Chapter 4 Flight Instruments Flashcards
What are the 6 classes of instruments?
Pitot Tube, Magnetic, Gyroscopic, Electrical, Electronic, Self Contained
What are the two types of pitot tube instruments?
Static - Altimeter, Variometer
Dynamic - Airspeed Indicator, Total Energy Probe - separates ascent or descent due to pitch from thermal
Where is the static pitot tube mounted?
Usually on the sides of the fuselage.
Where is the dynamic tube located?
Usually it extends out from the vertical stabilizer.
How does the airspeed indicator work?
It measures the difference between the total pressure and the static pressure to find the dynamic pressure which represents the airspeed.
What are the three types of airspeed?
Indicated IAS, Calibrated CAS , True TAS, Ground speed GS
What is Calibrated Airspeed CAS?
CAS is indicated IAS adjusted for position sensing errors and instrument errors. It is a calculated value.
What is True Airspeed TAS?
TAS is IAS corrected for pressure and temperature. It is a calculated value. True airspeed is always higher than indicated airspeed. TAS increases 2% above IAS for each 1000’ increase in altitude. TAS at 10,000’ will be 20% higher than IAS.
IAS values does not change with altitude for what designated speeds?
Stall speed, Min Sink speed, Best L/D speed.
What happens to Vne as altitude increases?
Vne decreases as IAS as altitude increases. Vne would be constant for TAS.
What is maneuvering speed?
Max speed where full movement of one flight control can safely be used. Also max speed in rough air. Sometimes marked at the top of the green arc.
What arc on the airspeed indicator is used for flap deployment?
White arc
What does green arc represent?
Normal operating range.
What does yellow arc represent?
Safe operating range in smooth air.
What does red line mean?
Vne
What does the triangle on the airspeed indicator mean?
Recommended approach speed.
Regardless of altitude, Indicated airspeed is the same for what?
Stalls. Stall speed does not change.
Biggest difference between IAS and CAS occurs when?
High AOA, Yawing, Low speed, flap/spoiler deployment.
Other airspeeds to know.
Landing gear, tow speed
How does the altimeter work?
A sealed chamber expands or contracts based on the static pressure acting on the outside of it. The chamber is attached to the needle of the altimeter and moves the needle when it contracts or expands.
How should the altimeter be set?
The local barometric pressure (adjusted to sea level) should be set in the Kolsman window.
What rate does the barometric pressure change with altitude?
1” Hg or .5 psi per 1000’.
The altitude read on the altimeter is referred to as what?
Indicated altitude in MSL.
What is MSL?
Altitude above mean sea level.
What is AGL?
Absolute Altitude. Altitude above the terrain
What is TAS?
Indicated airspeed IAS adjusted for temp and pressure
Define Pressure Altitude.
Pressure altitude is MSL altitude when Kolsman window is set for std pressure of 29.92”. Used to calculate Density Altitude.
What is Density Altitude?
Pressure Altitude adjusted for actual temperature. It is used to determine performance of plane. High density altitude compromises performance.
Density altitude increases as temperature increases/decreases?
Increases.
What is a variometer used for?
Measures rate of ascent or decent. Climb or sink.
How does a variometer work?
It measures the rate of change in static pressures to determine the rate of climb or sink. If P new > P old = sink. They do not take into account the airspeed change or sink rate.
What is a dis-advantge of a non electric variometer?
Slow response and no audible tone for climb or sink.
What does a Total Energy variometer measure?
It is a variometer that compensates for a change in speed. If speed increases, it views that as a sink and nulls that out of the calculation. If speed decreases, it views that as a climb and nulls that out of the calculation.
How is a Netto different from a TE variometer?
It compensates the TE reading for the sink rate of the glider. So it is measuring the airmass lift or sink.
What functions do flight computers have?
GPS - where you are. where you’ve been, distance to destination, time to get there, speed to fly to get there,
What is a space defined by latitude, longitude, and altitude?
Waypoint
What is a turnpoint?
A waypoint on a race course.
What is the benefit of ballast?
The sink rate increases but so does the speed. So the glide ratio stays the same. You get to your destination faster.
What is the difference between True North and Magnetic North?
True North is geographic. The difference is called magnetic variation. Magnetic deviation is caused by electrical equipment in the plane and varies for different headings.
What is an Inclinometer?
Indicates co-ordinated flight. Similar to the yaw string. Affected by centrifugal force and gravity. “Step on the ball”.
The yaw string deflected to the outside of a turn indicates slipping or skidding?
Slipping
Name 3 Gyroscopic instruments
Attitude indicator, Heading indicator, and Turn indicator. Rarely found in gliders.
Which type of G-force pushes you down into your seat?
Positive. Negative = weightlessness.
What does a FLARM do?
Detects and locates other gliders equipped with a FLARM. It has a short range so it is not useful for detecting fast moving planes.
What is OAT?
Outside air temperature. Good for determining if ballast could freeze.
What is the difference between the magnetic deviation and variation?
Magnetic deviation is the error due to devious electrical waves from instruments.
Magnetic variation is the difference between magnetic north and geographic north.
How is magnetic variation compensated.
The sectional map will show magnetic variation lines and values such as 8 degrees west. If west, add the value to your geographic heading to get your magnetic heading. If east, subtract the value from your geographic heading to get your magnetic heading. East is least (subtract) West is best (add).
How does acceleration and deceleration affect compass readings?
Does not affect readings on a pure north or south heading. An acceleration will move the needle to the north. AN A deceleration will move the needle to the south, DS ANDS This is true in the Northern Hemisphere. Opposite in the Southern hemisphere.
How is the compass affected by turning error.
On a northern heading, a turn to the east or west will cause the compass to lag the actual heading.
On a southerly heading, a turn to the east or west will cause the compass to lead the actual heading.
LAN LES Lag North Lead South
When a left hand turn is made, the compass will move to the left/right?
Right
CCW turn = CW compass rotation
Compass is stationary - plane moves around it
Decreasing the pressure setting in the Kolsman window will Increase/decrease the indicated altitude?
Indicated altitude will decrease.1000’ = 1” Hg
