Piston aircraft engines are also deployed in military aviation. Thielert supplies its certified CENTURION® engine also for use in unmanned aircraft, otherwise known as unmanned aerial vehicles (UAV), which are increasingly used in the military sector for missions involving high-investment and cost-intensive products.

The US Department of Defense and the NATO are endeavouring to operate with a single type of fuel from 2008. This principle was made public under the name of "Single fuel for the battlefield" (DoD Directive 4140.25) and is aimed at improving the logistics, availability, range and cost-efficiency of the armed forces. Against this backdrop, the decision has fallen in favour of diesel fuel or "heavy fuel". This is due to the fact that even today in the NATO states the engines of most military applications run with various diesel raffinates such as jet fuel, JP-8 and JP-5. In connection with this, the diesel engines for UAV are also known as heavy fuel engines (HFE).

The American company General Atomics Aeronautical Systems, Inc. has already installed the CENTURION® engine in its UAVs. The maiden flight of the Predator Warrior model took place in October 2004. The HFE Warrior UAV is the long-distance HFE version of the mission-tested Predator UAV with a conventional petrol engine and is designed to be used by the U.S. armed forces as a communication station in long-term observations and in supply missions. The Warrior was selected by the U.S. Army for the Extended Range Multi-Purpose (ER/MP) UAV Program lasting over several years.