A Saab Gripen fighter has for the first time undergone a series of test flights with 100% biofuel. This demonstrates that the aircraft can be flown entirely with an alternative fuel and gives valuable knowledge for future possible use of alternative fuel.
The tested fuel—Catalytic Hydrothermal Conversion Jet fuel (CHCJ-5)—was made from rapeseed oil. CHC fuels—which are also being evaluated by the US Navy for inclusion in the JP-5 spec (earlier post)—use a catalytic hydrothermolysis process that chemically converts renewable feedstocks such as triglycerides, plant oils, and fatty acids into a mixture of paraffins, cycloparaffins, aromatics, olefins, and organic acids. The resulting mixture is then hydroprocessed and fractionated to produce a kerosene (or diesel) product having a distillation profile comparable to traditional petroleum derived fuels.
The end product is a fuel that is able to meet the jet (or diesel) chemical and physical MIL-SPEC requirements without blending with conventional petroleum fuels.
This was the first time that a single-engine fighter flew with 100% biofuel. The flights were conducted with a Gripen D (dualseat) at Saab’s facilities in Linköping and went entirely as planned. (The Gripen D is a two-seat version of the single-seat Gripen, used
The test team noted no differences between the biofuel and the ordinary jet fuel, which means that biofuel can be used as a fully satisfactory alternative to ordinary jet fuel in Gripen. Flying with biofuel in operational service with Gripen requires, however, further certification of the fuel and access to fuel in the amounts that correspond to operational needs.—Göran Bengtsson, Director of Research and Technology, Future Business, Aeronautics
The Swedish Defence Materiel Administration (FMV) is behind the project; FMV, Saab and GKN Aerospace, which produces the engine (RM12) for the Gripen C/D, participated in the project. The RM12 is a modular, fuel efficient, low bypass ratio afterburning turbofan in the 80 KN (18,000lb) thrust class. It is based on the General Electric F-404-400 which has completed several million flight hours in operations worldwide, with several enhancements including increased thrust and bird strike resistance.
Through a bilateral agreement between Sweden and the United States, the US Navy and US Air Force have contributed with valuable knowledge and experience regarding certification of biofuel. System testing, ground testing and flight testing have been conducted at Saab in Linköping together with GKN Aerospace.
The Gripen fighter is in service with a number of air forces: Swedish, Czech, Hungarian, South African and Thai. The UK Empire Test Pilots’ School (ETPS) is operating Gripen as its advanced fast jet platform for test pilots worldwide. Also, Brazil has signed a contract for the development and production of 36 Gripen NG fighter aircraft.
McDaniel, A., Dickerson, T., Luning-Prak, D., Hamilton, L. et al. (2016) “A Technical Evaluation of New Renewable Jet and Diesel Fuels Operated in Neat Form in Multiple Diesel Engines,” SAE Technical Paper 2016-01-0829 doi: 10.4271/2016-01-0829