DON26BZ01-NV005 — Low-Cost Multi-Mission Dip Sonar for Mine Warfare and Antisubmarine Warfare (Inner/Middle Zone)
Award Maximum: $140,000 (Base) / $100,000 (Option) Period of Performance: 6 months (Base) + 6 months (Option) Phase Type: Phase I
OBJECTIVE: Develop initial designs for a reduced cost, next generation helicopter dip sonar system utilizing multi-frequency band capabilities for traditional and enhanced anti-submarine warfare (ASW) capabilities for both inner and middle zone coverage (broadening to wide area search) as well as introducing aviation (naval) mine countermeasure (AMCM) capabilities.
DESCRIPTION: The United States Navy has long utilized dipping sonar systems on aircraft for Air ASW. The most recent sonar systems continue to show dominance in the Air ASW role with the ability to cover larger and larger areas of ocean. Simultaneously, various configurations of acoustic, electro-optic and electromagnetic sensor systems have been used in AMCM operations, with the newest remaining fielded systems offering limited mission coverage. As the Navy looks to new maritime strike future vertical lift capabilities, there will be an increased effort to combine capabilities into fewer unique aircraft platforms. To facilitate the merger of missions into fewer aircraft, it will become crucial to also combine more mission capabilities into individual mission systems. The resultant design from this effort is expected to provide increased capabilities across more aircraft of a singular configuration with the combination of improved Air ASW capability and added AMCM capability into a singular mission system, which in turn also will reduce the expected training and logistics costs with fewer variants of equipment to cover. Additionally, with continued retirements of existing mine-countermeasures systems, the Fleet will have an urgent need for other air-based AMCM capabilities/coverage and may want to consider implementing capabilities on other naval helicopters using existing, modified, or new sensors of acoustic, electro-optic, magnetic, and radio-frequency types.
Traditionally, the Navy developed and fielded acoustic ASW and AMCM systems independently while the physics of the underwater acoustic environment is a shared problem with differing targets and typical frequency bands of interest as a result. Additionally, acoustic ASW systems (i.e., sonobuoys and helicopter dip sonars) are of compact size and can be utilized on a medium lift helicopter or smaller, while acoustic AMCM systems have typically targeted installation on heavy-lift helicopters. Incorporation of a secondary frequency band capability into a helicopter dip sonar transducer assembly would quickly bring AMCM capability to a typically large number of traditionally ASW helicopters and bring air-based AMCM capability to the Navy's air-capable ships, simultaneously with ASW capability. The multi-mission capability of such a sonar transducer assembly would also allow one aircraft, without reconfiguring, cover both ASW and AMCM mission sets for reduced maintenance and reducing the equipment needed to be stored while afloat in space-constrained ships.
The objective is to develop initial designs for a reduced cost, next generation helicopter dip sonar system utilizing multi-frequency band capabilities for traditional and enhanced anti-submarine warfare (ASW) capabilities for both inner and middle zone coverage (broadening to wide area search) as well as introducing aviation (naval) mine countermeasure (AMCM) capabilities.
The system would also be utilized either in its full capability configuration or at a reduced capability configuration as a retrofit into the multi-mission helicopter as a replacement for the existing dipping sonar system transducer, while at a decreased unit and sustainment cost (below Class A mishap thresholds if lost in flight, with a goal of below a Class C threshold).
Minimally funded Science and Technology efforts have previously been performed to assess USN dipping sonar capability to detect naval mines using the system, acoustic pulses/frequencies, and processing in its existing ASW configuration and have shown success in detecting nearly every naval mine based on post-flight data analysis. Enhancing that capability with a secondary frequency band and associated beam steering, as well as uniquely developed pulses and processing across both frequency bands, is expected to provide a significant AMCM capability while retaining both traditional ASW superiority and enhanced ASW detection and classification capabilities for certain scenarios.
In addition to introducing AMCM capabilities into a traditional ASW sensor system, no significant improvements in the traditional ASW sonar transducer assemblies available from industry have been introduced since the last dipping sonar system competitive source selection conducted in the late 1980s. Increasing costs of the existing USN sonar systems continue to drive concerns regarding the long term affordability of the existing fielded systems and any future variants thereof, and continue to pose a risk of generating an equipment cost loss equivalent to a Class A mishap record if the transducer is lost from the aircraft. As such, decreasing the recurring production costs of a future transducer assembly are of significant concern and ensuring improved supportability. Noting that sonobuoys are similar advanced acoustic sensor systems made in large quantities for production unit costs of less than $15k/each indicates that a highly capable sonar transducer design would be capable of being generated with a much more reasonable forecast production cost well below $500k/each.
