An Airbus initiative to enable a long-haul aircraft to harness the wake energy of a preceding jet has received a boost from Germany’s DLR aerospace institute, which is developing software tools to enable such formation flights.
Airbus launched its fello’fly test programme in November 2019 claiming it could bring fuel savings – and emissions cuts – of between 5-10% by enabling a trailing aircraft to benefit from the smooth updraft of air created by the wake of another large jet flying around 1.6nm (3km) in front.
In-house tests were conducted last summer using a pair of A350s and have continued since, the airframer says; trials involving A350 operators French Bee and SAS are scheduled to take place later in 2021.
It has also been working with multiple air navigation service providers – DNSA in France, NATS in the UK, plus Eurocontrol – to refine the concept, with Canada’s NAVCANADA added earlier this year.
Airbus hopes to make sufficient progress to allow “a controlled” introduction of the concept by mid-decade in oceanic airspace.
However, the DLR, working with universities in Aachen and Hamburg, has also been studying the topic under the German government-funded FORMIC project.
The DLR calculates that the proposed wake-harnessing flights could cut fuel consumption by 5% and lower the overall climate impact by 25%, through a reduction in the formation of contrails.
Because the contrails – which contribute to global warming through retention of heat in the atmosphere – produced by a pair of aircraft in formation share the water content in the atmosphere, there is less scope for contrails to form than with two aircraft flying separately, says the DLR.
In addition, it has developed a software toolkit, called MultiFly, to identify jets that can be paired in formation – initially just aircraft of the same type.
The toolkit calculates where two formation partners meet, which route they will fly together and where they will eventually part ways. Finding aircraft that can fly together for as long as possible despite departing from different airports is key to operational success, says the DLR.
“By considering global air traffic, the use of formation flight could help us achieve a large positive effect for climate protection, and it would require relatively little effort,” says DLR project manager Tobias Marks.