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Compact, High Performance Engines for Air Launched Effects UAS

Description:

TECHNOLOGY AREA(S): Air Platform

OBJECTIVE: Develop and demonstrate low volume, high performance engine systems to power Air Launched Effects (ALE) unmanned aerial systems (UAS) for increased operational capability.

DESCRIPTION: Tactical requirements for ALE unmanned aerial systems are exceeding current capabilities for performance (payload, range/endurance), low noise capability, reliability, maintainability, and supportability. Mission requirements such as extended range/endurance, increased power, low altitude operation without detection, and high reliability are becoming paramount. These requirements are not currently fully realized with conventional rotary, internal combustion, or turbine-based propulsion. Electrical power requirements for advanced payloads is also increasing, which adds weight to the air vehicle. Current UAS conventional engines tend to be noisy, which can limit UAS operational capabilities. Various advanced engine concepts offer the potential for significantly increased power to weight/volume ratio. The objective of this topic is to develop advanced, small engines (approximately 10-30 horsepower) which can fit in a defined installation envelope while having low noise characteristics and low specific fuel consumption (threshold 1.2 lb/hp-hr, objective 0.6 lb/hp-hr).The threshold size for the installation envelope is no larger than 13 inch height by 10 inch width by 21 inch length, while the objective size is 10 inch height by 10 inch width by 21 inch length. The output shaft should be aligned parallel to the length axis. Specific power goals for proposed engines (including the weight of all ancillaries required for operation such as control systems, cooling systems, gearbox (if required to meet output speed below), etc.) are .5 hp/lb threshold and 1.5 hp/lb objective. Reliability goals for proposed engines includes mean time between overhaul (1000 hours threshold, 2000 hour objective) and mean time between essential function failure (1000 hours threshold, 2000 hour objective).Additional key capabilities include the ability of the engine to operate off of heavy-fuel (JP-8, diesel, and alternative fuels) and ability to provide power to electrical payloads (1 kW). Output shaft design speed should be 4000-7000 rpm.

PHASE I: During Phase I effort, all major components of proposed engine concepts should be, as a minimum, designed and validated via either modeling or subscale testing to substantiate the ability to provide adequate power for propulsion, fuel consumption for endurance, as well as meeting reliability, specific power, and volume goals.

PHASE II: Phase II will fully develop, fabricate, and demonstrate a demonstrator engine system in a ground test environment.

PHASE III: Phase III options should include endurance testing and integration of the enhanced propulsion system into an ALE UAS airframe and demonstrate the performance of the system with flight testing in an ALE mission environment.

KEYWORDS: unmanned aerial system, propulsion system, heavy fuel engine, power to weight ratio, fuel efficiency, low noise

References:

1. Boretti, Albert. “Modeling Unmanned Aerial Vehicle Jet Ignition Wankel Engines with CAE/CFD.” Advances in Aircraft and Spacecraft Science, vol. 2, no. 4, 8 Apr. 2015, pp. 445–467., doi:10.12989/aas.2015.2.4.445.; 2. E. M. M. D. Cinar, G. A methodology for sizing and analysis of electric propulsion subsystems for unmanned aerial vehicles. In AIAA SciTech, San Diego, California, 2016.; 3. Merical, K., Beechner, T., and Yelvington, P., "Hybrid-Electric, Heavy-Fuel Propulsion System for Small Unmanned Aircraft," SAE Int. J. Aerosp. 7(1):126-134, 2014, URL: https://doi.org/10.4271/2014-01-2222; 4. Schomann, Joachim. “Hybrid-Electric Propulsion Systems for Small Unmanned Aircraft.” TECHNISCHE UNIVERSITÄT MÜNCHEN, 2014.

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