Boeing packages improved airframe, systems and flight-deck for combined flight-test effort
From the outside, 's EcoDemonstrator looks like any other , but beneath the skin this is a flying testbed for near-, mid- and long-term technologies the manufacturer hopes will dramatically improve efficiency and safety while reducing noise and fuel burn.
The EcoDemonstrator also represents a new way of testing for Boeing and is more than just a one-off exercise in packaging new ideas for a short flight-test program. Though the 737-800 will be refurbished for delivery in November to American, from which it is on loan, the aircraft is the first of a series of demonstrators that will help Boeing prove and fast-track advanced technologies into the product lineup.
As such, the EcoDemonstrator plan is a significant departure from past practices in which Boeing has flight-tested discrete, new commercial technologies on a platform-specific basis. Even the long-retired “Dash 80” 707 prototype, for example, which became a general workhorse for everything from high-flotation landing gear to aft-mounted engines, was never used for the range of simultaneous flight-deck, systems and aerodynamics tests like those packaged on the EcoDemonstrator.
The EcoDemonstrator concept provides a new tool for the company's product-development organization as it seeks to narrow down options for updates of current projects as well as future programs. Boeing says the initiative also forms an adjunct to continuing flight-tests of product-specific advances, such as the recently evaluated fuel-saving hybrid-laminar-flow-control system tested on afor application in the forthcoming 787-9 stretch.
The idea for the EcoDemonstrator series grew out of low-noise concept flights in the 2000s, culminating in the Quiet Technology Demonstrator (QTD) 2 in 2005. As a result of the QTD, engine fan-duct and primary nozzle chevrons that were tested on a-115B-powered are now seen everyday at airports around the world. Fan and core chevrons have migrated to the -2Bs on current production , while fan-duct chevrons also appear as standard on both GE and -powered 787s. Fan noise on the GE90-115B was reduced by increasing the sound-absorbing area of the inlet and was lip-tested in the QTD2, and the same technology helped avoid 200 lb. of sidewall sound insulation on the 787, not to mention the 600 lb. of sound-suppression weight saved by the chevrons.
Sensing the value of grouping together advanced-study concepts that by themselves may not have justified a dedicated flight-test effort, Boeing also flew a technology-demonstrator 737 effort in the mid-2000s that tested a range of flight-deck and connectivity developments. Pushed by Boeing's environmental performance senior technical executive and former QTD manager, Belur Shivashankara, plans for a follow-on program to the QTD2, meanwhile, morphed into an Environmental Technology Demonstrator before turning into the current test series.
“We have a plan to roll out EcoDemonstrators on a yearly basis,” says Jeanne Yu, environmental performance director for. The next demonstrator will be one of Boeing's original 787 development aircraft and is due to be modified in late 2013, while the company is reviewing options for demonstrators beyond that.
Among other technologies yet to be announced, the 787 will be testing a ceramic matrix composite (CMC) nozzle in one of its engines. The unit weighs less than current metallic nozzles and could last longer while enduring higher operating temperatures. The nozzle will be integrated with embedded acoustic treatment, which will be fitted to a.
Made by Alliant Techsystems' affiliate COI Ceramics and Albany Engineered Composites, it will also be the largest single piece of CMC in the world, says EcoDemonstrator program manager David Akiyama. Early 787 development aircraft ZA004 is currently the most likely platform, he notes. Although this was originally tested with the alternate GEnx-1B engine, Akiyama says, “that's the nice thing about the 787; it's designed for easy engine change.”
For now, the focus is on analyzing the results from this year's EcoDemonstrator, which is wrapping up flight tests with a final series of evaluations of devices to reduce engine vibration and a regenerative fuel cell. The fuel-cell work, conducted in association with IHI of Japan, is expected to lay the foundation for initial applications in ground power units, where weight is less critical but will lead to eventual use in aircraft for auxiliary power.
Regenerative fuel cells work much like rechargeable batteries and could power some electrical systems independently of engine-driven generators, says Akiyama. This would reduce the load of the aircraft's onboard electrical supply, allowing for smaller, lighter generation systems which, in turn, could reduce overall weight, fuel burn and emissions.
The active engine-vibration-reduction system tested dampers developed by Hutchinson Aerospace. Placed on the struts connecting the-7B engine to the airframe, the devices are designed to actively cancel out a vibration in the 737 cabin, which now can only be avoided by running at higher power during descent. Enabling the engine to run at lower-idle thrust settings during this phase of flight is expected to produce additional fuel savings.
