An Advanced Endothermic Fuel System for Hypersonic Propulsion

ABSTRACT: The development of weapons that can travel at hypersonic speeds is becoming a high priority to the US Air Force. Continued development of these vehicles relies on the ability to cool the combustor using the fuel. The cooling capacity of kerosene-based fuels is low even with endothermic cracking reactions. Increasing the fuel cooling capacity by raising the fuel flow or allowing it to reach higher temperatures is not practical because the additional fuel would have to be dumped overboard or lead to coke formation. Therefore, there is a strong need to develop new endothermic fuels and reactors that can deliver substantially higher heat sink capacities. In this Phase I project, Reaction Systems will identify a new fuel consisting of a single hydrocarbon or a blend that can undergo other endothermic reactions and produce heat sink capacities that are higher than are available with JP-7. The new hydrocarbons will be readily available and likely less expensive than JP-7 and the higher heat sink capacities will be obtained at lower temperatures, where coking will not occur. Reaction Systems will also design a heat exchanger/reactor that will maximize heat transfer and be constructed in Phase II. BENEFIT: The technology developed in this project will be particularly well-suited for the new Air Force High Speed Strike Weapon (HSSW) program. This program represents a unique opportunity to develop a new, inexpensive endothermic fuel with higher heat sink capacity to sustain higher flight Mach numbers while also providing improved ignition and flameholding properties compared to JP-7. Because scramjet power represents new technology, it is difficult to estimate the size of the market that these vehicles ultimately might represent. However, based on the Air Launched Cruise Missile (AGM-86) program and the later AGM-129 Advanced Cruise Missile program, which built over 1700 missiles at a cost of about $1M each, we can probably anticipate an ultimate production on the order of 1000 to 2000 units. The current cost of JP-10 (a synthetic high density missile fuel) is about $16 per gallon, while the costs of typical high-purity hydrocarbon-based commercial chemicals are on the order of $6 per gallon in bulk. Even at a cost of $32 per gallon for an advanced endothermic fuel blend, a missile fuel capacity of approximately 100 gallons each suggests a total fuel cost of only about $3.2M to $6.4M out of a $1B to $2B overall production program. The cost of the heat exchanger/reactors and other required thermal management system hardware components could easily exceed the fuel cost by a factor of ten, suggesting that the total potential market for our products could be on the order of $32M to $64M to supply a single HSS missile production run, or ~$5M/yr revenue stream over a ten year period. This could become much larger if hypersonic flight applications grow beyond missiles.