Researchers at NASA’s Aviation Research Centers Improve Flight Efficiency in Dynamic Environments

Air travel is a complex balance between meticulous planning and dynamic adaptations. Long before an aircraft touches the runway, pilots file detailed flight plans outlining their intended routes. However, once in the air, these plans often undergo modifications due to various factors such as turbulence, weather changes, and unforeseen circumstances. Adapting to these challenges on the fly requires quick thinking from pilots, who must communicate any alterations to air traffic controllers promptly.

Traditionally, these adjustments happened abruptly and with limited lead time. As aviation embraced digital connectivity, aircraft began leveraging additional data, leading to the development of technologies aimed at optimizing flight paths. One such innovation is NASA’s Traffic-Aware Strategic Aircrew Requests (TASAR), a software designed to assist pilots and ground operations teams in finding optimal routes during transit.

NASA’s interest in enhancing aircraft efficiency is deeply rooted in its history. Notable contributions, like the development of winglets, have significantly impacted aviation. Winglets are upturned vertical flanges at the ends of airplane wings that reduce turbulence at the wingtip, resulting in substantial fuel savings. The evolution of these two technologies began at NASA and continue as two of the most recent NASA spinoffs, sliding almost seamlessly into people’s everyday lives like many of NASA’s innovations. TASAR and winglets contribute to a more sustainable, eco-friendly, and passenger-friendly future for aviation.

TASAR: Navigating the Skies with Precision

Planning for Efficiency

Experienced airline pilots have a keen understanding the challenges and intricacies of air travel planning. They meticulously plan their routes, factoring in variables such as weather conditions, air traffic, and fuel efficiency. These plans serve as a roadmap for air traffic controllers, providing a structured approach to managing the airspace.

However, once in-flight, these plans can quickly become obsolete. Turbulence, changing weather patterns, and other unforeseen events necessitate real-time adjustments. These adjustments must be communicated to air traffic controllers. However, pilots do not always get much advance warning of conditions that force them to change their flight paths. They face the challenge of having to choose the best/ new route within minutes at most. This is where TASAR comes into play.

The Genesis of TASAR

David Wing, the principal researcher of air traffic management at NASA’s Langley Research Center in Hampton, Virginia, is at the forefront of developing advanced autonomy systems for aircraft. His expertise lies in enabling operators to manage flight paths efficiently, especially in crowded skies. Recognizing that the technology used for safe routing could also optimize routes for in-flight flights, Wing conceptualized TASAR.

TASAR, short for Traffic-Aware Strategic Aircrew Requests, is a piece of software that empowers pilots and ground operations teams to identify and adopt better routes during transit. The driving force behind TASAR is a genetic algorithm, a machine learning system that pits hundreds of potential route changes against each other to find the optimal solution. The software takes a map of the area, draws hundreds of lines radiating from the airplane representing potential routes, and systematically narrows down the options. It avoids routes that intersect with no-fly zones, dangerous weather systems, or other aircraft, ultimately determining the most efficient path for the airplane.

From Algorithm to Aircraft

While the algorithms behind TASAR had been tested and refined over the years in NASA’s autonomy research, connecting this system to a real aircraft presented new challenges. The software’s success was demonstrated in NASA test flights, but for wider adoption, commercial planes needed to access substantial amounts of data.

iJET, a company initially focused on keeping planes connected to the latest ground information, provided a solution. By building better antennas and an integrated computer system for airplanes to receive and stay connected to ground-based information sources, iJET laid the groundwork for TASAR’s integration. Recognizing TASAR’s potential, the company acquired the technology and, after being renamed APiJET, became the first to license TASAR from NASA.

TASAR in Action: Digitizing Flight Optimization

Digital Winglets: Bridging the Gap

APiJET, now equipped with TASAR, sought an ideal application for this innovative technology. As APiJET aimed to keep planes connected to the latest information available on the ground, TASAR emerged as the perfect fit. Under the leadership of Rob Green, CEO of APiJET, the company integrated TASAR into its new computer system for airplanes. This integration marked the birth of Digital Winglets, a transformative technology named after NASA’s winglet invention that had been contributing to fuel savings for decades.

Digital Winglets operate on electronic flight bags, which are FAA-approved computer devices commonly integrated into flight operations, often in the form of Apple iPads. This approach ensures ease of updating the application while maintaining compliance with aviation regulations. The program was tested with Alaska Airlines, resulting in a remarkable 2% reduction in fuel consumption, equivalent to approximately 28,000 pounds of fuel per hundred flights.

