Gulfstream Aerospace has completed a series of test flights aimed at determining whether the use of clean sustainable aviation fuel (SAF) can reduce particulate emissions associated with the formation of aircraft contrails.

As part of the program, the Gulfstream G800 business jet flew at altitudes of up to 15,200 meters, using only 100% SAF without the addition of conventional aviation kerosene. According to the company, this was the first flight for both the G800 itself and its Rolls-Royce Pearl 700 engine conducted entirely on such fuel.

For the experiment, a specially modified Gulfstream G700 flew alongside the G800, turning it into a full-fledged airborne laboratory, Naked Science reports. The two aircraft flew in close formation, allowing researchers to directly measure in flight the concentration of emitted particles and atmospheric parameters at altitudes higher than the typical cruising level of most passenger airliners, but characteristic of business aviation.

The tests were conducted jointly with the ASCENT research center, which is part of the U.S. Federal Aviation Administration (FAA). NASA, the German Aerospace Center (DLR), the Missouri University of Science and Technology, Aerodyne Research, Rolls-Royce, Montana Renewables, and World Fuel Services also took part in the project.

The scientists compared the characteristics of three types of fuel:

conventional Jet A aviation kerosene;

low-sulfur Jet A;

fully sustainable HEFA SAF fuel (Hydroprocessed Esters and Fatty Acids).

Unlike conventional aviation fuel, the HEFA SAF used in the tests contains neither sulfur nor aromatic hydrocarbons.

Preliminary results showed a noticeable reduction in the amount of particulate matter, which plays a key role in the formation of contrails, when the G800 operated exclusively on this type of fuel.