Search Results

Small remotely piloted aircraft (10-25 kg) powered by internal combustion engines typically operate on motor gasoline, which has an anti-knock index (AKI) of >80. To comply with the single-battlefield-fuel initiative in DoD Directive 4140.25, interest has been increasing in converting the 1-10 kW power plants in the aforementioned size class to run on lower AKI fuels such as diesel and JP-8, which have AKIs of ~20. It has been speculated that the higher losses (short-circuiting, incomplete combustion, heat transfer) that cause these engines to have lower efficiencies than their conventional-scale counterparts may also relax the fuel-AKI requirements of the engines. To investigate that idea, the fuel-AKI requirement of a 3W-55i engine was mapped and compared to that of the engine on the manufacturer-recommended 98 octane number (ON) fuel.

As the maintenance and disposal costs of aircraft batteries have risen, it has become critical to increase battery lifetime and to reduce maintenance cycles. This has led to the development of charging techniques designed to increase battery life while continuing to satisfy battery performance requirements. However, the cost of battery chargers accounts for 60% to 80% of the battery/charger system cost. AFRL/PRPB has initiated an in-house project to evaluate F-16 batteries using the existing F-16 charger. The objective is to determine which batteries can pass all F-16 performance and lifetime requirements using this charger. Several batteries were procured from several sources and two F-16 chargers are on loan to us from Sacramento/ALC. Depending on the outcome of this phase the project may be extended to include other aircraft and other chemistries such as Nickel-Metal Hydride and Lithium-Ion. Results to date and future plans will be discussed in this paper.