While a 2% reduction might seem modest, the impact on an industry scale is substantial. As Green emphasized, “Two percent may not sound like much, but little savings can really add up at airline scale.” Several more airlines have since tested Digital Winglets, with Frontier Airlines currently conducting field tests for potential deployment across its fleet.

Beyond Fuel Savings: Environmental Impact

The significance of TASAR and Digital Winglets extends beyond fuel savings. In an era where environmental concerns are paramount, reducing fuel consumption directly contributes to lower carbon emissions. Green highlighted the environmental benefits of the technology, stating, “If you burn less fuel, your emissions will go down as well.” APiJET’s winglets provide up to a 6% reduction in carbon dioxide emissions and an 8% reduction in nitrogen oxide, addressing environmental challenges associated with air travel.

In addition to environmental considerations, the benefits of winglets extend to operational improvements. Reduced drag allows aircraft to operate over a greater range, carry more payload, and climb with less drag during takeoff. These enhancements are particularly critical for flights departing from high-altitude, high-temperature airports. Furthermore, winglets contribute to quieter operations, reducing the noise footprint by 6.5%.

The Evolution of Winglets: Enhancing Aerodynamics for Efficiency

Aerodynamics: Lift, Drag, and the Role of Winglets

Aerodynamics, the study of the behavior of air as it interacts with solid objects, is a cornerstone of aviation. Two fundamental forces, lift, and drag, define an aircraft’s performance. Lift enables flight by creating a pressure difference between the upper and lower surfaces of the wings, while drag is the resistance encountered during forward motion.

One significant source of drag is induced drag, resulting from wingtip vortices. These vortices, created by the pressure difference at the wingtips, lead to a disruption in airflow and hinder aircraft performance. Induced drag, a drag force associated with lift production, impacts fuel mileage, range, and speed.

In 1897, British engineer Frederick W. Lanchester conceptualized wing end-plates to mitigate the effects of wingtip vortices. However, it wasn’t until the 1970s that NASA’s Richard Whitcomb conducted groundbreaking research on the aerodynamic benefits of winglets.

NASA’s Pioneering Research on Winglets

In response to the 1973 oil crisis, NASA initiated the Aircraft Energy Efficiency (ACEE) program to explore ways to conserve energy in aviation. Whitcomb, an aeronautical engineer at Langley Research Center, conducted extensive computer and wind tunnel tests to investigate the impact of a vertical wingtip device, which he called a “winglet.” His hypothesis was that a precisely designed winglet could weaken wingtip vortices, thereby reducing induced drag and improving the overall lift-drag ratio.

In 1976, Whitcomb published his findings, predicting that winglets could decrease induced drag by approximately 20% and enhance the lift-drag ratio by 6 to 9%. These findings sparked interest in the aviation community, leading to collaborative efforts between NASA, the U.S. Air Force, and The Boeing Company.

Flight Testing Winglets

The collaborative effort resulted in a winglet flight test program at NASA’s Dryden Flight Research Center in 1977. Boeing, under contract with NASA, manufactured a pair of 9-foot-high winglets for the KC-135 test aircraft provided by the U.S. Air Force. The tests validated Whitcomb’s predictions, demonstrating a 7% increase in the lift-drag ratio and a 20% reduction in induced drag.

The success of the Dryden test program marked a turning point, confirming the viability of winglets as a technology that could significantly improve aircraft efficiency. Winglets had no adverse impact on aircraft handling, and the positive results encouraged widespread adoption across the aviation industry.

Commercial Adoption and Further Developments

While winglets for smaller jet aircraft began to emerge in the late 1970s, large airliners adopted the technology later. In 1989, Boeing introduced winglet-enhanced 747-400 aircraft, and in 1990, the McDonnell Douglas MD-11 with winglets entered commercial service.

In 1999, the partnership between Aviation Partners Inc. and The Boeing Company led to the formation of Aviation Partners Boeing (APB). This collaboration aimed to equip Boeing Business Jets with a unique take on winglet technology—Blended Winglets.

Blended Winglets: Merging Form and Function

The Design Philosophy

Blended Winglets, the brainchild of Aviation Partners Boeing, represent a refined evolution of the original winglet concept. Unlike traditional winglets that have a more angular design, Blended Winglets seamlessly blend with the wing in a smooth, upturned curve. This design not only enhances aerodynamic efficiency but also addresses a critical issue known as interference drag.

