Since the beginning of 2020, 45 scientists from 20 DLR institutes have been working together in the EXACT project (Exploration of Electric Aircraft Concepts and Technologies) to develop new technology components for an eco-efficient commercial aircraft.
The overarching goal is to bring the necessary technologies for such an aircraft with at least 70 seats and a range of 2,000 kilometres to operational readiness by 2040. In a first step, different hybrid-electric drive concepts and possible aircraft configurations will be investigated. However, interactions with the airport infrastructure will also be considered, as will the impact of new types of drive systems on the atmosphere and thus on the climate.
With the help of data from the entire life cycle of an aircraft, from design and production to operation and subsequent disposal, the researchers are sifting through data from which they can derive knowledge for aircraft design. The specified objectives are that the aircraft’s emissions must not have a negative impact on the climate and that it must be operated economically. The design process is viewed holistically and geared to these goals. The planning of production, operation and maintenance are incorporated into the design from the very beginning. In the past, aircraft have been developed primarily on the basis of cost considerations and their impact on the climate has been analysed only afterwards. “We are turning this process around for the first time and are thus choosing a revolutionary approach to our work,” explains project leader Johannes Hartmann from the DLR Institute of Aerospace Systems Architectures.
Aircraft with an improved climate balance require fundamentally new propulsion technologies. The project team is therefore investigating which propulsion concepts for short-haul aircraft would result in significantly reduced emissions and less noise during operation and are compatible with the interests of industry. Batteries, fuel cells or hydrogen-powered aircraft offer the potential to reconcile these requirements.
The DLR Institute of Technical Thermodynamics has been analysing and evaluating the performance classes of fuel cells for aviation for several years. For example, fuel cells are characterised in the laboratory under this aspect and examined in the four-seater HY4 passenger aircraft. The knowledge gained in the EXACT project is now to be used with the aid of simulation models and pilot applications to evaluate and make the interaction of hybrid energy concepts applicable in larger performance classes.
New types of aircraft will influence the entire current aviation system and vice versa. In the EXACT project, DLR researcher Kai Wicke is looking at the operational and ecological integration of the new aircraft configurations: “Whether a new type of aircraft is powered by hydrogen, fuel cells or batteries – we take a holistic view of the effects this would have on the entire ecological and aviation system, i.e. on airports, airlines, air traffic control and the atmosphere”.
His team develops models for climate impact, noise, and product and energy life cycles. In doing so, environmental impacts as well as investment, operating and maintenance costs are examined. If an aircraft were to be refuelled with hydrogen, special refuelling systems would be required. Batteries would have to be charged, stored and recycled. The requirements of the existing infrastructure for the operation of a new aircraft must be clarified.
In four years’ time, a first holistic concept for environmentally compatible air traffic is to be developed. Aircraft engineers, atmospheric researchers and electrical engineers from 20 different DLR institutes are working together to establish valid models and develop solutions.
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