Another technology demonstrated in the program was the use of radio-frequency identification devices (RFID) for faster checking of emergency equipment, such as passenger oxygen masks and life jackets. Mandatory manual checks of such equipment currently take operators 5 hr. to perform per aircraft, and the demonstration hoped to show this could be done in as little as 90 sec. using an RFID reader that scans them electronically.
Flight tests began in late August with evaluation of a series of aerodynamic and propulsion-system technologies at Boeing's remote test site here. The aircraft, already modified with a flight-test interior, was fitted with initial elements of the EcoDemonstrator package. This included a modified wing trailing edge which was funded by the's Cleen (continuous lower-energy, emissions and noise) environmental research program.
Boeing competed for the Cleen work that the agency is funding with $125 million over the next five years. The company attributes to its win much of the impetus behind the launch of the EcoDemonstrator.
The project grew from there, says John Coussens, principal investigator for the EcoDemonstrator program. “It was a small project at first, but it kept expanding to include more and more opportunities,” he says. “This is all about technology advancement through flight-testing.” Coussens was tasked with helping to define technology for flight tests as well as working with Akiyama to negotiate the contract with American Airlines. “The FAA wanted a U.S. airline and the 737 was an appropriate choice. The 737-800 was also the best fit because we needed the extra aft cargo area capacity to fit the fuel cell,” he notes.
The suite of technologies “evolved because everyone kept rallying around it,” says Akiyama. Testing of iPads and new applications in the flight deck was a typical add-on, he notes. “We were never looking at it to begin with, as we were looking at [electronic flight bags]. Tests of an iPad-hosted flight-trajectory-optimization app started out as real-time data to the flight-deck crew, but expanded,” he says. “Once we had an onboard network server [to transmit wirelessly to the iPads in the flight deck], the people with creative minds started to think of new applications—such as putting in security cameras to check what's happening in the cabin or behind the flight-deck door.”
While software and display-based experimentation is bounded largely by the imagination, testing of aerodynamic improvements is held firmly in check by the laws of physics. The chief focus for these were several configurations of adaptive trailing edges (ATE) aimed at improving aerodynamic efficiency by cutting drag and redistributing pressure loads.
Modifications included the addition of a fixed wedge on the trailing edges of the inboard and outboard flaps. “The real significance of what we're trying to do is introduce a secondary control surface that allows you to change the performance of the wing, and do it for every flight regime from takeoff and climb to cruise,” says ATE principal investigator Tad Calkins.
The fixed shape simulated a mini split flap. “We were interested in the low-speed conditions and the tests gave us aerodynamic, noise and loads data,” he says. A set of 40 shapes were made for the tests using stereolithography before being taped and glued onto the trailing edge. Bands of sensors were mounted fore and aft at different positions of the trailing edge along the span to assess the impact of the shapes.
“The whole idea is to develop the first real steps toward a morphing wing,” says Calkins. The outboard fixed trailing edge between the aileron and winglet was also modified to test both a mini plain flap and a mini split flap. Aerodynamic, loads and noise testing was performed on both versions of the ATE, the mini plain flap being converted relatively simply into a split flap by fixing a plate over the upper surface. The modified section, which occupied only 3% of the chord at the end of the wing, was 68 in. long and could be actuated to a range of positions from 60 deg. down to 30 deg. up.
“We used the same actuation technology for the mini split flap and mini plain flap, and on the right wing we built in flush-mounted pressure ports around the mini plain flap as well as pressure belts over the region for the wedges on the inboard and outboard flaps,” says Calkins. “We're giving more flexibility to the wing designer, and we've just added a new design element to the wing. We changed the position of the outboard section in flight and actually showed you can move to multiple positions and test aerodynamic, loads and noise conditions while we flew.”
Tests were also conducted on a variable area fan nozzle (VAFN), developed for the aft end of the 737-800's CFM56-7B engine with the assistance of. The VAFN is designed to adjust the exit area of the fan duct which, in current commercial high-bypass engines, is a fixed nozzle. The concept has been adopted for the Pratt & Whitney and PW1500G for the and , respectively. It is designed to improve fan efficiency during takeoff, climb and descent, and is expected to provide noise benefits. As the aircraft climbs to cruise altitude, the VAFN closes to produce an optimum exit area more suitable for the higher-altitude regime and acts “like a constant speed prop,” says Boeing New Airplane Product Development chief pilot Mike Carriker.
