The airspeed indicator or airspeed gauge is the instrument used in the aircraft to display the speed of the plane, usually in knots, for the pilot. In its simplest form, ASI measures the pressure difference between the air around the plane and the increased pressure caused by the propulsion. The needle tracks the pressure difference but the dial is marked as the airspeed.
Video Airspeed indicator
Use
The air velocity indicator (ASI) is used by the pilot during all flight phases, from take-off, climbing, sailing, descending and landing to maintain specific airspeed for the aircraft type and operating conditions as specified in the Operations Manual.
During an instrument flight, the airspeed indicator is used in addition to the attitude indicator (artificial horizon) as the reference instrument for pitch control during climb, down and spin.
Air speed indicator is also used in dead calculations, where time, speed, and bearing are used for navigation in the absence of tools such as NDB, VOR, or GPS.
On a light plane
Air speed indicators in many Light and Recreational aircraft can only show Airspeed Pilots (IAS). For True Airspeed (TAS), other components must be added by the manufacturer. The Airspeed Indicator mark uses a set of bands and standard colored lines on the face of the instrument. White distance is the normal range of operating speed for aircraft with extended flaps such as for landing or take-off. The green range is the normal range of operating speed for aircraft without extended flaps. The yellow range is the range in which the plane can be operated in fine air, and then only with caution to avoid sudden control movements.
The red line indicates V NE , or speed (never exceeds) . This is the maximum air velocity indicated by the plane which the aircraft must not exceed under any circumstances. The red line is preceded by a yellow ribbon which is a warning area, running from V NO ( maximum structural cruising speed ) to V NE . The green band runs from V S1 to V NO . V S1 is the kiosk velocity with flap and landing gear drawn. The white ribbon runs from V SO to V FE . V SO is the speed of the stall with extended flaps, and V FE is the highest speed at which flaps can be extended. The air velocity indicator in a multi-engine aircraft shows a short radial red line close to the bottom of the green arc for V mc , the minimum indicated air velocity in which the aircraft can be controlled by a critical engine not operating and blue line for V YSE , speed for best climbing rate with critical machine not operating.
On a large plane
Air speed indicator is very important to monitor V-Speed ​​when operating an airplane. However, in large aircraft, the V speed may vary depending on the height of the airfield, the temperature and the weight of the aircraft. For this reason the colored ranges found on breast milk from light aircraft are not being used - instead the instrument has a number of moving pointers known as bugs which may be arranged by the pilot to show the V-velocity appropriate for the current conditions.
The jet plane does not have V NO and V NE like a piston engined aircraft but has a maximum IAS operation, V MO and maximum Mach number, M MO . To observe these two limits, jet pilots need both airspeed and Machmeter indicators, each with a corresponding red line. In some common aviation jets, Machmeter is incorporated into a single instrument containing a pair of concentric indicators, one for the air velocity shown and the other for the indicated Mach number.
A single alternative instrument is "the maximum allowable airspeed indicator." It has a moving pointer that shows the maximum operating limit (Vmo or Mmo). The pointer moves with altitude and temperature so it always shows the maximum allowable speed of the aircraft. The pointer is usually a red-and-white stripe, and is thus known as a "barber pole". As the plane rises to high altitude, so that M MO instead of V MO becomes a limiting speed, the barbers pole to a lower IAS value.
Modern aircraft use a cockpit glass instrument system using two airspeed indicators: an electronic indicator on the primary flight data panels and traditional mechanical instruments for use if the electronic panel fails. Air velocity is usually presented in the form of "ribbon strips" that move up and down, with the current air velocity in the middle. The same color scheme is used as in the mechanical air velocity indicator to represent velocity V.
Maps Airspeed indicator
Operation
Along with altimeter and vertical speed indicator, air speed indicator is a member of pitot-static system of flight instrument, so named because they operate by measuring pressure in pitot and static circuit.
The air speed indicator works by measuring the difference between static pressure, captured through one or more static ports; and the pressure of stagnation due to "air ram", is captured through a pitot tube. The difference in pressure due to the air ram is called impact pressure.
The static port is located on the exterior of the aircraft, in the location chosen to detect the atmospheric pressure as accurate as possible, that is, with minimum interference from the presence of the aircraft. Some aircraft have static ports on either side of the plane or empennage, in order to more accurately measure static pressure during slip and down. Aerodynamic slippage and skid causes one or both static ports and pitot tubes (s) to present themselves to relative winds other than basic forward movement. Thus, alternative placement on multiple planes.
Icing is a problem for pitot tubes when temperatures below freezing and visible moisture are present in the atmosphere, such as when flying through clouds or rainfall. Electrically heated pitot tubes are used to prevent ice formation on top of the tube.
Air velocity and altimeter indicators will be made non-operative by plugging in static systems. To avoid this problem, most aircraft intended for use in instrument meteorological conditions are equipped with an alternative source of static pressure. In a plane without pressure, an alternative static source is usually achieved by opening a static pressure system into the air in the cab. This is less accurate, but it is still workable. In a pressurized plane, an alternative static source is a second set of static ports on the skin of the plane, but in a different location to the primary source.
Variations
The Lift Reserve Indicator (LRI) has been proposed as an alternative or reserve to the Airspeed Indicator (ASI) during the critical phase of flight. It is an elegant device, but rarely found in light aircraft or even hauling jets. The conventional air velocity indicator is less sensitive and less accurate because of reduced airspeed, thus providing less reliable information to the pilot when the plane slows down to the store. The actual kiosk velocity of the aircraft also varies with flight conditions, particularly changes in gross weight and wing loading during maneuvers. Breast milk does not show directly how the kiosk is approached during these maneuvers, while LRI does it.
