Self Energized Packaged Oil Systems: Simple, Low Cost, Lightweight, and High Efficiency Non-recirculating Lubrication systems for Small Limited-life e

The development of small limited-life engines for use in Unmanned Aerial Vehicles (UAV) in expendable and attritable weapon systems will be critical to maintaining air superiority as the landscape of the modern warfighter changes. The National Defense Strategy (NDS) identifies a central challenge to US prosperity and security as the reemergence of long-term, strategic competition posed by Russia and China. The Navy is responding by developing a range of UAV, Unmanned Undersea Vehicles (UUV), and Unmanned Surface Vessels (USV) to enable a shift in focus towards smaller platforms that are more dispersed in their operation[1]. The increase in the geographical scale of the battlefield will drive the need for a larger quantity of expendable and attritable solutions, in addition to the existing larger, higher cost, lower quantity platforms. An important piece to successfully executing this strategy will be the development of low cost, easy to manufacture weapon systems. There is a unique opportunity to simplify existing designs that can be realized as a consequence of designing for limited life or single use applications. Traditional approaches to engineering development leverage the so-called legacy design approach. An approach which seeks to minimize disruption to the function of the system by minimizing change. By leveraging already working designs it is possible to reduce development cost and time and consequently, many of the mechanical systems currently implemented in small attritable engines are scaled down versions of those implemented in larger engines. This approach has significant limitations; it obscures a region of design space that is more desirable for these special engines - i.e. alternative concepts that may have winning attributes in the small engine space will not be considered if solutions are simply scaled versions of larger designs. Additionally, implementing designs which leverage legacy-based systems can often overlook system level improvements. As pointed out by the author’s of this topic, traditional flow through and recirculating oil systems can account for up to 30% of overall propulsion system weight, yet these designs haven’t changed in almost 100 years. A fundamental design philosophy utilized in Zulu Pod’s technology is to look at bearing lubrication and thermal management from a new perspective, specifically focused on conditions relevant to small attritable/expendable engines. In this design space wear and durability constraints are less severe and the primary design objective is to prevent catastrophic failure modes. It is then possible to innovate by separating the functions of lubrication and cooling by pushing the design in regimes where lubrication is optimized, and cooling needs are minimized. Preliminary results suggest that mechanical systems which do not need to be operated for tens of thousands of low cycle fatigue conditions will require only modest amounts of lubrication.