Aircraft System Principles and Applications - Assignment Example

Aircraft System Principles and Applications Question 1 Determine the properties of air as a fluid power medium for aircraft systems Properties of air play a vital role during the flight of an aircraft. It directly affects the aerodynamic properties of the aircraft system. Most common properties of air that directly influence the flight of an aircraft are temperature, pressure, density and humidity(Attwooll, 2010, McClamroch, 2011), and how do they affect a flight, is discussed below: Properties of air and their correlation: Air pressure and air temperature are directly associated with each other. Before going into the details of how air properties affect the flight of a plane, one must have deep insight into the correlation of air properties. Variation in air pressure directly affects the density of air if the temperature is kept constant. Both the pressure and the density are directly proportional to each other and if pressure decreases at a given temperature, density of air also decreases resulting in greater distance between air molecules. If another case is considered, in which pressure is kept constant, increased temperature results in decreased density of air and decreased temperature results in increased density, and hence keeping the molecules closer. These relationships among density, temperature and pressure govern the overall performance of the aircraft while being in flight. Effect of air density on aircraft performance Air density is responsible for lifting the aircraft at the start of flight. It is also responsible for favorable amount of fuel consumption as air density affects air fuel mixture which is burned to run the engine. Therefore, fuel consumption and lift of aircraft not only depends on density but also depends upon temperature and pressure, indirectly. Effect of air pressure on aircraft performance An aircraft requires maintaining a specific pressure to keep flying in the air or to move to higher altitudes. As the lift of aircraft is directly affected by the density of air, so in order to move to higher altitudes density of aircraft must be greater than 1225 gm/m-cube. Reduction in density results in lesser amount of air molecules moving around the plane and hence, lesser amount of thrust is applied on the plane than is required to move at higher altitude(FAA). Effect of air pressure on aircraft performance Air may have parcels of air that are having raised temperatures and this raised temperature significantly reduces density of air within these parcels. Whenever a plane enters from a parcel of lower temperature to a parcel of higher temperature, it undergoes variation in performance. Due to lower density, flight of plane is adversely affected and it also affects the fuel efficiency of the engine due to insufficient air required to inject fuel. Therefore, planes are equipped with turbochargers in order to maintain air pressure. Question 2 Explain the function and operation of aircraft pneumatic systems and their associated status indicators? Old aircraft systems were based on high pressure pneumatic systems which make use of air as a power transmission medium. Most common components that make use of pneumatic system are: Brakes Closing and opening of doors Operation of emergency devices, for example landing gears, flaps etc. Driving of hydraulic and water pumps etc. Pneumatic power systems are most commonly named as vacuum pressure systems, where pressure is measured by making use of suction pressure. Vacuum pressure system facilitates following components named, pumps, relief valves, vacuum air filter, suction gauge gyro instruments(FAA). Before the air enters the pneumatic system, it is passed through the air filter in order to filter out impurities and dust particles. These particles, if enter the pneumatic system, damage the system adversely. After that it is served to the pumps which are used to pump out air at desired pressure required by the pneumatic system. It is considered the most important part of the system without which system would not work. The pumped air is then directed to the required locations by making use of pressure regulating valves which are also fundamental part of the pneumatic system and help in building as well as releasing excess pressure when required. These valves also help in directing the flow of air within the system(Bremmer, 2006). This is a typical pneumatic system used in aircrafts. Filtered, pumped air is passed through gyro which makes it to spin. This spinning action then results in providing rigidity to the plane during flight. It also helps in the exhaust of excess air through gyro pressure gauge(G.H.Balding, 1967). This suction guage also informs the pilot for upcoming danger and gives timely warning in case of any malfunctioning in the pneumatic system. Other indicators that are run by pneumatic systems are heading indicator and altitude indicator which majorly work on the basis of calculating air pressure of the incoming air. Question 3 Investigate the function, nature and operation of aircraft pressurization, air conditioning and refrigeration