13/03/2019
In the bustling world of air travel, the journey doesn't just begin and end in the sky. A significant portion of an aircraft's operational time, and thus its fuel consumption and emissions, occurs on the ground during taxiing. Traditional taxiing involves using the aircraft's main engines, which are powerful but inefficient for slow ground movement, leading to unnecessary fuel burn and noise pollution. Enter electric taxiing systems, a game-changing innovation designed to revolutionise airport operations. Among the pioneers in this field, Safran Landing Systems (SLS) is at the forefront, meticulously refining its 'eTaxi' system, poised to redefine efficiency and sustainability for future narrowbody aircraft.
- What is Safran's eTaxi System?
- The Evolution: From EGTS to eTaxi's Refinement
- Engineering the Future: How eTaxi Works
- Unlocking Efficiency: The Core Benefits
- Current Development Status and Future Vision
- Comparative Analysis: EGTS vs. eTaxi
- Frequently Asked Questions (FAQs)
- Q: What exactly is electric taxiing?
- Q: How does Safran's eTaxi differ from traditional taxiing?
- Q: What are the main benefits of using eTaxi?
- Q: Will eTaxi be on current aircraft models?
- Q: How much fuel can be saved with eTaxi?
- Q: What's the environmental impact?
- Q: When can we expect to see eTaxi in commercial use?
What is Safran's eTaxi System?
Safran's eTaxi system is an advanced electric taxiing solution designed to allow aircraft to move independently on the ground without relying on their main engines or external tugs. Instead, it harnesses electricity, generated by the aircraft's Auxiliary Power Unit (APU), to drive electric motors strategically attached to the main landing gear wheels. This innovative approach offers a multitude of benefits, from significant reductions in fuel consumption to a quieter, cleaner airport environment. Unlike previous iterations or concepts, the eTaxi unit is specifically designed for 'line-fit' installation on future aircraft, meaning it's intended to be integrated into the aircraft's design from day one rather than being retrofitted.
This design philosophy ensures optimal integration, weight management, and performance. Kyle Schmidt, senior vice-president of research, technology, innovation and eco-design at SLS, highlights that the latest version of the eTaxi system is 'really responding to what airframe customers are telling us they want'. Furthermore, the system is conceived to be both 'removable and optional', offering flexibility to airline operators who can choose whether or not to include it on their aircraft based on their specific operational needs and economic models.
The Evolution: From EGTS to eTaxi's Refinement
Safran's journey into electric taxiing is not new. Over a decade ago, the company collaborated with Honeywell to develop a prototype system known as the Electric Green Taxiing System (EGTS). This initial endeavour, while groundbreaking, ultimately saw the project abandoned in 2016. The primary challenge with EGTS was its design intent: it was being integrated onto in-production aircraft, which presented limited potential to optimise the weight and fit of the design. Retrofitting such a complex system onto existing airframes proved to be an engineering and economic hurdle.
Learning from this experience, Safran Landing Systems adopted a fresh approach with eTaxi. The current system, now in its 'third or fourth generation', proposes a similar fundamental architecture to EGTS – with electric taxi actuators installed on the main gear wheels – but with a crucial difference: it's being developed for *future* aircraft. Schmidt explains, 'By designing eTaxi for a future airplane we can make the interface cleaner,' while 'trying to minimise added weight.' This forward-thinking design strategy allows for seamless integration and significant weight reduction efforts. Indeed, progress made since EGTS was dropped has seen the system's weight cut by around 100kg at the aircraft level, a testament to Safran's continuous commitment to innovation and efficiency.
Engineering the Future: How eTaxi Works
The technical ingenuity behind eTaxi lies in its robust and efficient actuators. Each actuator, mounted on the main gear wheels, is a self-contained module packed with sophisticated components. It contains a high-torque electric motor, crucial for providing the necessary power to move a heavy aircraft from a standstill. This motor is coupled with a gear-reduction drive, which multiplies the torque, enabling precise and powerful control over the wheel's rotation. A clutch mechanism is incorporated for both engagement and positive disengagement of the system from the wheel, ensuring seamless transitions between electric taxiing and traditional engine-powered movement, or when the system is not in use.
To maintain optimal performance and prevent overheating, cooling fans are integrated within the module. All these components are housed within associated hardware, designed to operate the system as a 'convenient and easily mountable/detachable module'. The torque delivery capability of each actuator is impressive, ranging from 6,000 to 12,000Nm, depending on the specific aircraft application and desired performance targets. This ensures that the system can handle the varying demands of different narrowbody aircraft models effectively.
Unlocking Efficiency: The Core Benefits
The advantages of Safran's eTaxi system are multifaceted, promising substantial improvements in both operational efficiency and environmental impact:
Significant Fuel Savings
The most compelling benefit of eTaxi is its potential to cut 'block fuel burn by up to 4%'. Block fuel burn refers to the total fuel consumed from engine start to engine shut-down, encompassing taxiing, take-off, flight, and landing. By eliminating the need to use the powerful, fuel-guzzling main engines for ground movement, eTaxi dramatically reduces fuel consumption during the taxi phase. This percentage, though seemingly small, translates into enormous savings for airlines over thousands of flights annually, contributing directly to their bottom line and making air travel more economical.
Reduced Environmental Impact
Beyond fuel savings, eTaxi offers profound environmental benefits. The reduction in reliance on main engines during taxiing directly leads to a significant decrease in harmful emissions at the airport. This includes carbon dioxide (CO2), nitrous oxides (NOx), and particulates. Lower emissions mean cleaner air around airports, which are often located near populated areas, improving local air quality and reducing the carbon footprint of aviation. Furthermore, electric taxiing is inherently quieter than engine-powered taxiing, contributing to reduced noise pollution in airport vicinities, a key concern for local communities.
