Pitot/Static System



Pitot Tube

– measures dynamic and static pressures and is positioned to be clear of the slipstream and facing the line of flight. THE AIRSPEED INDICATOR IS THE ONLY INSTRUMENT CONNECTED TO THE PITOT PRESSURE SOURCE.

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Pitot/Static System



Static Tube

– measures static pressure. The tube is vented to allow air pressure inside the instrument case to equalize with the outside air pressure. The vents are located on opposite sides so as to not be affected by turbulence.

ASI, ALTIMETER, VSI USE STATIC PRESSURE.

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Pitot/Static System

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Altimeter

 Measures the pressure in the atmosphere, which is the weight of the air above you at any given altitude. This weight will change as the aircraft climbs or descends causing the altimeter to register a change.

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Altimeter

 Regional Gliding School Made up of a stack of aneroid capsules each set at standard sea level. As the altitude changes these capsules expand and contract moving gears and thus the hands on the altimeter change.

Altimeter Errors

  Pressure: – the atmospheric pressure changes when flying from place to place. If not corrected the altimeter will be inaccurate.

Temperature: – the altimeter is constructed to work on the values of the ICAO standard atmosphere (15  C), the temp is not always at this value.

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Altimeter Errors

 Mountain Effect: – when flying near mountains, winds can be gusty and cause a drop in local pressure. Consequently, the altimeter will not give an accurate altitude indication.

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Airspeed Indicator

 Tells the pilot how fast they are traveling through the air and not over the ground and is measured in knots and miles per hour. Indicates the difference between pressures in the pitot and static tubes.

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Airspeed Indicator

 Regional Gliding School The reading on the airspeed indicator is referred to as the Indicated Airspeed (IAS). True airspeed (TAS) is the calibrated airspeed corrected for airspeed indicator error due to density and temperature.

Airspeed Indicator

 The instrument is made up of an aneroid capsule which measures the pitot pressure. The interior of the case is sealed and the static pressure is measured there. The changes in dynamic pressure (pitot) cause the aneroid capsule to expand and contract and this is registered and connected to a linkage that moves the hand on the ASI.

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Calibrated Airspeed

 Is indicated airspeed corrected for instrument errors and installation errors in the pitot static system Regional Gliding School

Equivalent Airspeed

 Calibrated airspeed corrected for compressibility factor.

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Airspeed Markings

Red Velocity never exceed (Vne) Yellow Caution (Vno) Green Normal (Vsl)

White

Flaps (Vfe)

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Airspeed Errors

   Density: – atmospheric density varies and as a result this will change the accuracy of the ASI.

Position: – Eddies that form as air passes over the wing are responsible for error.

Lag: – the slowness of the working parts are responsible for this error.

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Airspeed Errors

  Icing: – ice formation blocking either the pitot or static tube could give inaccurate readings.

Water: – water could block the tubes causing inaccurate readings.

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NOTE: You must use the buttons in the Confirmation Stage Regional Gliding School

Theory of Flight

Aircraft Instruments

Let's try a few review questions on Theory of Flight: Question #1 Which instrument is used to indicate height above sea level?

A

B

C

D

Altimeter Airspeed indicator Pitot indicator Static indicator

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Flying Scholarship Program I’m afraid that answer is

incorrect

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Flying Scholarship Program I’m afraid that answer is

incorrect

Let's try again...

Flying Scholarship Program I’m afraid that answer is

incorrect

Let's try again...

Flying Scholarship Program That answer is correct.

Let's move on...

Theory of Flight

Aircraft Instruments

Let's try a few review questions on Theory of Flight: Question #2 -

A

B

C

D

What is indicated airspeed corrected for instrument errors and installation errors in the pitot static system.

True airspeed Indicated airspeed Equivalent airspeed Calibrated airspeed

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Flying Scholarship Program I’m afraid that answer is

incorrect

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Flying Scholarship Program I’m afraid that answer is

incorrect

Let's try again...

Flying Scholarship Program I’m afraid that answer is

incorrect

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Flying Scholarship Program That answer is correct.

