Germany’s DLR aerospace research centre has for the first time measured the emissions from a turboprop aircraft with both engines running on 100% synthetic fuel while on the ground.
Carried out in mid-September at Oberpfaffenhofen airport near Munich, the trials used a Dornier 328 test aircraft, dubbed UpLift, previously supplied by type certificate holder Deutsche Aircraft.
In-flight emission measurements will follow later in October, using the UpLift and a Dassault Aviation Falcon 20E chase aircraft operated by the DLR.
“While the use of alternative fuels in jet aircraft has already been investigated in several studies, systematic data on the emission behaviour of turboprop engines is still lacking,” says Nina Gaiser, head of the ground measurement campaign at the DLR’s Institute of Combustion Technology in Stuttgart.
“For this reason, studies on how pollutant emissions change when using aromatic and sulphur-free synthetic fuel compared to standard kerosene are of particular scientific interest.”
A specially designed measurement probe was used for the testing, capable of collecting exhaust samples and sending them back to a nearby mobile laboratory for analysis.
Samples were collected at different power levels – simulating everything from low-thrust taxiing to high-thrust take-offs – and from varying distances behind the engines to “provide important insights into the dispersion and ageing of aerosols in the exhaust plume”.
Previous tests had analysed the emissions from the turboprop operating in a “dual-mode configuration” – with one engine burning standard Jet A-1 and the other a power-to-liquid (PtL) proxy fuel.
Preliminary results from these trials show a “a significant reduction in particulate emissions when PtL proxy is used”, says the DLR.
For the UpLift trials, the fuel used was a 100% aromatic-free Fischer-Tropsch Synthetic Paraffinic Kerosene provided by Sasol.
Deutsche Aircraft is developing a stretched and modernised version of the Do 328 – the D328eco – which will be capable of running on 100% sustainable aviation fuel.
