Various Challenges Of Aircraft Hydraulic Design

The aircraft hydraulic systems can be challenging for engineers owing to the many constraints associated with it. Whether it is designing for plant or in application, the encountered challenges disperse evenly. Going back to history, the hydraulic technology gained importance during the expanse of Second World War. However, aircraft hydraulic systems came into the picture precisely while managing critical operations and safety of airliners and military craft. 

Taking the concept of modern aircraft, some of the places wherein hydraulics come to the fore include the following parts:

• primary flight controls, flap/slat drives
• landing gear
• nose wheel steering,
• thrust reversers, spoilers, rudders,
• cargo doors and emergency hydraulic-driven electrical generators.

Apart from the above mentioned, some of the military aircraft also employ the hydraulic technique in gun drives, weapons-bay doors and fan heat exchangers that are driven by hydraulic motor. From among the several factors that must be addressed aircraft include regulation of both internal and ambient temperature extremes. The hydraulics should be in accordance with the following elements of the machinery:

• weight
• speed
• materials—single acting hydraulics cylinders
• reliability, fluid compatibility
• redundancy

The fundamental challenges faced to employ the hydraulics technology in aircraft are elaborated as under:

1. Pressure and Temperature

The estimated pressures on the aircraft hydraulic systems escalate higher than on many industrial applications. The general range varies from 1,500 to 2,000 psi range. The estimated velocity of commercial airliners is 3,000 psi, with military planes using 4,000 psi systems. Although in some exceptions some of the military aircraft have moved up to 5000 psi as well. 
The impulsion for greater pressures comes from space considerations. The need for the light weight is deliberate so that the actuators can swirl higher torque forces and induce power from the smaller envelope as well.

2. Managing the fluids in high and low temperatures

As compared to the industrial fluids, the one used in aircrafts has a relatively flat viscosity. The resistance of liquids to sheer force when compared to the temperature curve is substantially thin. In addition, these fluids must be fire resistant. One of the prominent characteristics of these fluids is that they remain in their liquid state even at a temperature of 65° F, a temperature at which water and vegetable based oils will solidify.

3. Component and system reliability

The general maintenance of fluid conditions, maintenance, and filtration is given more emphasis on aircraft. Under industrial applications the PLC is the operating system, the question of application management arises while working on the mobile equipment. The reliability is so critical on aircrafts system, that focus is need to be thrown on everything, for instance, redundant systems, maintenance schedules and inflexible guidelines.

4. Other sundry factors

The aspect of noise control is restricted to the hydraulics if the aircraft. It makes sense as tweaking a system to manage noise decibels is immaterial when the plane’s engines can easily wear off any noise effectively through the hydraulics. However, in recent years the aircraft designs have been accustomed to take off and land in a quieter way appeasing the communities in the proximity of the airport. Thus on uniting all aspects, managing the noise becomes an important aspect to consider in aircraft designing.