What is the pitot static system?
The pitot static system uses air pressure from the pitot tube and the static port to operate the altimeter, vertical speed indicator, and airspeed indicator.
What does the static port measure?
It measures air pressure of the surrounding atmosphere without the effects of forward motion.
It is pure undisturbed ambient air pressure known as static pressure
Which instruments require the static port?
Altimeter , Vertical Speed Indicator, Airspeed indicator.
What is atmospheric pressure?
The atmospheric pressure at any point due to the weight of the overlying air above, which decreases as the height above sea level increases.
What is the pitot tube system, and how does it work?
The pitot tube system measure forward ram air pressure created by the plane moving forward through the air.
The pitot tube system sends this pressure reading to the airspeed indicator and compares it to the static pressure from the static port by subtracting both and giving the resulting difference as Indicated Airspeed.
The altimeter is part of the pitot tube system.
No bitch,
The airspeed indicator is the only instrument part of the pitot tube system.
How does the altimeter give you altitude?
The altimeter detects outside sea level pressure and compares it to a vaccum inside. The aneroid inside expands or compressing as air enters or moves out of the case via the static system as pressure changes. Giving you altimeter reading.
What is pressure altitude?
Altitude indicated when altimeter is set to 29.92.
What is standard air conditions?
15°C, at 29.92 inHg, at 0 feet [sea level]
Give altimeter errors.
Pressure Error- changes in atmospheric pressure will cause the altimeter to overread/underread
Ex, flying from an area of high pressure to low pressure altimeter will overread- you are lower than indicated. Opposite applies as well. Altimeter will underead, higher than what you are.
Temperature error- when temperature differs from standard. When temperature is colder than standard conditions true altitude is lower than indicated.
When temperature is hotter than standard conditions, true altitude is higher than indicated.
What is Density Altitude? What does it assume?
Pressure altitude corrected for non standard temperature, used for aircraft performance such as loads,fuel, payload and take off distance.
It assumes standard air temperature is 15°C, the standard air temperature drops 2°C/1000ft and every degree of difference from standard air there is a 100 foot difference in pressure altitude.
What is true altitude?
Height above sea level.
What is absolute altitude?
The actual height above the earth’s surface.
What is the equation for Density Altitude?
Density Altitude = Pressure Altitude +[100(actual temperature-standard temperature)
What is the vertical speed indicator , what system does it use and how does it give you a reading?
The vertical speed indicator shows the rate of ascent or decent in feet per minute.
Uses the static pressure system operates with the change of barometric pressure as height changes.
Now more throughly, how does the vertical speed indicator give you a reading?
Air enters from the static pressure system into the capsule, at the same time air leaks from the capsule at a controlled slow rate which allows the pressure within the capsule to be equalized and causes the aneroid to contract or expand.
In a descent, how does the vertical speed indicator work.
Pressure into the capsule increases, while as pressure inside the case is leaked slowly and decreases. Causing the aneroid to expand.
What is an error of the vertical speed indicator?
There is a lag before the vertical speed indicator shows the correct rate of ascent/descent, or even as you level off. Abrupt changes will demonstrate the lag more.
What is the airspeed indicator? How does it give a reading of speed ?
Gives speed aircraft is traveling through the air, either in knots or miles per hour.
Ir measures the difference between the pitot system pressure and static pressure system.
What are the different airspeeds?
Indicated- the speed shown by the indicator
Calibrated - corrected for instrument and installation error .
Equivalent - corrected for compressibility factor.
True - corrected for density and pressure.
What is position error?
It is an airspeed indicator error, occurs when the pitot tube and static port is receiving inaccurate airflow during high angles of attack, slips/skids, turbulence, or configuration changes.
What are some airspeed indicator errors, besides position error and icing/blockages?
A) Density Error - The tendency of the airspeed indicator to over/underread as result of changes in altitude and atmospheric pressure changes.
B) Compressibility Error - Air compresses in pitot tube at high speeds, makes ASI overread.
C) Lag - Mechanical friction causes the airspeed indicator to have a delay moving the needle.
Scenario - The pitot tube is blocked and the drain hole is also blocked. What happens to the airspeed indicator?
ASI needle freezes at the speed when the blockage occurs, and stops responding.
Scenario - The pitot tube is blocked but the drain hole is open, what happens to the airspeed indicator?
ASI goes to zero, pressure cannot build up and ram air escapes through the hole.
