Aircraft Hydraulic Aircraft Hydraulic SystemsSystems

AIAA Design Group II

Basic Hydraulic SystemBasic Hydraulic System

Reference: http://www.allstar.fiu.edu/AERO/Hydr02.htm

•A valve is opened, the hydraulic flows into the actuator and presses against the piston, causing it to move and in turn move the attached control surface

General UsesGeneral Uses

Used for flight control, actuation of Used for flight control, actuation of flaps, slats, weapons bays, landing flaps, slats, weapons bays, landing gear, breaksgear, breaks

Provides the extra force required to Provides the extra force required to move large control surfaces in heavy move large control surfaces in heavy aerodynamic loads.aerodynamic loads.

General SpecificationsGeneral Specifications

Several different FluidsSeveral different Fluids• MIL-H-5606,   MIL-H-83282,   and MIL-H-81019MIL-H-5606,   MIL-H-83282,   and MIL-H-81019• General Temperature Ranges : -65°F to 295°FGeneral Temperature Ranges : -65°F to 295°F

Pressures:Pressures:• Airbus A380 has 5000psi hydraulic systemAirbus A380 has 5000psi hydraulic system• Typical commercial airline pressure is 3000 psiTypical commercial airline pressure is 3000 psi

•http://aerospace.eaton.com/news.asp?articledate=06/01/03&NewsCommand=ViewMonth

•http://www.tpub.com/content/aviation/14018/css/14018_178.htm

Problems with HydraulicsProblems with Hydraulics

HeavyHeavy High maintenance High maintenance

• Adds cost and creates a logistics Adds cost and creates a logistics problemproblem

Requires space (pumps, hydraulic Requires space (pumps, hydraulic lines, etc.)lines, etc.)

Possible Improvements Possible Improvements Electric ActuatorsElectric Actuators

• Consists of a small electric motor, pump Consists of a small electric motor, pump and actuator ram requiring about 1 pint and actuator ram requiring about 1 pint of hydraulic fluidof hydraulic fluid

• Flight tested by NASA’s Dryden Flight Flight tested by NASA’s Dryden Flight Research Center on a modified F-18.Research Center on a modified F-18.

• Provides significant weight savings by Provides significant weight savings by eliminating pumps and hydraulic lineseliminating pumps and hydraulic lines

• Also could decrease required Also could decrease required maintenancemaintenance

Reference: NASA Dryden Flight Research Center. News Release 98-84

Electro – Mechanical ActuatorElectro – Mechanical Actuator

Reference: Air Force Research Laboratoryhttp://www.afrlhorizons.com/Briefs/0006/VA9902.html

Impact on DesignImpact on Design

Need to allow sufficient space for Need to allow sufficient space for required hydraulic systemsrequired hydraulic systems

Weight of the system must be Weight of the system must be accounted foraccounted for