Nozzle
Another engine-related advance slated for testing on the ecoDemonstrator involves a fan nozzle that can open and close to allow for as much as a 10-percent variation in exhaust area. “Just like the adaptable trailing edges morphs the wing to optimize for all flight conditions, the variable area fan nozzle optimizes itself for takeoff, for landing as well as for cruise,” said Akiyama. “Most of the designs that are fixed geometry are a compromise. When you’re able to move geometry you can actually optimize it for each of those conditions.”
By opening the nozzle area during takeoff, for example, the fan won’t have to spin as fast to generate the same amount of thrust. The resulting decrease in jet velocity reduces noise and increases fuel efficiency.
Also slated for testing on the ecoDemonstrator, a regenerative fuel cell developed in partnership with Japan’s IHI likely wouldn’t appear in a large-scale application until after the turn of the decade. The technology involves the conversion of hydrogen into electricity that, on an airplane, could power systems independent of engine-driven generators, allowing for smaller, lighter power generation systems.
“This is taking technology that is much lower in maturity,” said Akiyama. “So we’re going to learn some very basic lessons on hydrogen handling, on coupling a fuel cell to the power systems of an airplane. But in terms of the actual hardware and technology being ready for application, we’re still many years away.”
Schedules call for the ecoDemonstrator to remain at Boeing Field for some 45 days, then travel to Glasgow, Montana, on or about August 18 for 30 days of intensive flight testing, flying as many hours as needed to complete the project.
Next year, Boeing plans to test ceramic matrix composite acoustic engine nozzles on a widebody airplane, most likely a 787 Dreamliner. Each year thereafter it plans to deploy a different platform to test still more advanced systems.