OBJECTIVE: Develop and demonstrate lightweight, high effectiveness, low cost recuperators for small turbine engines to power small manned and unmanned aerial systems for increased reliability and operational capability. DESCRIPTION: Tactical requirements for Army manned and unmanned aerial systems are exceeding current capabilities for performance (payload, range, time on station), reliability, maintainability, and supportability. Mission requirements such as increased power, extended endurance, low altitude maneuverability in urban environments without detection, and high reliability are becoming paramount. These requirements are currently not fully realized with conventional rotary, internal combustion, or turbine-based propulsion. Electrical power requirement for advanced payloads is also increasing, which adds weight to the air vehicle. Turbine based propulsion systems offer improved power to weight ratio over typical internal combustion engines, however, do not compete well in fuel efficiency in small size engines due to increased clearances and losses. The addition of recuperation can improve small turbine fuel consumption across the operational spectrum, such that it is competitive with internal combustion engines. This would allow Army manned and unmanned aerial systems to take advantage of the turbine engine"s inherent reliability and durability, while reducing the weight advantage somewhat. Therefore, for a successful recuperated small turbine engine (30-700 horsepower) to be developed for application to Army manned and unmanned aerial systems, it will be critical for the recuperator to be lightweight, have high effectiveness for good fuel consumption characteristics, use low-cost manufacturing techniques, and be durable/reliable so that overall engine performance, cost, and reliability/durability is achieved. The objective of this topic is to develop lightweight, high effectiveness, low cost, and durable/reliable recuperators for small turbine engines, which offer potential for increased engine power to weight ratio and reliability, in order to meet current and anticipate future needs of Army manned and unmanned aerial systems. Current conventional engines are sized to provide enough power and speed for takeoff capability, often leading to a propulsion system which operates inefficiently at other operating conditions. An advanced recuperated propulsion system would need to be able to meet different operational requirements of a small/mid-sized manned and unmanned aircraft, which include full power takeoff capability, high part-power cruise fuel efficiency for improved endurance, and quiet operation capability. Additional capabilities required for both Army manned and unmanned aerial systems include the ability of the engine to operate off of heavy-fuel (JP-8, diesel) and ability to provide power to electrical payloads. PHASE I: During Phase I effort, key components of the proposed recuperated engine concepts should be developed and validated to substantiate the ability to provide a lightweight, high effectiveness, low cost, and durable/reliable recuperator that can be integrated into a current or future turboprop/turboshaft engine system. A lightweight recuperator design will increase the weight of the engine system by no more than 80%. The target specific fuel consumption (sfc) reduction for the recuperated engine system will be 35% less than that of the baseline engine system. PHASE II: Phase II will fully develop, fabricate, and demonstrate the full recuperated turboprop/turboshaft engine system in a ground test environment. PHASE III: Phase III options should include endurance testing and integration of the enhanced propulsion system into the airframe and demonstrate the performance of the system with flight testing in an Army manned or unmanned aerial system mission environment.