LRI shows the pilot direct Potential Wing Lift (POWL) above the kiosk at any time and at airspeed, so it's more descriptive and easier for the pilot to use. LRI uses dynamic differential pressure and Angle of Attack to operate. This is a very fast and very accurate acting at low airspeed, thus providing more reliable information to the pilot when airspeed is reduced and becomes critical.
LRI uses a three-zone, red-white-green screen. During the flight, the green zone is way above the stall where the flight control is strong, the low attack angle, and the high unused POWL. The white zone is near a kiosk where flight controls soften, high attack angles, and unused POWLs are reduced. The top of the red zone defines the start of the booth. Severity of the kiosk increases as the needle moves deeper into the red. During takeoff, the LRI uses dynamic pressure to operate and will not raise the needle above the red zone until sufficient air velocity energy is available for flight.
The pilot adjusts the instrument to show the edges of the red-and-white zone during a minimum airspeed exercise at altitude, indicating the plane has a POWL zero outside that point. Since the wing will stop at the same angle of attack at any air velocity, after adjusting properly, the LRI will show the red-and-white edges whenever the store is approached. These include landing stalls, climbing stalls, and accelerated stalls. After adjustment, the black line in the center of white indicates maximum angle of climb and maximum tilt angle with sufficient reserve reserve for the landing flare. With practice, pilots can use the LRI to determine the exact time to take off with minimum ground roll and maximum climbing combination.
LRI has been well received by STOL (short take off and landing) pilots and pilots experimental or home-made aircraft. LRI is particularly useful for short field landings, short field takeoffs, and low speed maneuvers such as steep, steep inclines, and steep inclines, and also allows fast or "slippery" pilots to land with little or no reliable buoys.. Since LRI is particularly useful at the critical downstream of the flight envelope, most pilots will use LRI as a complement to breastmilk, using LRI for slow speed work and breastmilk for roaming and navigational work.
Type of airspeed measurement
Bantuan memori: " ICE-T " ( es teh ), atau I ndicated- & gt; C alibrasi- & gt; E quivalent- & gt; T rue.
Other memory tools: This is a P retty C ool D , giving a compensated error between the speed P osition/ P ressure, C compression, and D ensity.
At increasing altitude (more accurately, density heights), for the same shown air velocity (IAS), actual airplane airspeed (TAS) will be higher, but the same airspace limit applies. Likewise, the most efficient cruise speeds, total drag, available lift, kiosk speed, and other aerodynamic information depend on calibrated airspeed, not true. Most aircraft show a small difference between the actual air velocity shown on the instrument (indicating airspeed, or IAS) and the instrument speed should theoretically show (calibrated airspeed or CAS). This difference, called position error, is mainly due to inaccurate static pressure. It is usually not possible to find a position for a static port that, at all angles of attack, accurately senses atmospheric pressure at the altitude at which the aircraft is flying.
The Bernoulli principle states that total pressure is constant throughout the current. The pitot pressure is equal to the total pressure so that the pitot pressure is constant around the plane and does not experience a fault position. (However, the pitot pressure may experience an alignment error if the pitot tube is not aligned directly to the approaching airflow.)
The position of the static port should be chosen carefully by the designer of the aircraft because the position error must be small at all speeds within the operating range of the aircraft. Special calibration graphs for aircraft types are usually provided.
At high speed and altitude, calibrated airspeed should be corrected further for compressibility errors to provide equivalent airspeed (EAS). Compressibility errors arise because impact pressure will cause compressed air in the pitot tube. The calibration equation (see calibrated air velocity) contributes to the compressibility, but only to standard sea level pressures. At other altitudes correction of compressibility errors can be obtained from the graph. In practice the compressibility error is ignored under about 3,000 m/10,000 feet and 100 m/s/200 knots CAS.
Actual air velocity can be calculated as a function of equal air velocity and local air density, (or temperature and pressure levels that determine density). Some airspeed indicators incorporate slide rule mechanisms to perform this calculation. If not, it can be done with a calculator like the E6B circular slide rule. For a quick estimate of TAS add 2% per 300m/1000 feet height to IAS (or CAS). eg IAS = 52 m/s/100 Knot. At an altitude of 3000 m/10,000 'above sea level, the TAS is 62 m/s/120 knots.
See also
References
Source
- Aircraft Fly Handbook . US Government Printing Office, Washington D.C.: U.S. Federal Aviation Administration. 2004. FAA-8083-3A. Archived from the original on 2011-06-30.
- Flying Instrument Handbook (PDF) . US Government Printing Office, Washington D.C.: U.S. Federal Aviation Administration. 2005-11-25. FAA-H-8083-15. Ã,
- The Aeronautical Knowledge Pilot Handbook . US Government Printing Office, Washington D.C.: U.S. Federal Aviation Administration. 2003. FAA AC 61-23C. Archived from the original in 2015-07-01.
Install and fly Lift Reserve Indicators, articles and photos by Sam Buchanan http://home.hiwaay.net/~sbuc/journal/liftreserve.htm
This article incorporates public domain material from a US Government document "Airplane Flying Handbook".
This article incorporates public domain material from a United States Government document "Instrument Flying Handbook".
This article incorporates the public domain material from the documents of the United States Government "Pilot's Handbook of Aeronautical Knowledge".
Source of the article : Wikipedia
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