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Aerostat Communications Relay from Unmanned Surface Vehicle


OBJECTIVE: The objective is to increase the communications range between the Littoral Combat Ship (LCS) seaframes and Mission Package Unmanned Surface Vehicles (USVs) by developing a modular aerostat communications relay system for the RT-1944/U radio that is semi-autonomously deployed and retrieved from the LCS Unmanned Influence Sweep System USV. The modular aerostat communications relay system includes an aerostat with the RT-1944/U radio, and a launch and recovery mechanism. DESCRIPTION: The Navy Littoral Combat Ships (LCS) Minecountermeasure (MCM) Mission Package (MP) will include the Unmanned Influence Sweep System (UISS). Reference (1) provides an overview of the UISS. A key component of UISS will be a light-weight, high- speed Unmanned Surface Vehicle (USV) which will sweep minefields ahead of the underway LCS seaframes. Reference (2) contains high level descriptions of the UISS USV. The LCS platforms and the USVs will communicate with each other through the Multiple Vehicle Communications System (MVCS) which gives LCS MPs the capability to simultaneously communicate with multiple Unmanned Vehicles (UVs) by providing common data link and network communication services. The RT-1944/U radio has been selected for the current MVCS increment for Line of Sight (LOS) communications between the LCS and the UISS USV. The radio will also be used for the next increment which includes an Over the Horizon (OTH) communication requirement between unmanned vehicles and the LCS platforms. Reference (2) provides details about the radio. The current plan is to use helicopters and Vertical Take Off Unmanned Air Vehicles (VTUAVs) for the OTH relay links between unmanned vehicles and the LCS platforms. Both of these links have the disadvantage of limited time on station because of fuel consumption. In addition, a helicopter is a costly resource to use for a relay link, especially when it could be performing other missions. It is highly desirable to provide Over the Horizon (OTH) communications for a longer period of time than can be achieved with Unmanned Aerial Vehicle relays. For the next increment, and perhaps longer, no satellite communication solution is expected to be available that can support the MCM MP data rate requirement. Similarly, no antennas currently exist that are small enough to fit on unmanned vehicles and support the bandwidth required for satellite communication. Craft close to the water and subject to wave motion pose additional challenges to antenna design. Furthermore, military demand for satellite communications is high and will be provided on a priority basis. Consequently, an aerostat tethered to the UISS USV has been identified as a desirable solution for OTH communication with the LCS seaframe. Previous Navy investigation has indicated that an aerostat solution is feasible and that significant innovation will be needed to achieve it. Currently, no aerostat or similar tethered vehicle has been identified that is small enough or stable enough to be launched from a USV while carrying the radio. Once launched from the USV, an aerostat carrying the radio has the potential to provide a long term direct link to the ship. A small, tethered powered air vehicle could be an alternative solution to an aerostat, although its air time would be relatively more limited and the power source, depending on its location, would add additional weight to the vehicle or tether system, possibly beyond the equipment needed to provide power to operate the radio. The USV will be launched and recovered from the LCS, and the aerostat will be semi-autonomously deployed and elevated from, tethered to, and, ideally, recovered by the USV. Once the USV is launched from the LCS, an operator aboard the LCS will control the USV remotely through the MVCS and will remotely command deployment and retrieval of the aerostat. Given the technical challenges involved, retrieval and stowage of the aerostat itself may be more difficult, slow, and energy consuming than desirable. A goal is to retrieve the radio itself. Jettisoning of the aerostat and any associated equipment should not pose danger to marine life or pose an environmental hazard. An aerostat to be jettisoned should be of low enough cost to make that option acceptable in comparison to the cost of retrieval. A retrieved or jettisoned aerostat should not interfere with the operation of or threaten damage to the USV. The aerostat must be launched while carrying the radio and handing the weight of the tether. While an operator on an LCS platform will provide commands to the USV through the MVCS, the actual mechanical operations must be done unmanned. Power must be provided to the radio. The aerostat communications relay system, including all components, must be designed for minimal weight and storage. Weight, including payloads, is important because of its effect on fuel use and, therefore, mission length. Similarly, fuel consumption must be considered in development of the operation of the lifting and retrieval mechanisms and the process for maintaining aerostat altitude. Since the final UISS USV design has not been settled on, the whole system should be modular and adaptable. Such flexibility will enhance its potential for use on other USVs. The Phase I feasibility study and Phase II prototype development and demonstration may be done from a craft similar in size to the planned UISS USV. The demonstration craft may be manned so long as the aerostat operation is demonstrated autonomously. Integration into the UISS USV and operation though the MVCS would occur in Phase III. The USV and aerostat communications relay shall stay operational for four days or longer without any planned maintenance such as refueling the USV or, for instance, adding helium to the aerostat if that gas were part of the solution. The communications relay shall operate and maintain communications between the LCS and unmanned systems in Sea State 3 or greater. The relay shall operate at an altitude of 500 feet or higher with the RT-1944/U radio system installed. PHASE I: The company will develop concepts for an aerostat communications relay system meeting the requirements described above. The company will demonstrate the feasibility of the concepts in meeting Navy needs and will establish that the concepts can be feasibly developed into a useful product for the Navy. The company will demonstrate the feasibility of the concept by specifying material components to be considered and modeling and simulation of the high risk procedures. The company will provide a Phase II development plan with performance goals and key technical milestones that will address technical risk reduction. PHASE II: Based on the results of Phase I and the Phase II development plan, the company will produce a prototype aerostat communications relay system. The company will test and evaluate the prototype system on a craft similar in size and capacity to the planned UISS USV to determine its capability to meet the performance goals defined in Phase II development plan and the Navy requirements for an OTH aerostat communications relay system. The company shall demonstrate the prototype system to the government and evaluate the results. The company will use the evaluation results to refine the prototype into a pre-production design that will meet Navy requirements. The company will prepare a Phase III development plan to transition the technology to Navy use. PHASE III: If Phase II is successful, the company will be expected to support the Navy in transitioning the technology for use in the MCM MP UISS USV. The company will need to work with the supplier of the UISS USV to integrate the system onto the USV. The company will support test, validation, certification, and qualification of the system. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Long-range communications from USVs to bases has applications to homeland security, oceanographic research, and, potentially, protection of commercial shipping. REFERENCES: 1. Program Executive Office (PEO) Littoral Combat Ships (LCS) Fact Sheet."Unmanned Influence Sweep System." Downloaded 15 April 2012. 2. Ashton, CAPT Duane."Unmanned Maritime Systems Overview."Presentation to The Maritime Alliance Conference. 17 November 2010. Search on the title or use the following link:"Surface Mine Countermeasure (SMCM) UUV Payload Development ..."Downloaded 7 April 2012. 3. Harris Corporation. Documentation for SeaLancetTM RT-1944/U Radio. Downloaded 15 April 2012.
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