systems and their associated indication system? Aircrafts fly at high altitudes as it is fuel efficient as well as helps in avoiding changing weather conditions like storm, rain, clouds etc. In order to fly at such greater heights, proper air pressure is needed to be maintained within the aircraft. Atypical aircraft system consists of cabin, baggage section and flight compartment within the pressurization system in which pressure is kept much high as compared to the outside pressure(Larson, 2002). In some of the aircraft designs, where turbines are being used to power the aircrafts, bleed air is used for pressurizing the cabin. In other models superchargers are used to pump air to the sealed cabin and compartment assembly in order to maintain the pressure. The sealed chamber is also provided by valves in order to provide air vent if necessary. Below is the image of a typical pressurized aircraft compartments. Pilot is provided with pressurization gauges within his cabin from where he can get the idea if the sealed chamber is properly pressurized or not. Other gauges available are differential pressure gauge, ambient pressure gauge and ambient temperature gauge. This is a schematic diagram of a typical air conditioning and refrigeration system. The air before being provided to the fuselage is passed through an air-conditioning system(Casey, 2000). Air is conditioned to maintain proper pressure within the compartments and also plays significant role in keeping proper temperature within the crew and pilot cabin, and passenger side compartment. Question 4 Explain the operation and constructional features of pneumatic systems components? Main components of a typical pneumatic system are listed below: Compressor Filter Pump Piping Valves Actuation Unit The pneumatic systems work by making use of air as a fuel medium. In aircraft pneumatic systems air is taken from the environment and firstly it is compressed and filtered. Purpose of compressing the air is to pressurize it to a required level so that high pressure within the fuselage can be maintained at high altitudes in order to improve the flight of the aircraft. But the air that is compressed must be passed through an air filter in order to remove all the impurities, dust particles, and humidity content that may harm the internal structure of the fuselage and other components directly in contact with air. The compressed air is then pumped at desired pressures to the subsequent compartments of the pneumatic system which is most commonly a pump. Various check valves and directional valves are used before and after pump, in the pneumatic piping, to maintain flow direction and provide air vent if pressure exceeds the required level. Pneumatic piping then transmits the pumped air to the required components and air bleed ports(Thomas, 2005). From there, compressed air is distributed to fuel injection system for the combustion of fuel and also to the fuselage in order to maintain pressure and air quality within the cabins and compartments. Question 5 Explain the operation and constructional features of components used in aircraft pressurization, cabin conditioning and refrigeration systems? The operational and constructional features of aircraft pressurization and air conditioning components are much similar to the pneumatic system components. The incoming air is first compressed to a high density air. This bleed air (hot air from compressor) is then transferred to air conditioning and pressurization system of the aircraft through ducts. The pipeline that transfers air to these systems are provided with a set of flow control valves which are responsible for maintaining air pressure as well as keeping the flow direction constant. When the compressed air is provided to the air pressurization system, it helps in maintaining high pressure, whereas, in case of air conditioning systems two air exchangers are provided(Kull, 1994). These air to air exchangers help in exchanging the fresh warm air from outside to the inside of the passenger compartment and crew and inside air is exited through an air duct system. The cold exited air is then reconditioned with fresh warm air to achieve required temperature and the cycle keeps on working. All these external components are packed within the pack controller to protect the system and keep it functioning well. References ATTWOOLL, V. W. 2010. Aircraft Characteristics and Air Traffic Systems. Journal of Navigation, 27. BREMMER, R. 2006. Pneumatic Systems. Air Saftey Foundation, SB06-06/06. CASEY 2000. Aircraft air conditioning system and method. US patent. FAA Hydraulic and Pneumatic Power Systems. Handbook of Regulation Policies. FAA Principles of Flight. Handbook of Regulation Policies. G.H.BALDING 1967. Electronic visual cue indicator system for aircraft. US patent. KULL, H. 1994. Refrigeration System for an Aircraft. US Patent. LARSON, G. C. 2002. How Things Work: Cabin Pressure. Air and Space. MCCLAMROCH, N. H. 2011. Fluid Mechanics and Aerodynamics. Steady Aircraft Flight and Performance. THOMAS, M. I. 2005. Cabin Air Conditioning System with liquid cooling for power electronics. US Patent. Read More