Additionally, the ability for the new sonar transducer to be retrofit in place of existing USN fielded sonar transducers (form/fit/function compatible) used on the existing USN aircraft while utilizing existing sonar processing (~3-5 kHz frequency band) and bringing AMCM capability and new added ASW capabilities to the traditionally ASW-focused helicopters is of interest utilizing a higher frequency band in the same unit.
Lastly, it would be a significant advancement in helicopter-based ASW capabilities if a tertiary frequency band below 2 kHz was also added to expand mission capabilities to broach wide area search and explore advantages of convergence zone type capabilities, while retaining the inherent existing direct path detection coverage of the mid-frequency 3-5kHz band, for full spectrum coverage of the surrounding areas.
The new multi-frequency band sonar transducer would be desired to have at least the following characteristics: Primary transmit array would be omnidirectional for ASW in the horizontal plane; Primary acoustic transmit band for ASW: 3-5 kHz; Primary receive array would be capable of supporting 24 beams for primary ASW capabilities; Consider using Single Crystal transducer technology or other new technology to reduce the weight and improve bandwidth; Overall weight must be less than 180 lbs.; Primary electronics power and transmission signal power for the unit must be provided from an external transmitter/amplifier; Primary acoustic processing must occur offboard (not within unit); Secondary higher frequency band must be selected for AMCM mission optimization; Secondary transmit and receive array functionality could reuse the primary arrays, utilizing electronic or physical manipulation as needed/possible to optimize AMCM. Alternatively, integrating other transmit and/or receive arrays within the same assembly may be acceptable; The secondary array capabilities would consider abilities to steer beams both horizontally and vertically depending on both mine and submarine targets of interest; As allowable, a tertiary capability of covering lower frequencies for longer range area searches and overlap with current other low frequency system operational frequencies (below 2 kHz) is preferred; Mechanically extended and retracted arrays are acceptable; Will be capable of storage within an aircraft body for forward flight, ideally with an overall stowed diameter of no greater than 210 mm for the primary body and an overall length no greater than 1275 mm; The CG of the sonar transducer assembly body will be designed to be as low as possible for stability in lowering operations, with an upper limit of no greater than 35% of the length of the overall unit as measured from the bottom; The final fielded unit would incorporate a water thermocouple for measuring the water column temperature during lowering operations, a method for bottom proximity detection, a capability to protect itself during electrostatic discharge when lowered from a helicopter into the sea water, redundant depth sensing capabilities, angular orientation reporting relative to vertical, and a method for determining bearing orientation of the array; Acoustic elements would be physically or electronically steerable in the vertical plane; The unit design would be able to withstand operating depths to at least 2500 ft.
Work produced in Phase II may become classified.
PHASE I: Design a concept for a low-cost multi-frequency band sonar transducer assembly capable of supporting both ASW and AMCM mission sets. Create scale electronic models of the concept showing the integration of both capabilities within a single assembly, illustrate and explain conceptually how the assembly would be utilized for both ASW and AMCM missions in relation to the two (or more) primary frequency band capabilities. Demonstrate via analysis and simulation of the ability to use the mid-frequency band to cover traditional both inner and middle zone ASW through mono-static and multi-static methods combined with new technology and unique operating/processing methods. Via analysis and simulation, demonstrate the effectivity of the mid-frequency band and the higher frequency band for rapid detection of mines at various points in the water column including floating, moored, and bottomed types. Prepare a Phase II plan.
PHASE II: Develop a scale prototype of the sonar transducer assembly designed in Phase I for demonstrating physical sizing, fit, weight, CG, and mechanical functionality (not necessarily operable except for manual manipulation) to allow for demonstration of fit into a USN ASW-capable helicopter. Develop and demonstrate an acoustically functional and watertight representative prototype array in water, including development of an initial design specification for the sonar transducer. Initial demonstration and validation via computer modeling in full, or in part, will be considered if funding availability limits full hardware/software prototype construction. Prepare a Phase III commercialization/transition plan. It is probable that the work under this effort will be classified under Phase II.
PHASE III DUAL USE APPLICATIONS: Develop, build, and deliver a flight-worthy and fully functional sonar transducer assembly. Conduct full box level functional and environmental qualification (test and/or analysis), support field testing conducted by the USN, and support flight test operations on a USN MH-60R in both anti-submarine and mine-countermeasure scenarios. Create a system specification and drawing set for the final product. Verify through test compliance to specification and verification of modeling performed in Phase II. Develop and deliver high level concept of employment and operation. Assess and report on viability of using for mine-classification in addition to detection capabilities. Enhancements in underwater sonar systems could be applied to improved sonar systems used for offshore geographical exploration (mining, oil, etc.), marine surveys, and additionally could be beneficial in accelerating methods for search/rescue/recovery of personnel and equipment associated with ships and aircraft lost at sea.