Air Cushioned Vehicle Erosion Resistant Coatings

Navy SBIR 24.1 - Topic N241-032
NAVSEA - Naval Sea Systems Command
Pre-release 11/29/23   Opens to accept proposals 1/03/24   Now Closes 2/21/24 12:00pm ET    [ View Q&A ]

N241-032 TITLE: Air Cushioned Vehicle Erosion Resistant Coatings

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Sustainment

OBJECTIVE: Develop coatings suitable for metal and marine composites to improve durability, decrease maintenance time and costs, and improve craft operational availability.

DESCRIPTION: Landing Craft, Air Cushion (LCAC) and Ship-to-Shore Connector (SSC) are Air Cushion Vehicles (ACVs), or "hovercraft", providing amphibious transportation of equipment and personnel from ship-to-shore and shore-to-shore. Erosion has been an antagonist for the ACV industry for many years. In operation, ACVs produce high airflow rates at speeds up to 300 mph across mostly composite components and surfaces. This massive amount of air flow can be saturated with saltwater and sand particulates. ACV components are also exposed to constant vibrations, high winds, impacts, and other foreign object debris. ACVs require erosion protection to cover large internal composite surfaces while minimizing both cost of acquisition and manpower for installation and maintenance. After a comprehensive survey of the industry, multiple commercial products have been attempted with no viable solution found. The internal flow surfaces on the craft that must be preserved from erosion include the bow thruster nozzle, upper lift fan volute, lower lift fan volute, propulsor shroud, propulsor stators, and rudders. As each component is custom and designed specific to its location, it must maintain its shape and composition. Figures and dimensions of these components can be found in Reference 4 linked below. The Navy has researched and evaluated multiple erosion coatings and tapes with marginal success in the harsh environment. Current solutions are difficult to apply and repair in the field. The Navy is seeking an optimized erosion protection solution to decrease maintenance and inspection intervals on all ACV composite surfaces, increasing mission efficiency and readiness. This product solution should be manageable for the onsite maintainers to reapply and repair when needed, including inside an amphibious ship’s well deck or on an isolated beach in a deployed environment. A successful coating technology must bond to all contact surfaces and not present the possibility of separating or delaminating, causing further damage to other components. A solution that meets all ACV erosion requirements would result in lowered overall maintenance effort and cost.

PHASE I: Develop a concept for erosion prevention for ACVs that meets the requirements as described above. Demonstrate the feasibility of the concept in meeting Navy needs. Demonstrate that the durable erosion prevention application can be readily and cost-effectively manufactured through standard industry practices by material testing and analytical modeling. The Phase I Option, if exercised, should include the initial layout and capabilities to demonstrate the application in Phase II.

PHASE II: Based on the results of the Phase I effort and the Phase II Statement of Work (SOW), develop and deliver an erosion prevention application that meets the requirements in the Description. A production representative application will be installed on an actual ACV component or appropriate test platform for durability and wear testing. The technology will be evaluated and compared to other erosion prevention methods to determine its ability to meet specified requirements. These evaluation results will be used to refine the erosion prevention application into a design that will meet ACV Craft Specifications. Prepare a Phase III development plan and cost analysis to transition the technology to Navy use.

PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the erosion prevention application for use on the ACV program. The satisfactory ACV erosion prevention method will have private sector and commercial potential for hovercrafts of this scale operating in the near-shore or on-shore environment, which are all currently struggling with erosion prevention. Commercial applications include ferries, the oil and mineral industry, cold climate research and exploration. Other industrial and military machinery with high airflow could also benefit from technologies developed during this effort.

REFERENCES:

  1. Brunton, J.H. "A Discussion on Deformation of Solids by the Impact of Liquids, and its Relation to Rain Damage in Aircraft and Missiles, to Blade Erosion in Steam Turbines, and to Cavitation Erosion." Royal Society, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, Vol. 260, No. 1110, Jul. 28, 1966, pp. 161-167. https://royalsocietypublishing.org/doi/10.1098/rsta.1966.0031
  2. Bastian, Andy. "Aircraft Radome and Leading Edge Erosion!" Industrial Drone Services, June 16, 2014. https://www.linkedin.com/pulse/20140616162845-316886946-aircraft-radome-and-leading-edge-erosion
  3. Rowbotham, Jim. "Erosion Protection of Aircraft Radomes and Leading Edges - Protect Your Asset and Your Image." April 23, 2016. https://www.linkedin.com/pulse/erosion-protection-aircraft-radomes-leading-edges-your-rowbotham?trk=pulse-article
  4. Air Cushioned Vehicle Erosion Resistant Coatings, Figures and Dimensions of Components navysbir.com/n24_1/NAVSEA-Erosion_Resistant_Coatings.pdf

KEYWORDS: Air Cushion Vehicle (ACV); Ship-to-Shore Connector (SSC); Landing Craft; Air Cushion (LCAC); Foreign Object Debris; High Velocity Airflow


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Topic Q & A

1/23/24  Q. Do you have any preference on the evaluation metrics?
   * Mass erosion, ‹Surface Profilometry, Contact Angle, ‹Taber abrasion are all suitable tests to evaluate performance during development.
   A. Mass erosion rate, weight, and failure mechanism are important evaluation metrics. But they are not exclusive. If the technology has a low overall wear rate, but fails or separates from the substrate quickly after a larger impact, then that material behavior is important and should be considered. Overall effectiveness for protection and field reparability is most important.
1/23/24  Q. Is a multi component system allowed?
   A. Yes, different areas of the craft may require different technologies, or a single area may require multiple components and/or materials.
1/22/24  Q. • What support equipment are available for erosion protection applications away from port?
• Do the Topic sponsors envision an erosion protection kit?
• Are there any known limitations for application of a novel coating solution (e.g., tools and equipment related, and/or corrective maintenance time goals (mean time to repair)?
   A. • Minimal. Deployed craft are required to bring all necessary field repair equipment and special tools. Space for that equipment competes with other, higher priority parts and repair tooling. Successful field repair kits are self-contained, with shelf lives >12 months.
• The initial erosion protection is intended to be installed at the organizational level where more industrial capability is available. “Kits” would only be necessary to repair damage to craft when they are deployed abroad, within a well deck ship or on an unimproved beach.
• Material applications that require cure time should not exceed 24 hours. Lower time is better. Heat guns, spatulas, grinders, etc. are available options, but may be minimally available in the field. Hardware installation is limited to common hand tools.
1/18/24  Q. Is metallic coating, such as Ni, Ti shell, etc., allowed for this topic?
   A. Yes. Solutions such as thin NiCo can perform well in the environment, but are more challenging to deploy and repair in the field. Also, extreme care must be taken when installing shells or plating onto, or near propulsor or lift fan rotors, wear erosion is most prevalent.
1/18/24  Q. Can you provide the expected Specs on erosion testing (like blasting, etc)? Was there a commercial testing spec that the Navy tried?
   A. The Navy has used MIL-STD-3033 for particle evaluation, and ASTM G73 for rain/spray impingement evaluation. The specific parameters for the tests, i.e. particle and droplet size, airspeed, etc. is specific to the area of the craft.

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