RMIT飞行训练课件－ RMIT飞行训练课件－Pitot Static System 皮托静压系统
**** Hidden Message ***** PITOT / STATIC SYSTEMS<BR>Aim: To understand the principles of operation behind a pitot / static system,<BR>considering the possible errors and limitations involved.<BR>Application:<BR>- Used when relying on the pressure instruments.<BR>- ASI, ALT and VSI.<BR>Revision:<BR> Static Pressure<BR>- pressure due to weight of air molecules pushing down. Reduces with<BR>increased altitude.<BR> Dynamic Pressure<BR>- pressure due to relative movement. Depends on density and velocity.<BR>- PD =<BR> Total Pressure<BR>- PT =<BR>Definitions:<BR> Static Vent<BR>- measures PS and usually flush-mounted on fuselage side.<BR>Brief 28<BR>RMIT Flight Training Pitot/ Static Systems<BR> Pitot Tube<BR>- measures PT and mounted where airflow not greatly disturbed. Usually on<BR>outer wing section.<BR>- pitot heat provided to guard against ice.<BR> Alternate Static Source<BR>- emergency static port, found in cockpit, used in an emergency.<BR>- slightly lower than atmosphere pressure due to slight suction created by<BR>door seals.<BR>Principles:<BR> A typical pitot/ static system is shown below:<BR> Airspeed Indicator (ASI)<BR>- measures PD (½V2) and extracts V to show aircraft velocity.<BR>- diaphragm is used filled with pitot pressure (PT) and PS surrounding it. The<BR>diaphragm will position itself, and the pointer will then relate the difference.<BR>PD = PT – PS<BR>Brief 28<BR>RMIT Flight Training Pitot/ Static Systems<BR> Altimeter (ALT)<BR>- uses PS only and relates it to height<BR>- contains an aneroid capsule exposed to PS from the static vent. Fixed<BR>diaphragm contains air as a reference. As aircraft climbs, PS reduces and<BR>the capsule expands driving the pointer via mechanical linkages.<BR>- time lag does exist<BR> Vertical Speed Indicator (VSI)<BR>- uses PS only, and works on the principles of converting rate of change of<BR>PS to a rate of change of altitude<BR>- instrument is a flexible capsule exposed to PS housing a choke valve.<BR>- aircraft descends, PS increases. This pressure is fed into the capsule and<BR>the choke valve. Therefore there is a delay to the increase in PS in the<BR>capsule. The capsule then expands driving a pointer until the pressure<BR>equalises with that in the choke valve.<BR>Considerations:<BR> Instrument Errors<BR>- due to imperfections in the design and installation.<BR> Instrument Lag<BR>- response time of pressure instruments can be slow due to long lines or<BR>rapid pressure changes.<BR> Position Error<BR>- poor design and placement of vents may not be representative of the free<BR>atmospheric pressure.<BR>Brief 28<BR>RMIT Flight Training Pitot/ Static Systems<BR> Blockages<BR>ASI ALT VSI<BR>Pitot Climb Over read - -<BR>Blockage Descent Under read - -<BR>Static Climb Under read Under read Under read<BR>Blockage Descent Over read Over read Over read<BR>Airmanship:<BR>- Know where the alternate static source is located<BR>- Always check pitot and static vents during pre-flight<BR>Brief 28<BR>RMIT Flight Training Pitot/ Static Systems<BR>Brief 28<BR>RMIT Flight Training Pitot/ Static Systems<BR> 感谢楼主万分感谢感谢万分 谢谢楼主，我正准备去RMIT读书
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