Aircraft control systems

In electronics and communications, the drivers are the need for further miniaturization, higher performance, and new optical technologies that provide entirely new products. For example, in aircraft, control systems have progressed from mechanical hydraulic components to fly-bywire electronic systems to the new concept of fly-by-light optical systems. This progression has depended on the development of the appropriate materials to design the performance systems. 

Uses. Antifoaming agent plasticizer for cellulose esters, lacquers, plastic, and vinyl resins component in hydraulic fluids for aircraft control systems... 

Sneak circuit analysis is usually performed with complex computer codes and is very expensive. It only becomes cost-effective on subsystems that are safety critical, such as an aircraft control system. Obviously, sneak circuit analysis should be teamed with the software safety analysis tools discussed in Chapter 8. This is a very powerful combination, but not cheap, certainly, very important for the most safety-critical circuits of very high-risk systems. 

BeryUium is important as a sensor support material in advanced fire-control and navigation systems for military heflcopters and fighter aircraft utilizing the low weight and high stiffness of the material to isolate instmmentation from vibration. It is also used for scanning mirrors in tank fire-control systems. 

Fitts, P. M., Jones, R. E. (1947). Analysis of Factors Contributing to 460 "Pilot Error" Experiences in Operating Aircraft Controls. Reprinted in H. W. Sinaiko (Ed.) (1961), Selected Papers on Human Factors in the Design and Use of Control Systems. New York Dover. 

Another example of the importance of the VI is the need for a high viscosity index hydraulic oil for military aircraft, since hydraulic control systems may be exposed to temperatures ranging from below — 65°F at high altitudes to over 100°F on the ground. For the proper operation of the hydraulic control system, the hydraulic fluid must have a sufficiently high VI to perform its functions at the extremes of the expected temperature range. 

In terminal areas, the air volumes are much greater, and typical HVAC filtration systems do not remove aerosol particles from the air as efficiently as do aircraft Environmental Control Systems (see Chapter 2). Thus, the costs and benefits of various enhanced filtration and air-cleaning strategies would have to be carefully assessed. An ancillary benefit to be considered would be the reduction of the transmission of common ills such as cold and flu viruses (or more serious viruses, such as the severe acute respiratory syndrome [SARS] virus) among airport patrons. 

When the pilot is trying to land the aircraft, this type of performance is undesirable. An overshoot of position may mean the plane misses the deck of the aircraft carrier. Also during landing it is not important to have lightning-fast response to joystick commands. Therefore the pilot switches the control system into the landing mode which has lower performance but is more robust. 

Phosphate esters have been produced commercially since the 1920s and now have important applications as plasticisers, lubricant additives and synthetic-based fluids for hydraulic and compressor oils. Their first use in lubrication was as anti-wear additives. Later developments in aircraft hydraulic control systems, particularly during the Second World War, introduced phosphate esters as less flammable hydraulic fluids. As esters of orthophosphoric acid they have the general formula OP(OR)3, where R represents an aryl or an alkyl group or, very often, a mixture of alkyl and/or aryl components. The physical and chemical properties of phosphate esters can be varied considerably depending on the choice of substituents [59, 60], selected to give optimum performance for a given application. Phosphate esters are particularly used in applications that benefit from their excellent fire-resistant properties, but compared to other base fluids they are fairly expensive. 

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