The Southwest Research Institute (SwRI) of San Antonio, TX, says it has successfully tested a new aircraft piston engine that operates on heavy fuels, such as diesel or jet fuel.

The demonstration test of the heavy-fuel engine (HFE) was conducted in an unmanned aerial vehicle, or UAV, similar to those used in military reconnaissance missions. Whereas traditional UAVs burn gasoline and therefore require availability of a separate fuel supply, use of HFEs in such applications would help to unify the military's fuel supply and storage needs.

Although the HFE demonstrated by SwRI uses JP-8 jet fuel, it's a single-cylinder, spark-ignited, water-cooled piston engine producing 25 hp. It also produces no visible exhaust, indicating complete combustion, says SwRI.

SwRI says that possible future applications of the HFE include motorcycles and stationary power units. This would further push the military towards reliance on only a single fuel.