For Boeing's flight tests, the VFAN was fixed in the open geometry position and tested primarily for its effect on noise. “We're taking a look at community noise impact with the variable area in the deployed position,” says Akiyama. “Preliminary indications are that it is performing as expected. But we have to complete our analysis, and at the same time, we're testing our analysis and prediction tools.”
As the VAFN could affect the stability of a fan stage not designed from the outset to work with a variable area nozzle, the decision was made to restrict the operating altitude of the testbed to 10,000 ft. with the unit in place. The VAFN was therefore installed here after the 737 had crossed the mountains between Seattle and the test area in Montana.
The existing nacelle was modified by cutting “a slice around 4.5 inches in from the trailing edge,” says Dean Parham, Boeing nacelle designer and VAFN patent holder. “We put in a second slider that moves the second sleeve aft to open up the flow by 10% for takeoff and low-power settings.” The VAFN also angles out slightly as it translates aft. However, “the flow doesn't separate,” says Parham, adding that the design incorporates seals to prevent leakage. “That was the hardest part. Leakage is bad for efficiency, and when it is stowed, it is watertight. We put it in a box and pressure-tested it to 4 psi.”
For flight tests, VAFN is actuated hydromechanically, though for a fully functioning system that can be actuated in flight, Boeing is looking at “electrical, hydraulic and even mechanical” options, says Parham. The device could be automatically stowed when the leading edges are cleaned up, or it could be controlled by the electronic engine control. Either way, Boeing says the system's operation will be transparent to the crew.
Preflight test development included performance and noise-testing with CFM at GE's Peebles ground-test facility in Ohio. Initial acoustic results validated predictions, according to Parham, who says, “we weren't at all worried about noise.”
Boeing also took advantage of the EcoDemonstrator to test new methods of connectivity with the ground as well as wireless-enabled flight-deck display and cabin information applications. The overall suite has the potential to bring current production and older aircraft up to 787 standards in terms of connectivity and could provide the basis for improving pilot situational awareness and strategic route-planning on all models.
As with the other components under test, the scope of the systems experiments snowballed, says Tim Rahmes, flight sciences engineering and flight trajectory optimization principal investigator. “We wanted to do something to kick-start the uplink of weather data, and we realized it would support a variety of capabilities. It became a sort of 'build it and they will come' thing. None of this is guaranteed to be a future offering yet, but it is looking pretty promising.”
The idea of uplinking live weather imagery to aircraft over the wide expanses of ocean where there is no such conventional coverage (such as Nexrad over the continental U.S.), became more urgent following the 2009 weather-relatedFlight 447 accident in the South Atlantic. “We need something that's global, and that's why we chose a global system which is lightweight,” says Rahmes. The configuration tested on the 737 included a Swift intermediate-gain broadband antenna from CMC Electronics, a satcom data unit and a Boeing-built Onboard Network System (ONS)—a network file server that connects via a wireless network to other aircraft systems.
“It's a suite of capabilities,” Rahmes says. “That's the enabling aspect of what we're doing with this framework. The network file server can also host a lot of such things as aircraft health management, flight data-recorder streaming, downlinking of weather observations and quick-access recorder data.”
The systems architect on Boeing's electronic flight bag (EFB) project, Matt Jarka, says the system goes beyond the EFB, which “historically have been embedded into the aircraft. Flight crews have transitioned to electronic operations, but in most cases these have been very [centered on] the aircraft. What we're doing with the mobile device initiative (and the iPad is the most requested by our customers) allows us to extend EFB off the aircraft, and pilots can take it with them to airline operations and back to their hotels.”
Although the initiative appears to be at odds with Boeing's long-running EFB development, the manufacturer says it is better to be leading the mobile device initiative than letting another company take away its market. The demonstrator is also helping to explore “how best to integrate and display that information in the flight deck,” says Jarka.
“We are allowing the iPad to communicate directly with the aircraft, and that's something we haven't done before. It connects to the ground servers in flight so we can upload live weather, and we are testing it to download mock defect reports,” Jarka says. “This is taking it to the next level, because it's getting to the point where this is real-time data, and airplane health management is a big part of that. The 737 in particular doesn't have this capability, but with this system, we just brought the 737 10 years into the future. In effect, with ONS we take a 737 and bring its technology base up to 777 or 787 levels.”
Android and Windows 8 mobile devices will also be studied, with the Android system due for testing in 2013. “We have a close relationship with Windows and will look into it this year,” Jarka says.