Hydraulic power requirements of military aircraft have increased significantly over the years. This has brought to the surface such issues as how best to manage the higher power requirements, which in many cases exist for only a small part of the duty cycle duration, and also how to minimize the system losses (heat rejection), which in turn can result in reduced cooling requirements.
This paper summarizes some of the available data on the power requirements of military aircraft, discusses the inefficiencies of higher pressure systems being considered for high horsepower requirements, and describes the available approaches for better management of the high pressure/horsepower requirements, with respect to improving the operating efficiency of such systems.
The paper draws heavily on the results of an Advanced Development Program (ADP) administered by the Wright Laboratories - US Air Force, and conducted by McDonnell Aircraft Company (McAir) between 1986 and 1990, to illustrate the benefits that can be realized with variable pressure system designs to meet the high horsepower challenge. The technology to enable such system designs is available today, and is a case of beneficial synergism that can be realized between the hydraulics and the electronics technologies on advanced aircraft.