The drive for environmental sustainability comes in many forms and from all sectors of the aviation industry, and Boeing’s completion in early September of its latest ecoDemonstrator flight trials centering on noise, airspace routing efficiency, and cabin disinfection certainly applies to business jets as much as airliners.
Performed over about a week of flying twice a day from a former U.S. Air Force base in Glasgow, Montana, and during individual positioning flights between Seattle's Boeing Field and the company’s Dreamliner assembly plant in Charleston, South Carolina, the tests evaluated the effectiveness of noise-mitigating fairings attached to the 787-10’s Safran landing gear. Further noise testing involved the use of 200 small microphones attached to the left side of the aircraft’s fuselage and 1,000 more listening devices on the ground in Montana.
Addressing both environmental efficiency and safety, the testing also demonstrated a system meant to more accurately guide flights around hazards such as storms, allowing pilots to better plan their routes and more quickly arrive at their destinations. Boeing flew the set of tests with up to a 50-50 blend of jet-A and sustainable alternative fuel (SAF) derived from agricultural waste from California.
EcoDemonstrator program manager Doug Christensen explained that the routing optimization trials incorporated a system called Four-dimensional Trajectory Optimization and the Terminal Area Management System under development at NASA. The system uses digital signals via satellites that ground personnel send to the flight deck and provide immediate information that now gets communicated via radio transmission or Acars.
“It basically allows the team on the ground to identify hazards and send up new routings to the airplane,” explained Christensen. “And then the pilot has the ability to either accept or modify. So it's really looking at how do we get the pilots on the airplane the most information that they can to fly the airplane efficiently and without a lot of radio frequency tuning or additional activities by the pilot. So it creates an environment for the pilots where they can just see the weather front, they can look at the suggested re-routing and accept it all with just a couple touches of a button.”
Boeing performed a final demonstration of the technology on its return flight from Seattle to Charleston, from where the 787-10 flew to Abu Dhabi for delivery to Etihad.
Another communications technology tested on the ecoDemonstrator involved a NASA-developed system called a Tailored Arrival Manager (TAM), which uses existing airplane and ground-based digital systems to enable more precise approach and arrivals. That capability minimizes the need for holding patterns for landing slots, enables more accurate time of arrival, and reduces noise and emissions, according to ecoDemonstrator chief engineer Rae Lutters.
The two main components of the TAM experiment involve integrating digital communications equipment on board the aircraft and testing the actual architecture that provides automated advisories to the pilots, a NASA spokesman told AIN. TAM advisories allow for increasingly autonomous air-ground trajectory management for arrivals using existing avionics. The system uses AutoResolver, which among other functions provides conflict-free, continuous-descent trajectories for aircraft merging at an arrival-metering fix.
Under the TAM testing process, NASA receives data, including planned arrival trajectory, from the aircraft via Boeing’s ground facility. Engineers then model a standard arrival delay due to high demand at the destination and propose a new trajectory that meets that time. The new trajectory then gets sent to the FAA Data Comm lab via NASA’s North Texas Facility (NXT), and the FAA sends the trajectory as a new clearance via Controller-Pilot Data Link Communications (CPDLC) over a test channel.
Another element of environmental sustainability Boeing addressed during this phase of its ecoDemonstrator program centered on noise generated by the airframe and landing gear. The 200 small microphones attached to the airframe comprised a sensor array that sent signals to the aircraft's data system. Those, along with 1,000 microphones on the ground, measured the noise footprint of the airplane in various configurations during simulated takeoffs and landings, explained Lutters.
In fact, Boeing in part picked Glasgow as the location for the test flights for its lack of city and traffic noise, allowing for more precise sound measurements from the aircraft, said Christensen. “We're working with NASA on this to build a giant database and data set that we can use to develop tools that will help us design airplanes in the future to be more quiet,” he explained. “It's really a data-gathering exercise so that we understand where the noise is coming from and how we can then design those noise sources out of our next generation of airplanes.”
One resonance source often overlooked—the airplane’s landing gear—can account for a third of the sound generated during landing, said Lutters. The idea behind the fairings attached to the 787-10’s Safran right-side landing gear centered on addressing airflow disruption that obstructions from various components cause after deployment for landing. “When the landing gear comes out, there’s struts, there’s tubes, there’s brakes…all of those things are potential noise sources,” said Christensen. “So the fairings we’re looking at are [ways to] try to smooth that flow out around some of those major components.”
Separately, engineers tested a new hand-held wand to kill germs on surfaces within the cabin such as Covid-19. Using 222-nanometer ultraviolet light, the wand disinfected the 787 flight deck in less than 15 minutes. The device could take the place of alcohol or other disinfectants that might damage electronic equipment, explained Lutters. The team also tested an antimicrobial surface coating on the flight deck during 16 flights.
The Etihad 787-10 was the seventh test platform used since the start of the ecoDemonstrator program in 2012. Over the eight years of the program, Boeing has managed to apply several of the tested items to production airplanes. One of the earliest studies, in 2012, resulted in the Advanced Technology winglet that now appears on the 737 Max. Along with the inward, upward, and slightly forward lift components of the upper airfoil, the addition of a lower airfoil improves efficiency by generating a vertical lift component that is vectored away from the fuselage and also slightly forward.
On the 777X, Boeing has incorporated touchscreen displays first tested in 2014 and in 2016 signed a contract with Rockwell Collins (now Collins Aerospace) to supply the devices on all five flight deck displays.
More recently, in 2018, Boeing tested a new Lidar unit on a FedEx 777F to detect clear air turbulence, a leading cause of injury on commercial airplanes, explained Christensen.