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Fuel-Air Explosive Technologies from Dual-Use Materials


OBJECTIVE: Develop enabling technologies for a single event, fuel-air explosive (FAE) based on the liquid fuel, JP-10, used in propulsion systems. DESCRIPTION: There is a need for smaller weapons systems that will retain the lethal performance of the larger systems they will replace. One approach to miniaturizing ordnance is to use dual-use or multifunctional materials. Under this topic, residual JP-10 from the munition"s propulsion system would be used as a fuel-air explosive (FAE) to augment the blast performance of the standard warhead. These enhanced blast ordnance would be used in delivery vehicles that already carry JP-10 either low-speed UAV-based platforms powered by turbine engines or high speed cruise missiles powered by ramjet/scramjet engines. These propulsion systems have residual fuel in their fuel tanks as a safety margin, and fuel amounts can be significant if the actual cruise range is below the maximum cruise range. There are multiple technical challenges that must be addressed: (a) creating an ignitable vapor/aerosol cloud from a low vapor pressure fuel; (b) dispersing the cloud at the proper fuel-air concentrations (within the upper and lower flammability limits); (c) developing a single event ignition system rather than a two-stage system; and (d) developing a robust system that is functional at a wide variety of dispersal and ignition conditions. These challenges are briefly described below. Because JP-10 has a relatively low vapor pressure, it may be necessary to (a) pre-condition (e.g., heat) the fuel before dispersal, (b) develop a novel shock-heating concept, or (c) add a sensitizing agent to the JP-10 during dispersal. The proposal should discuss the system-level implications of the approach (e.g., preheating via integration into the delivery vehicle"s thermal management system, logistical compliance of the sensitizing agent). In single event FAEs, the fuel and ignition source are integrated and dispersed simultaneously or near-simultaneously; in a two-stage FAE, the fuel is dispersed first and then, after an appropriate time delay for cloud formation, the ignition system is activated. The time delay between events makes two-stage systems difficult to weaponize, particularly at high speed delivery (1000-3000 feet per second). A single event FAE might use a distributed ignition system that can be explosively dispersed with the fuel, such as a pyrotechnic material. The proposer should discuss the problems inherent to thermal ignition (versus shock ignition) if using this approach. It is preferable, although perhaps not essential, that the FAE detonates rather than deflagrates. If a deflagration concept is proposed, the fuel-air explosive must generate a lethal impulse. Selection between detonation and deflagration modes is preferred but not required. PHASE I: The contractor will develop the system concept or sub-system component through modeling, analysis, and breadboard development. Small-scale testing to show proof-of-concept is highly desirable. Merit and feasibility must be clearly demonstrated during this phase. PHASE II: Develop, demonstrate, and validate the component technology in a prototype based on the modeling, concept development, and success criteria developed in Phase I. Deliverables are a prototype demonstration, experimental data, a model baselined with experimental data, and substantiating analyses. PHASE III: Ordnance compatible with UAVs and cruise missiles. Smaller payloads for high weapon load-outs and internal carriage in stealth aircraft. REFERENCES: 1. Fan Zhang (editor),"Shock Wave Science and Technology Reference Library, Volume 4, Heterogeneous Detonation,"ISBN 978-3-540-88446-0, e-ISBN 978-3-540-88447-7, Springer Verlag, Berlin Heidelberg, 2009.
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