N151-003 TITLE: Low Complexity Suspension System for Amphibious Vehicles

TECHNOLOGY AREAS: Ground/Sea Vehicles

ACQUISITION PROGRAM: Program Manager Advanced Amphibious Assault (PM AAA)

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 5.4.c.(8) of the solicitation. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a minimally complex suspension system for up to 40 ton amphibious vehicles capable of moving the wheels or tracks into a position to minimize drag while moving through water for the purpose of improving speed and overall suspension system reliability.

DESCRIPTION: The United States Marine Corps is in the process of developing and procuring armored tracked and wheeled troop carriers designed to operate over harsh off-road terrain and in oceans and rivers (Ref. 1). Currently, amphibious vehicle capabilities are limited due to competing requirements: 1) water mobility, 2) combat effectiveness, 3) carrying capacity, and 4) survivability. For these reasons, light-weight, durable and affordable components and sub-systems which have the potential to maximize the overall system capability are viewed as being highly desirable as technology development initiatives. The suspension system for a high-speed amphibious vehicle needs to accommodate both land and sea travel. This dual mode of operation presents complex engineering challenges. The suspension system technology implemented on the Expeditionary Fighting Vehicle (EFV) reflects the current state-of-the-art for tracked amphibious vehicles. This system used high pressure Hydropneumatic Suspension Units (HSU) that pivot aft to lift the track up to the level of the vehicle’s flat bottom. As can be seen in Reference 1, the EFV was basically a flat bottom brick shape with an extendable bow. In water mode, it retracted the vehicle’s track to minimize water drag and, in land mode, the HSU rotated down to provide 16 inch ground clearance while moving at up to 45 mph across country. While it met performance requirements, it was viewed as: very complex (20+ major components hundreds of feet of piping); requiring a very high (35,000 pounds per square inch (PSI) max) hydraulic pressure system; expensive to acquire; having a projected Mean Time Between Failure (MTBF) of 229 hours which was partially attributed to the complexity of the system.

The Marine Corps is interested in innovative approaches in the development of a suspension system for a 40 ton amphibious vehicle capable of traversing the land portion of the Marine Corps Mission Profile while being retractable to zero ground clearance while the vehicle is operating in the water. Proposed concepts (as a system) should weigh less than 5,000 pounds (lbs.), cost less than $800,000 to acquire and have an improved projected MTBF. Weight, cost, and complexity should not include track, road wheels, or support rollers for tracked systems nor wheels for wheeled systems. For the purpose of technology development and demonstration, proposers should use the EFV geometries and operating profiles in the development of their concepts (Ref 2, 3). Proposed concepts should:

- Address the ability to function in extreme operating environments which include but are not limited to -25 degrees Fahrenheit (°F) to +120°F, hot dessert blowing sand, full salt water immersion and immersion in petroleum based liquids.
- Allow for terrain traverse with combined 3 g-force (G) vertical and 0.7 G horizontal load on suspension station, racking load at diagonal corners for 1 G vertical load, North Atlantic Treaty Organization (NATO) tree impact (5" tree at 32 kilometers per hour (kph)-8365 pound equivalent static load), and fatigue loads for 30 year vehicle life.
- Be capable of withstanding, without performance degradation, all loads imparted in grounding from a speed of 9 knots.
- Not allow ground pressure to exceed 70.67 kiloPascals (kPa) (10.25 psi) and shall have a ground clearance of no less than of 15 inches.
- Support steering in the forward and reverse directions on 40 percent side slopes and ascending, descending, starting, and stopping on a dry hard surfaced longitudinal slope up to and including 60 percent grade in both forward and reverse direction.
- Allow the vehicle to cross a gap no less than 2.44 meters (8 feet) across.
- Robust and survivable within the varied operating environment (Ref. 4 and 5) and able to withstand vehicle vibration and ballistic shock requirements (Ref. 4).

PHASE I: The company will explore the design and development of advanced suspension system concepts for a light-weight, lower-cost, low-complexity, vehicle suspension system alternative for next generation amphibious vehicles. The company needs to consider the operating environment in which the suspension system will be exposed. The company will demonstrate the feasibility of the concept(s) in meeting Marine Corps’ needs and will establish that the concept can be developed into a useful product for the Marine Corps. Feasibility will be established by material testing and analytical modeling as appropriate. 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 upon the results of Phase I and the Phase II Proposal, the company will develop a scaled prototype of the suspension system for evaluation. The prototype will be evaluated to determine its capability in meeting the performance goals established for the Marine Corps’ amphibious vehicles improved vehicle suspension system as identified above. System performance will be demonstrated through prototype evaluation and modeling or analytical methods over the required range of parameters. Evaluation results will be used to refine the prototype into a design that will meet Marine Corps requirements. Working with the Marine Corps, the company will prepare a Phase III development plan to detail the strategy for transitioning the technology for Marine Corps use.

PHASE III: If Phase II is successful, the company will be expected to support the Marine Corps in transitioning the suspension system for Marine Corps use. Working with the Marine Corps, the company will integrate their prototype vehicle suspension system into a vehicle for evaluation to determine its effectiveness in an operationally relevant environment. This technology is directly applicable to large military vehicles such as the Marine Corps Amphibious Combat Vehicle (ACV) and the Army’s Armored Multi-Purpose Vehicle (AMPV). The company will support the Marine Corps for test and validation to certify and qualify the system for Marine Corps use. The company will develop manufacturing plans and capabilities to produce the system for both military and commercial markets.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Successful development and characterization of a suspension system has direct application to various military and commercial applications such as amphibious rescue vehicles. Reductions of weight and complexity in the suspension can be of substantial value.

REFERENCES:
1. "Expeditionary Fighting Vehicle." Last modified 14 August 2014. Retrieved from: http://en.wikipedia.org/wiki/Expeditionary_Fighting_Vehicle

2. "Expeditionary Fighting Vehicle (EFV)." Last modified 26 August 2012. Retrieved from: http://www.globalsecurity.org/military/systems/ground/aaav-specs.htm

3. Walker, M., "United States Marine Corps Operational Maneuver From The Sea." Retrieved from: http://www.acq.osd.mil/log/mpp/cbm+/Briefings/Monty_EFV_AG_working_group_overview_Mar08_resize.pdf

4. MIL-STD-810G Environmental Test Methods and Engineering Guidelines. Retrieved from: http://www.everyspec.com/MIL-STD/MIL-STD-0800-0899/MIL-STD-810_13751/

5. MIL-STD-889B Dissimilar Metals. Retrieved from: http://www.everyspec.com/MIL-STD/MIL-STD-0800-0899/MIL_STD_889B_955/

KEYWORDS: Amphibious vehicle; suspension system; retractable suspension; tracked vehicle; wheeled vehicle; hydrodynamic efficiency

** TOPIC AUTHOR (TPOC) **

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