Interference drag occurs when two lifting surfaces intersect, creating airflow separation. The gradual blend of Blended Winglets resolves this problem, allowing for smoother aerodynamics and optimal efficiency. According to Mike Stowell, APB’s Executive Vice President and Chief Technical Officer, this design choice is crucial: “There is an aerodynamic phenomenon called interference drag that occurs when two lifting surfaces intersect. It creates separation of the airflow, and this gradual blend is one way to take care of that problem.”

Broad Adoption and Environmental Impact

The success of Blended Winglets is evident in their widespread adoption across various Boeing aircraft models. Thousands of Boeing airplanes, operated by numerous American and international airlines, feature APB’s Blended Winglets. Airlines, including major carriers like Southwest Airlines and Ryanair, have embraced the technology to capitalize on the fuel economy it offers.

The fuel savings provided by Blended Winglets range between 4% and 6%, a significant improvement in an industry where fuel costs are a major operational expense. Stowell emphasizes the economic and environmental impact, stating, “Fuel is a huge direct operating cost for airlines. Environmental factors are also becoming significant. If you burn less fuel, your emissions will go down as well.”

Winglets’ Impact on Aviation

Quantifying the Savings

The impact of winglets on fuel savings is not only significant but also measurable. APB announced in 2010 that its Blended Winglet technology had saved 2 billion gallons of jet fuel worldwide. This achievement translated to a monetary savings of $4 billion and a reduction of almost 21.5 million tons in carbon dioxide emissions. The environmental benefits of reduced emissions are crucial in an era where sustainable aviation practices are increasingly prioritized.

Looking ahead, APB anticipates even greater fuel savings, with a projected total surpassing 5 billion gallons by 2014. As the only company currently manufacturing and retrofitting winglets for commercial airliners, APB plays a pivotal role in advancing winglet technology and its applications.

Advancements in Winglet Technology

The journey of winglets doesn’t end with Blended Winglets. APB continues to explore ways to advance winglet technology, with a particular focus on spiroid winglets. These looped winglet designs, developed and successfully tested in the 1990s, demonstrated a fuel consumption reduction of more than 10%. The continuous pursuit of innovation in winglet design reflects APB’s commitment to pushing the boundaries of aerodynamic efficiency.

While winglets require meticulous customization for each type of aircraft, their universal benefits make them an effective solution for enhancing the performance of various makes and models. Beyond commercial carriers, winglets find applications in smaller jets, general aviation aircraft, and even unmanned aerial vehicles, demonstrating the versatility and impact of NASA’s pioneering research.

The Intersection of TASAR and Winglets: A Holistic Approach to Efficiency

A Unified Vision

TASAR and winglets, seemingly distinct technologies, converge in their shared goal of enhancing the efficiency of air travel. TASAR optimizes in-flight routes, allowing aircraft to navigate dynamically through airspace while minimizing fuel consumption. On the other hand, winglets address aerodynamic challenges, specifically induced drag, leading to substantial fuel savings and environmental benefits.

A holistic approach to efficiency involves combining these technologies, creating a symbiotic relationship that maximizes the benefits of both TASAR and winglets. By leveraging TASAR’s real-time route optimization capabilities and the aerodynamic enhancements offered by winglets, the aviation industry can achieve unprecedented levels of efficiency and sustainability.

Collaborative Innovation

The collaborative spirit that marked the development of winglets at NASA’s Dryden Flight Research Center in the 1970s is echoed in the evolution of TASAR and Digital Winglets. As aviation partners like APiJET and NASA work hand in hand, innovations emerge that shape the future of air travel.

The integration of TASAR with Digital Winglets exemplifies the synergy between digital technologies and aerodynamic advancements. Pilots now have tools that not only optimize their routes dynamically but also contribute to environmental conservation by reducing fuel consumption and emissions.

Navigating the Future of Air Travel

The intersection of TASAR and winglets marks a pivotal moment in the evolution of air travel. As the aviation industry grapples with the challenges of sustainability, efficiency, and technological advancement, these innovations offer a glimpse into a future where aircraft operate seamlessly through optimized routes, minimizing their impact on the environment.

From the meticulous planning of flight paths to real-time route optimization, TASAR exemplifies the power of digital solutions in enhancing aviation efficiency. Similarly, winglets, born out of NASA’s commitment to energy conservation, continue to revolutionize aerodynamics, delivering tangible fuel savings and environmental benefits.

The combination of TASAR and winglets presents a unified vision for the future of air travel—a future where aircraft not only navigate the skies with precision but do so with less environmental impact. As the aviation industry embraces collaborative innovation, these technologies pave the way for a new era of sustainable and eco-friendly flying.