Delivering more environmentally sustainable technology to customers and partners is clearly now a matter of "how and when" rather than "if" for major aerospace and defense groups like Raytheon Technologies (Stand 1351). Briefing reporters ahead of this week’s Dubai Airshow as the United Nations COP26 climate change conference was underway in Scotland, LeAnn Ridgeway, the newly appointed chief sustainability officer with the company's Collins Aerospace unit, said that pressure from political and business leaders, as well as environmentalists, is making it more imperative for the industry to deliver a credible path to reducing and eliminating carbon and other harmful elements.
“We are seeing an acceleration [in expectations for progress] and on a global stage there are a lot more conversations around this,” she said. “We are getting more requests for proposals with sustainability goals, and we’re looking to do whatever we can to accelerate progress.”
Aircraft engines are probably the most visible part of aviation’s environmental problem, and Raytheon’s Pratt & Whitney and Collins Aerospace businesses are both active in implementing a multi-stage approach to decarbonizing propulsion. But government customers for the group’s Missiles and Defense unit also now expect greener military technology, prompting company initiatives such as reducing the power requirements for its vast sea-based X-band radar systems. With improved liquid cooling and air conditioning, such installations now need 4.4 million kW/hours of power, which Jennifer Hubbard, executive director for strategic sensor systems, said equates to heating 4,360 homes for a month.
For Michael Winter, senior fellow with Pratt & Whitney, his team's call to action addresses aviation's journey toward accounting for between 18 and 20 percent of human-generated carbon dioxide emissions by 2050, compared with around 2.5 percent now. In the first instance, Pratt & Whitney still sees further progress in improving fuel efficiency from more improvements in gas turbine technology, such as the Geared Turbofan it introduced in 2016. Those engines have now surpassed 11 million flight hours.
To improve propulsive efficiency, Winter said there is scope to increase bypass ratio from current levels of 12 or 13 to as much as 15 or 18, as demonstrated in test programs with, respectively, NASA (under its Sustainable Flight National Partnership) and the FAA (through its Continuous Lower Energy, Emissions, and Noise initiative). He said new turbofans with such bypass ratios will be available for new airframes now in the early stages of development.
In order to boost thermal efficiency, Pratt & Whitney is working to have engines operating at higher temperatures and with smaller cores using new materials such as ceramic matrix composites (CMC). The company has invested over $100 million in a CMC pilot plant in California and a further $650 million to develop the capability at a facility in North Carolina to make higher-temperature castings to produce the required units at scale.
Winter said the industry needs advances in turbofan architecture and performance to deliver environmental progress that other measures such as increasing the use of sustainable aviation fuel (SAF) or introducing battery-electric or hydrogen-electric propulsion systems cannot fulfill. But those future technologies have entered development, and Raytheon has begun making investments in them as well.
“For hybrid-electric [propulsion] we see a sweet spot in the market somewhere around one megawatt with all the associated components that Collins Aerospace is developing for propulsion systems for domains of aviation including urban air mobility, regional air mobility, regional turboprops to single-aisle [airliners] and beyond ” Winter explained.
In July, Pratt & Whitney announced a joint C$163 million investment program with the governments of Canada and Quebec for De Havilland of Canada and Collins to develop a hybrid-electric demonstrator based on the Dash 8-100 regional aircraft. Over a 250 nm sector, the project aims to demonstrate a 30 percent reduction in fuel burn and CO2 emissions compared with existing twin-turboprop aircraft. Collins is providing a one-megawatt electric motor and controller, while Pratt & Whitney Canada focuses on the batteries.
Colleagues from Pratt & Whitney and Collins also are collaborating in systems engineering work to apply hybrid-electric propulsion to larger single-aisle airliners, which require around 18 MW of power for takeoff. They are looking at putting a 1 MW starter generator on the core of the engine and another unit on the low-spool of the turbofan to achieve a 5 percent gain in energy efficiency.
Meanwhile, Pratt & Whitney is pushing for all of its engines to run on 100 percent SAF. As regulators address the 47 different parameters they must consider to ascertain whether any engine can use any type of pure SAF, the company has developed a test sequence to facilitate approval. The FAA and EASA have shown differing viewpoints on 100 percent SAF approval, making it hard to predict exactly how and on what terms they'll clear the unblended fuel ffor widespread use.
In her new role coordinating Collins’s concerted press to make aviation greener, Ridgeway said the company is increasing investments in materials and systems that contribute to greater energy efficiency and reduced emissions to contribute to the broad industry goal of net-zero carbon by 2050. Last year the company established a cross-functional task force with its customers, while also drawing on expertise and ideas from employees across all of its business units through what it calls its “Ideas Launchpad.”
To bring home to colleagues the incremental significance of their individual and collective contributions to improving aircraft and their systems, Collins has used a “benefit estimator” to show the correlation between weight and power. Roughly speaking, every one-kilogram reduction in aircraft weight results in a one-kilogram cut in emissions for every 10 flight hours flown by every aircraft in every airline fleet, the tool shows.
To improve the operational efficiency of aircraft, Collins is looking to harness the benefits of the so-called connected ecosystem in which real-time data is used for predictive functions that can, for example, optimize flight routes to burn less fuel. It will also deploy artificial intelligence and routing tools that leverage airspace information, atmosphere data, and aircraft state and performance data for dynamic route optimization. The group’s precision navigation and satellite communications systems are being deployed in work with air navigation service providers to deliver air traffic management systems that support operators in reducing fuel burn.