Advanced Arresting Gear Cable for Lighter Weight and Longer Service Life
Navy SBIR 2014.2 - Topic N142-107
NAVAIR - Ms. Donna Moore - email@example.com
Opens: May 23, 2014 - Closes: June 25, 2014
N142-107 TITLE: Advanced Arresting Gear Cable for Lighter Weight and Longer Service Life
TECHNOLOGY AREAS: Materials/Processes
ACQUISITION PROGRAM: PMA 251
RESTRICTION ON PERFORMANCE BY FOREIGN NATIONALS: This topic is "ITAR Restricted". The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120-130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign nationals may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign national who is not in one of the above two categories, the proposal may be rejected.
OBJECTIVE: Develop an arresting gear cable with half the weight and double the service life of the current steel cable.
DESCRIPTION: Aircraft are recovered aboard aircraft carriers by means of the aircraft tailhook engaging a cable which is connected to an arresting gear engine below the flight deck. The arresting gear engine absorbs the aircraft’s kinetic energy, stopping the aircraft on the flight deck. The cable is a critical component to successful recoveries. The current cable is steel and is approximately 65 percent of the effective mass of the current arresting gear system.
The Navy needs a lighter weight replacement to the existing steel cable with a higher strength-to-weight ratio than steel. Such a cable would significantly improve the performance of the arresting gear engine, enabling increased bring-back weight of the aircraft, reduced wind-over-deck required for recovery, and increased safety margin. This is especially important in order to push the trade space envelope for future aircraft, i.e. allow for heavier aircraft with faster approach speeds to operate off of carriers.
The objectives of the new cable would be to double the service life of the current cable with a maximum weight of 2 pounds (lbs) per foot and a minimum tensile strength of 220,000 lbs before breaking. The cable must also be able to be terminated.
Service life is defined by the number of cycles on a two-sheave testing machine. The current cable achieves a minimum of 7,600 cycles at 98,000 pound tension wrapped around 28 inch sheaves. The new cable must achieve a minimum of 15,200 cycles under the same conditions. The current arresting cable is 1-1/2 inches in diameter and 1,150 feet in length; proposals must address whether the new cable can be manufactured in adequate lengths. A different cable diameter could be considered (i.e., a cable that is not compatible with current sheave throat dimensions), if the benefits are significant enough to justify a service change to the arresting gear. Because the cable must wrap around multiple sheaves, cable construction must be such that the individual strands can move freely with respect to each other to maximize flexibility and bend-over-sheave performance.
Cable terminations must have an efficiency of 95 percent, i.e., have a tensile breaking strength equal to 95 percent of the breaking strength of the cable, with resistance to tensile load distributed equally over all strands. Cable termination efficiency may be traded off for increased tensile strength such that the combined cable/terminal assembly has a minimum tensile strength of 210,000 lbs. Special consideration will be given to proposals that can exceed this strength requirement, thereby increasing our operating factor of safety. Past research and testing have shown that certain synthetic material fibers compress in the cross-sectional direction under tensile load and exhibit a tendency to pull away from epoxy-filled sockets. A termination solution would need to address this phenomenon, either by developing/testing a fiber that does not compress, by proposing a novel epoxy or termination methodology. For novel termination methods, in the field termination technique should be considered to allow shipboard terminations while underway.
Approximately 250 feet of the cable will be subject to abrasion against flight deck non-skid during every arrestment cycle (Non-skid spec: MIL-PRF-24667C). Any new cable must be resistant to non-skid abrasion over the service life of the cable. Additionally, the cable is exposed to a salt-water environment and other elements such as flight deck cleaners, fuel, hazardous chemicals, and heat from aircraft exhaust. Preservation of the cable material should be considered. The current cable has exposure limitations and must be removed under special circumstances where chemical exposure is unavoidable. Therefore survivability against every chemical is not a requirement; however an understanding of compatible and incompatible materials to develop necessary procedures is highly desirable.
The references document previous testing with synthetic materials, but the topic is open to any technology approach.
PHASE I: Define technical issues related to the cable concept in the arresting gear application. Determine the feasibility of the concept by proving whether the cable will meet the strength, service life, weight, termination and abrasion resistance objectives through analysis and/or targeted lab demos that address specific technical issues.
PHASE II: Develop full scale prototype cables with terminations. Test service life on a two sheave tester. Test tensile strength on a tensile tester. Test abrasion resistance. Propose shipboard termination procedure. Address manufacturability and provide defendable estimates for production cost. Address lubrication and preservation of the cable to protect it from salt water, aviation fuel, flight deck cleaner, and aircraft exhaust heat.
PHASE III: Qualify the cable through testing at Lakehurst shore-based arresting gear facilities. Build production quantities of cable for transition to the carrier fleet.
PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Cables of this size and magnitude find numerous applications in the commercial sector, including bridges, elevators, mining, amusement parks, ski lifts, ship moorings, and building construction/cranes.
2. Sloan, F., Bull, S., and Longerich, R., 2005, Design Modifications to Increase Fatigue Life of Fiber Ropes. OCEANS,2005. Proceedings of MTSS, 1, 829-835, doi:10.1109/OCEANS.2005.1639856.
3. Sloan, F., Nye, R., Liggett, T., 2003, Improving Bend-over-Sheave Fatigue in Fiber Ropes, OCEANS 2003, Proceedings, 2, 1054-1057, doi:10.1109/OCEANS.2003.178486.
KEYWORDS: Advanced Materials; Cable Termination; Arresting Gear Cable; Advanced Fibers; High Tensile Strength; Bend Over Sheave