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Future Air Force intelligence, surveillance, and reconnaissance (ISR) platforms, such as high-altitude Uninhabited Aerial Vehicles (UAV), may drastically change the requirements of aircraft power systems. For example, there are potential interactions between large pulsed-power payloads and the turbine engine that could compromise the operation of the power system within certain flight envelopes. Until now, the development of large-scale, multi-disciplinary (propulsion, electrical, mechanical, hydraulic, thermal, etc.) simulations to investigate such interactions has been prohibitive due to the size of the system and the computational power required. Moreover, the subsystem simulations that are developed separately often are written in different commercial-off-the-shelf simulation programs.

The use of electric actuators, such as electro-hydrostatic actuators (EHA), for moving flight control surfaces is an integral part of the more-electric aircraft (MEA) concept to replace inefficient, centralized hydraulic systems with power-on-demand electrical systems. Removing the centralized hydraulic system will, however, eliminate an effective heat transfer network, thus resulting in an aircraft with less overall heat to reject but with localized “hot spots.” Under the Air Force MEA Thermal Management program, Northrop Grumman is assessing the cooling requirements for an MEA version of the F/A-18 aircraft through detailed thermal modelling and computer simulation. Lumped-parameter EHA thermal models have been developed to characterize component heat transfer within their operating environments using realistic actuator duty cycles generated from six-degree-of-freedom (6-DOF) aircraft simulation.