DLRmagazine 175 (June 2024)

A future without contrails?

With its nose close to the exhaust jet, the DLR research aircraft Falcon was on the move during the campaign pictured on the cover of DLRmagazine 175. DLR uses such research flights to investigate the influence of sustainable aviation fuels on the climate impact of air traffic. Almost half of this impact consists of so-called non-CO2 effects, which also include contrails. The majority of these have a warming effect on the climate. DLR scientists are also investigating how clever flight route planning can reduce this effect. Other topics in this issue include a DLR start-up that is developing sustainable fuels for spaceflight, an autonomous rail bus and much more.


Did you know that nearly half of the climate impact of aviation consists of non-carbon-dioxide effects? These include contrails – the only effect that can be observed in the sky with the naked eye. Most contrails have a warming effect on the climate. Their formation could be reduced by clever flight route planning – leading to an immediate effect on the carbon footprint of aviation.

However, more flexible route planning has a number of consequences. Air traffic controllers must be able to quickly react to changing conditions. New, improved assistance systems, which are being developed at DLR and allow flight route adjustments to be made in real time, can provide support here.

The systems need to be fed with data to enable reliable modelling, for example on weather and climate developments. DLR researchers are working on new modelling tools. DLR measurement technology has also been installed in commercial aircraft for 30 years now and provides valuable data on the composition of the atmosphere.

But to significantly reduce the climate impact of air traffic, we need to do more. This is why DLR experts are also focussing on alternatives to fossil fuels. They are researching Sustainable Aviation Fuels (SAFs), that could reduce both carbon dioxide emissions and the formation of contrails. Find out why and how the amount of SAF already produced today could be beneficial and what the market ramp-up of these fuels could look like in the future in our magazine article.

Sustainable fuels are also becoming increasingly important in spaceflight. The fuels developed by the DLR spin-off InSpacePropulsion Technologies are less harmful and easier to handle than the current standard. InSpacePropulsion Technologies is just one of many examples of how DLR is bringing basic research to the market via technology transfer.

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On course for climate compatibility

As the latest addition to DLR's research fleet soars above the Bavarian town of Bad Tölz, only the aircraft's livery hints at its future mission. By the end of 2025, the Dornier 328 turboprop passenger aircraft will have been converted into an UpLift flight test platform for environmentally friendly technologies. The aim of the UpLift project is to support the development of all technologies that will help to make aviation more sustainable. In this context, the aircraft will be made available as an open test platform. Among other things, the turbines are being adapted to be able to operate with fully formulated synthetic aviation fuels (SAFs). For the first time, researchers will be able to analyse the air chemistry and contrail formation of a turboprop aircraft that runs 100 percent on aromatic-free SAFs in real-life operations. Aromatics – cyclic hydrocarbons – are an essential component of conventional aircraft fuels; for one thing, they cause the polymer seals of tanks to swell, preventing fuel leaks. However, they are largely responsible for the formation of soot during fuel combustion in engines. Aromatic-free SAFs, by contrast, reduce soot formation and thus also the formation of contrails. UpLift will be presented for the first time at the ILA International Air Show in Berlin from 5 to 9 June 2024. The main target group for the UpLift flight test vehicle, registered as D-CUPL, is the German aviation industry – especially small and medium-sized enterprises that do not have their own research aircraft. DLR is cooperating with Deutsche Aircraft GmbH on the current conversion and expansion of D-CUPL into a flying test bed. D-CUPL will be stationed at DLR's Flight Experiments facility in Braunschweig.

Download the DLRmagazine 175


Editorial team DLRmagazine

German Aerospace Center (DLR)
Corporate Communications
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