A Low Profile, Horizontal Waterjet for Combatant Craft Signature Reduction

"Propulsion systems aboard current SOCOM Combatant Craft utilize propulsor systems that produce large wake forms, such as rooster tail. Large wake forms exaggerate the true visible and radar cross section of the Combatant Craft and thus increase probabilityfor detection by littoral sensor and radar systems. Common propulsor designs, which originated from the commercial and recreational industries, are not ideal for military operations that require a high degree of concealment. High profile waterjet wakeforms can potentially compromise mission objectives. Orbital Research proposes a novel nozzle design that can be readily adapted to existing SOCOM watercraft propulsors to significantly reduce visible and radar signatures. This unique nozzle concept willreduce wake side profile by nearly 50% without losses in thrust or watercraft performance. In the Phase I, Orbital Research will conduct actual water tests on the proposed nozzle designs. In addition, Computational Fluid Dynamics (CFD) simulations will beperfomed to optimize internal geometry for proper mixing and flow behavior. Thrust, waterjet impingement, and signature reduction will be quantifed from both experimental and CFD data. Several combatant craft, such as the MK V Special Operations Craft,the Rigid Inflatable Boats, and the Riverine, are currently in need of advanced propulsor designs, create a potential market for this specialized propulsor system. Other applications may