While flying a plane without any electronics would be appealing to the Wright Brothers, the commercialization of air travel has seen to higher standards in safety and navigation. Since planes still tend to crash, it's safe to assume that at least the aviation engineers got the navigation part right!
Instruments are used by pilots to maneuver the plane and navigate precisely, while maximizing performance and safety.
Of these various instruments, 6 shown below prove to be an invaluable asset to aerial navigation.
In early 1930s, the arrangement of these specialized instruments on a panel mounted independently of the remainder is a custom which comes to us from the United States.
These Flight instruments can be divided into two basic categories based on their working:
The Pitot-Static system is comprised of pitot tubes and static ports that are usually located on either side of the forward fuselage, underneath the pilots’ windows. The pitot tubes are mounted parallel to the longitudinal axis of the aircraft and generally in line with the relative wind.
There are always several pitot tubes and static ports so that the pressure readings can be averaged out and also to ensure that there are backup and alternate sources.
The airspeed indicator is connected to the Pitot Static System. To give a reading of speed through the air, the flight instrument measures the difference between the dynamic pressure in the Pitot Tube and the atmospheric pressure from the Static vent.
When the airplane is standing still on the ground, the pressure in the two systems will be the same resulting in a reading of zero. However, when the airplane is travelling through the air, the dynamic pressure in the Pitot system will increase and a reading is registered.
The pilot relies on both the Altimeter and the Vertical Speed Indicator to monitor altitude and altitude changes. At a glance, the VSI shows the pilot if they are flying at a steady altitude, or if they are ascending or descending, and the rate at which their altitude is changing in feet per minute.
A Gyroscope is a rotor or spinning wheel, rotating at a high speed. Usually, this is powered by the Vacuum System Pump. Gyroscopic Inertia is the tendency of a rotating body to maintain its plane of rotation, known as Rigidity in Space. Gyroscopic Precision is the tendency of a rotating body to consistently react to a force being applied by turning in the direction of its rotation exactly 90 degrees to its axis. These principles of physics are used to make very precise Flight Instruments:
Instruments are used by pilots to maneuver the plane and navigate precisely, while maximizing performance and safety.
Of these various instruments, 6 shown below prove to be an invaluable asset to aerial navigation.
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| six flight instruments; basic-T, basic flight instruments (Photo credit: Wikipedia) |
These Flight instruments can be divided into two basic categories based on their working:
Pitot-Static Instruments:
This group of instruments comprises of three instruments mentioned below in detail. The reason they are classified as Pitot-Static is due to the fact that all these instruments rely on readings taken solely from the air pressure surrounding the aeroplane.The Pitot-Static system is comprised of pitot tubes and static ports that are usually located on either side of the forward fuselage, underneath the pilots’ windows. The pitot tubes are mounted parallel to the longitudinal axis of the aircraft and generally in line with the relative wind.
There are always several pitot tubes and static ports so that the pressure readings can be averaged out and also to ensure that there are backup and alternate sources.
- Air Speed Indicator
The Airspeed Indicator measures the speed of the aircraft through the air, this is the speed at which the air is flowing over the airplane. The dial is usually calibrated in Nautical miles known as Knots.
When the airplane is standing still on the ground, the pressure in the two systems will be the same resulting in a reading of zero. However, when the airplane is travelling through the air, the dynamic pressure in the Pitot system will increase and a reading is registered.
The Indicated airspeed (IAS) is the reading displayed on the face of the instrument. The small windows at the top and bottom of the Airspeed Indicator are used for determining True Airspeed (TAS). Remember, the Airspeed Indicator displays the Indicated Air Speed (IAS), and adjustments are needed to calculate the Calibrated Airspeed (CAS) and True Airspeed (TAS).
- Altimeter
The Altimeter measures the Altitude or height of the aircraft above Sea Level. Remember, ground elevation varies widely, so the Altimeter reading does not measure height about the Ground, but instead above Sea Level. The Pilot must be aware of the Ground elevation, to then calculate the height of the airplane above the Ground.
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| English: Schematic of a drum-type altimeter (Photo credit: Wikipedia) |
The Altimeter reading is based on barometric pressure, and barometric pressure is constantly changing. This requires the altimeter to be set prior to every flight, and during flight as barometric pressure in your flying area changes.
- Vertical Speed Inidcator
The pilot relies on both the Altimeter and the Vertical Speed Indicator to monitor altitude and altitude changes. At a glance, the VSI shows the pilot if they are flying at a steady altitude, or if they are ascending or descending, and the rate at which their altitude is changing in feet per minute.
Gyroscopic Instruments:
A Gyroscope is a rotor or spinning wheel, rotating at a high speed. Usually, this is powered by the Vacuum System Pump. Gyroscopic Inertia is the tendency of a rotating body to maintain its plane of rotation, known as Rigidity in Space. Gyroscopic Precision is the tendency of a rotating body to consistently react to a force being applied by turning in the direction of its rotation exactly 90 degrees to its axis. These principles of physics are used to make very precise Flight Instruments:
- Attitude Indicator
The Attitude Indicator uses a Gyroscope to stabilize a horizon bar which stays parallel to the natural horizon. The miniature airplane in the center of the Attitude Indicator will pitch and bank around the horizon bar to indicate the airplanes current attitude relative to the horizon.
- Heading Indicator
The Heading Indicator is gyroscopically stabilized. Unlike the magnetic compass, the Directional Gyro is not as affected by banks, turns, and speed changes. However, the Heading Indicator is NOT a magnetic compass.
The outline of an aircraft is positioned over a 360 degree scale with markings for North, East, South and West. The larger markings indicate 10 degrees each, and the smaller markings denote 5 degree variations.
The outline of an aircraft is positioned over a 360 degree scale with markings for North, East, South and West. The larger markings indicate 10 degrees each, and the smaller markings denote 5 degree variations.
- Turn Coordinator
This instrument gives information about the direction and rate of a turn. Additionally, it indicates if the turn is being flown in coordinated flight. If the aircraft is slipping or skidding during a turn, the ball (inclinometer) in the bottom portion of the Turn Coordinator will not be centered.
During a coordinated turn, the ball will remain centered. If the ball is not centered, the pilot must adjust the turn by using more or less rudder to correct for adverse yaw.