Let's move on...

Vertical Speed Indicator

 Indicates the rate of climb and descent and is measured in feet per minute.

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Vertical Speed Indicator

  Measures the change in pressure between the capsule (atmospheric pressure) and the case of the instrument. The capsule will expand and contract which is then transmitted by linkage to the dial of the instrument.

The instrument tends to lag and will only show an accurate rate after 6-9 seconds.

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Variometer

 A very sensitive rate of climb indicator that is used to find thermals. Works on the same principle as the altimeter: the higher the altitude the less the static pressure.

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

Magnetic Compass

Consists of two north seeking magnets which are attached to a float which is also attached to a compass card. This complete magnet system is mounted on a pivot and is free to rotate. The whole assembly is mounted within the compass bowl which is filled with alcohol to reduce the weight of the compass card and the magnets. The lubber line indicates the direction the aircraft is heading and is in line with or parallel to the longitudinal axis of the aircraft.

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Gyroscope

 It is a rotor, or spinning wheel, rotating at high speed in a universal mounting, called a gimbal, so its axle can be pointed in any direction.

 Gyroscopic Inertia: – the tendency of a rotating body to maintain its plane of motion.

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Gyroscope

 Precession: – the tendency of a rotating body, when a force is applied perpendicular to its plane of rotation, to turn in the direction of its rotation 90  to its axis and take up a new plane of rotation parallel to the force applied.

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Gyroscope

Gyro Instruments The Heading Indicator

 Regional Gliding School The heading indicator or directional gyro is an instrument designed to indicated the heading of the airplane and because it is steady and accurate, to enable the pilot to steer that heading with the least effort.

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Gyro Instruments The Artificial Horizon

The artificial horizon or attitude indicator provides the pilot with an artificial horizon as a means of reference when the natural horizon cannot be seen because of cloud, fog, rain or other obstructions to visibility. It shows the pilot the relationship between the wings and nose of the airplane and the horizon at the earth.

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

Gyro Instruments Turn and Slip Indicator

Needle indicates the direction and rate of turn.  Ball indicates slipping or skidding  If the ball is opposite to the needle in a turn you are skidding. With the ball and needle on the same side the turn is slipping.

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Gyro Instruments Turn and Slip Indicator

Straight and Level Coordinated left Turn Skidding Left Turn Regional Gliding School Slipping Left Turn

NOTE: You must use the buttons in the Confirmation Stage Regional Gliding School

Theory of Flight

Aircraft Instruments

Let's try a few review questions on Theory of Flight: Question #3 A rotor, or spinning wheel, rotating at high speed in a universal mounting, called a gimbal, so its axle can be pointed in any direction is known as

.

A

B

C

D

Variometer Magnetic compass Gyroscope Vertical speed indicator

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Flying Scholarship Program I’m afraid that answer is

incorrect

Let's try again...

Flying Scholarship Program I’m afraid that answer is

incorrect

Let's try again...

Flying Scholarship Program I’m afraid that answer is

incorrect

Let's try again...

Flying Scholarship Program That answer is correct.

Let's move on...

Theory of Flight

Aircraft instruments

Let's try a few review questions on Theory of Flight: Question #4 What instruments work on a gyroscope?

A

B

C

D

Variometer Artificial Horizon Magnetic compass Vertical speed indicator

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Flying Scholarship Program I’m afraid that answer is

incorrect

Let's try again...

Flying Scholarship Program I’m afraid that answer is

incorrect

Let's try again...

Flying Scholarship Program I’m afraid that answer is

incorrect

Let's try again...

Flying Scholarship Program That answer is correct.

Let's move on...

Theory of Flight

Aircraft Instruments

Congratulations!!

You have now completed the Aircraft Instruments lesson and the Theory of Flight Module. Of course, this lesson and module is always available to you for future reference if required.

You are now ready to move along to the next module you have not completed. You can advance to the Self Test Module if you feel ready to challenge the final exam.

Good Luck!

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