Enhanced Operational Efficiency
While not explicitly stated to replace tugs entirely, a self-taxiing aircraft reduces the reliance on external ground support equipment for pushback and manoeuvring on the tarmac. This can lead to faster turnaround times, improved gate utilisation, and greater operational independence for aircraft. It streamlines ground operations, potentially reducing delays and improving overall airport flow, making the entire process more efficient and predictable.
Optimised Weight vs. Performance
One of the critical challenges in aviation technology is managing added weight. While the eTaxi system does add mass compared to a standard wheel, Safran Landing Systems is confident that the fuel efficiency it brings will more than compensate for this extra mass. Schmidt states, 'We are working out how we get the system lighter, reduce the parts count and make sure it buys its way on to the airplane a bit better.' The 100kg weight reduction from previous iterations is a significant step, demonstrating that the benefits in fuel savings and reduced emissions are expected to outweigh the mass penalty, making it a viable and attractive proposition for airlines.
Current Development Status and Future Vision
Safran Landing Systems is actively pushing the eTaxi system through its development phases. Currently, the technology readiness level (TRL) for the system as a whole stands at TRL 3 or 4, indicating that the basic technological components have been validated experimentally, and key elements are being refined. Certain specific elements of the system have even reached TRL5, meaning they have been validated in a relevant environment.
An SLS team is 'actively working' on the system, focusing on continuous improvements. Their goals include further reducing the system's weight and simplifying its parts count, ensuring it becomes an even more compelling proposition for airframers and operators. Safran has never wavered in its belief in the eTaxi concept. 'We have never stopped internally working on eTaxi,' says Schmidt. 'We are firm believers that this brings advantages for operators and airframers.'
The primary target market for eTaxi is the next generation of narrowbody aircraft. While neither Airbus nor Boeing currently has a formal demand for such a system, SLS is proactively maturing the technology. Their objective is to ensure that eTaxi can be readily offered to either airframer as they begin to contemplate replacements for their highly successful A320neo and 737 Max single-aisle aircraft in the 2030s. This foresight positions Safran as a key enabler for the future aircraft landscape, aligning with the industry's broader push towards more sustainable and efficient operations.
The development of eTaxi is also part of a wider suite of research and technology (R&T) activities at SLS. These include the electrification of other landing gear components and the exploration of lightweight materials, all of which are designed to find their way onto next-generation aircraft, contributing to a holistic approach to aviation sustainability.
Comparative Analysis: EGTS vs. eTaxi
To truly appreciate the advancements in Safran's current eTaxi system, it's helpful to look back at its predecessor, the Electric Green Taxiing System (EGTS), and understand how the lessons learned have shaped the current design:
| Feature | Electric Green Taxiing System (EGTS - Old Approach) | eTaxi System (Current/Future Approach) |
|---|---|---|
| Design Intent | Retrofit for existing, in-production aircraft models. | Line-fit for future narrowbody aircraft models. |
| Integration | Limited potential for optimal integration; challenges with fitting onto existing airframes. | Designed for deep integration from day one; allows for a cleaner interface and optimised fit. |
| Weight Management | Heavier due to the challenges of retrofitting; less scope for weight optimisation. | Significant weight reduction achieved (approx. 100kg at aircraft level) compared to EGTS. Ongoing efforts to further reduce mass. |
| Project Status | Project with Honeywell abandoned in 2016. | Actively being refined; current Technology Readiness Level (TRL) 3/4, with some elements at TRL5. |
| Flexibility | Less adaptable to varying aircraft designs due to retrofit nature. | Designed to be 'removable and optional', offering flexibility to airline customers. |
Frequently Asked Questions (FAQs)
Q: What exactly is electric taxiing?
A: Electric taxiing is a technology that allows an aircraft to move on the ground, between the gate and the runway, using electric motors integrated into its landing gear, rather than relying on its main engines. This system is typically powered by the aircraft's Auxiliary Power Unit (APU).
Q: How does Safran's eTaxi differ from traditional taxiing?
A: Traditionally, aircraft use their powerful main jet engines for taxiing, which are designed for flight and are inefficient at low speeds, consuming a lot of fuel and generating noise and emissions. Safran's eTaxi uses dedicated electric motors on the landing gear, offering a more fuel-efficient, quieter, and environmentally friendly way to move around the airport.
Q: What are the main benefits of using eTaxi?
A: The primary benefits include significant fuel savings (up to 4% block fuel burn), reduced emissions (CO2, NOx, particulates) at airports, quieter ground operations, and potentially improved operational efficiency by reducing reliance on external ground support equipment.
Q: Will eTaxi be on current aircraft models?
A: No, Safran's eTaxi system is specifically designed for 'line-fit' integration into *future* narrowbody aircraft, such as the replacements for the Airbus A320neo and Boeing 737 Max models expected in the 2030s. It is not intended for retrofit on current aircraft.
Q: How much fuel can be saved with eTaxi?
A: Safran estimates that the eTaxi system can cut block fuel burn by up to 4%, leading to substantial cost savings for airlines over the lifetime of an aircraft.
Q: What's the environmental impact?
A: By reducing the use of main engines during ground operations, eTaxi significantly lowers emissions of carbon dioxide, nitrous oxides, and particulates at airports, contributing to cleaner air and a reduced carbon footprint for the aviation industry.
Q: When can we expect to see eTaxi in commercial use?
A: Safran is actively developing and refining the eTaxi system, with an eye towards its integration into new aircraft programmes emerging in the 2030s, aligning with the timelines for next-generation narrowbody aircraft.
If you want to read more articles similar to Safran's eTaxi: The Future of Greener Aviation, you can visit the Taxis category.