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Global-Warming-Optimized Aircraft Design

Periodic Reporting for period 2 - GLOWOPT (Global-Warming-Optimized Aircraft Design)

Reporting period: 2021-03-01 to 2022-12-31

The aviation sector must undergo a revolution as commercial air travel is growing at an impressive pace, and the impact of emissions on climate change at high altitude are deemed very relevant. Currently, aircraft are being operated at multiple routes at a combination of speed and altitude that maximizes revenue. This implies that most transport aircraft fly at altitudes where non-CO2 effects (from NOx emissions, contrail formation etc.) are high, resulting in a negative climate impact. These non-CO2 effects and their climate impact largely depends on the atmospheric state. The targets set by ACARE of 75% CO2 and 90% NOx emission reduction, respectively by 2050 relative to a baseline aircraft from the year 2000 are pushing the aviation industry to rethink how aircraft are designed and operated.

In aircraft design studies, fuel burn, maximum take-off mass or direct operating cost are often used as cost functions. However, more than 50% of the climate impact from aviation is stemming from non-CO2 effects. Hence it is essential to include these non-CO2 effects to develop climate optimized aircraft design. The high-level objective of GLOWOPT is to develop novel Climate Functions for Aircraft Design (CFAD) with respect to minimizing climate impact and for their application to the multidisciplinary design optimization of next generation aircraft. The CFAD developed will address the aircraft design process and include the effects of non-CO2 emissions with implicit information about the route network. GLOWOPT established close interaction between scientific partners, aviation stakeholders, and the general public to guarantee broad dissemination of the project results

GLOWOPT directly addresses the specific issue of minimization of global warming by performing an aircraft design optimization based on CFAD that leads to a design solution with substantially lower climate impact compared to a reference design while considering the operating regime of the relevant market segment. GLOWOPT defines a set of top-level requirements for the next generation climate optimized aircraft design. Also, a higher-fidelity assessment of the climate optimized aircraft design developed within GLOWOPT is carried out to validate the CFAD. Finally, GLOWOPT addresses the performance of the climate optimized aircraft in terms of operating cost, noise, and local air quality.
Extensive research of previously performed projects dealing with the climate impact of aircraft design and aircraft operations was conducted to summarize the current knowledge on the relationships between aircraft design parameters and their impact on climate was done in WP 1. An analysis of the worldwide aircraft fleet and route structure in the future was done by adapting and applying an existing air traffic forecast model. The market segment operated with aircraft types with seats over 250 were selected. The route network corresponding to this market is made available for developing Climate Functions for Aircraft Design (CFAD) as a part of WP 2. A suitable climate metric (Average Temperature Response over 100 years, ATR100) was selected. A long-range wide body, similar to the existing A350-900, was selected as reference aircraft.

The CFAD are developed as a response surface model with 3-D (latitude, longitude and altitude) emissions distribution as an input in WP 3. The input emission inventories are calculated for varying cruise altitudes and climb angles to determine the influence of the aircraft design performance. These CFAD were then integrated into an existing MDO framework to design climate optimized aircraft designs in WP 4. The climate optimized aircraft design reduced 63% in ATR100 compared to the reference aircraft. This is facilitated by operating at a cruise altitude of 6km and Mach number of 0.63. Low altitude cruise reduces the contrails' impact by 81% and reduced engine overall pressure ratio reduces the NOx impact by 72%. A higher fidelity assessment of the climate optimized aircraft conducted in WP 5 shows that the CFAD are able to estimate the contribution of each climate agent with under 3% relative error. However, the direct operating cost and flight time of the climate optimized aircraft increased by 17% and 23%, respectively, when operated on the entire network compared to the reference aircraft.

Dissemination and communication activities were carried out with continuous exchange with stakeholders. The communication channels were set up, i.e. the web ( and linked-in profile ( with satisfying KPIs. Project members participated in several conferences and workshops.
By the development of aircraft design-related CFAD, GLOWOPT will support the design of new aircraft with significantly reduced climate impact. The amount of CO2 and NOx emissions will be reduced by using these CFAD in the MDO process, but more importantly, the operating regime of the aircraft is changed such that the location/altitude of the emissions will be shifted to less climate-sensitive regions. The increasing importance of non-CO2 effects of aviation can be responsibly considered in the development of next-generation aircraft. GLOWOPT will make sure that the CFAD are generated not solely on an academic basis but tailored to the characteristics of the future air traffic demand in terms of markets and design requirements. GLOWOPT is aiming to contribute to the competitiveness of the European Union and ultimately secure and improve mobility. GLOWOPT gives the possibility to address the full suite of climate impacts beyond CO2 emissions in the CS2 Technology Evaluator (TE). This enables assessments within the TE: First, a climate impact assessment of the emission inventories developed within the TE and second, a climate impact assessment of the technologies.

Both members of the GLOWOPT consortium are universities that do research and teach in aerospace and air transportation systems, respectively. By nature, they utilize and exploit the knowledge and experience gained during the course of this project in order to
- further improve the state-of-the-art on environmentally-optimized aircraft design advance
- lectures on aircraft design and operations and thus educate MSc students, PhDs and Postdocs and provide data from the project for their research work
Top view comparison of the reference and climate optimized aircraft
Development Methodology of Climate Function for Aircraft Design (CFAD) response surface
Comparison of Climate Impact contributors between reference and climate optimized aircraft