Aircraft Hydraulic Systems

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Aircraft Hydraulic Systems
AIAA Design Group II
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Basic Hydraulic System

• 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

Reference http//www.allstar.fiu.edu/AERO/Hydr02.
htm
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General Uses

• Used for flight control, actuation of flaps,
  slats, weapons bays, landing gear, breaks
• Provides the extra force required to move large
  control surfaces in heavy aerodynamic loads.

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General Specifications

• Several different Fluids
• MIL-H-5606,   MIL-H-83282,   and MIL-H-81019
• General Temperature Ranges -65F to 295F
• Pressures
• Airbus A380 has 5000psi hydraulic system
• Typical commercial airline pressure is 3000 psi

• http//aerospace.eaton.com/news.asp?articledate06
  /01/03NewsCommandViewMonth
• http//www.tpub.com/content/aviation/14018/css/140
  18_178.htm

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Problems with Hydraulics

• Heavy
• High maintenance
• Adds cost and creates a logistics problem
• Requires space (pumps, hydraulic lines, etc.)

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Possible Improvements

• Electric Actuators
• Consists of a small electric motor, pump and
  actuator ram requiring about 1 pint of hydraulic
  fluid
• Flight tested by NASAs Dryden Flight Research
  Center on a modified F-18.
• Provides significant weight savings by
  eliminating pumps and hydraulic lines
• Also could decrease required maintenance

Reference NASA Dryden Flight Research Center.
News Release 98-84
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Electro Mechanical Actuator
Reference Air Force Research Laboratory http//ww
w.afrlhorizons.com/Briefs/0006/VA9902.html
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Impact on Design

• Need to allow sufficient space for required
  hydraulic systems
• Weight of the system must be accounted for