Pitot-Static System

Summary

This script delves into the pitted static system, crucial for powering flight instruments like the airspeed indicator, altimeter, and vertical speed indicator. It explains how these instruments rely on air pressure principles, distinguishing between static, dynamic, and total pressures. The script also covers the components of the pitted static system, including the pitted tube and static port, their functions, potential errors, and correction measures, emphasizing the importance of accurate pressure measurement for safe flight operations.

Takeaways

• 😀 The pitted static system is crucial for providing information to three basic flight instruments: the airspeed indicator, altimeter, and vertical speed indicator.
• 📚 Basic flight instruments, often called the 'six pack,' include the airspeed indicator, attitude indicator, altimeter, turn coordinator, heading indicator, and vertical speed indicator.
• 🔍 The pitted static system measures air pressure to power the airspeed indicator, altimeter, and vertical speed indicator, while the attitude, heading, and turn coordinator rely on gyroscopic principles.
• ⚖️ Static pressure, also known as atmospheric pressure, is the pressure exerted by air on objects within the atmosphere and varies mainly with altitude.
• 📉 As altitude increases, static pressure decreases, which affects the readings of flight instruments that rely on air pressure measurements.
• 💨 Dynamic pressure is the pressure exerted by air on a moving object and is directly related to the speed of the aircraft and the air density.
• 🔢 Total pressure, or pitot pressure, is the sum of static and dynamic pressures and is measured by the pitot tube to provide accurate airspeed readings.
• 🛠 The pitot tube must be aligned with the aircraft's longitudinal axis and located in an area free from airflow interference to measure total pressure accurately.
• ❄️ Pitot tubes incorporate a heating system to prevent icing, which can cause errors in pressure measurement.
• 🚧 Position errors can occur with the pitot tube during high angles of attack, affecting the accuracy of airspeed readings.
• 🔄 The static port measures static pressure and is designed to prevent dynamic pressure from affecting its readings, but it can still be subject to position errors during skids or slides.

Q & A

What is the 'pitted static system' and why is it important for an aircraft?

The pitted static system is a critical component in an aircraft that measures air pressure to power key flight instruments such as the airspeed indicator, altimeter, and vertical speed indicator. It is important because it provides essential information about the aircraft's speed, altitude, and vertical velocity, which are crucial for safe and effective flight operations.

What are the six basic flight instruments commonly referred to as the 'six pack'?

The 'six pack' refers to the airspeed indicator, attitude indicator, altimeter, turn coordinator, heading indicator, and vertical speed indicator. These instruments provide vital information about the most important parameters for flying an airplane.

How do the airspeed indicator, altimeter, and vertical speed indicator operate?

These instruments operate using air pressure. They measure different types of air pressure, such as static pressure, dynamic pressure, and total pressure, to provide readings on airspeed, altitude, and vertical velocity, respectively.

What is static pressure and how does it vary with altitude?

Static pressure, also known as atmospheric pressure, is the pressure that air exerts on objects within the atmosphere. It is evenly distributed around all objects and is always present, regardless of whether the object is stationary or moving. Static pressure varies mainly with altitude; as altitude increases, the static pressure decreases because there is less air above exerting weight.

Can you explain the concept of dynamic pressure?

Dynamic pressure is the pressure that air exerts on an object moving through it. It depends directly on the speed at which the aircraft is moving and the density of the air. As the aircraft's speed increases, so does the dynamic pressure, and vice versa.

What is total pressure, and how is it related to static and dynamic pressure?

Total pressure, also known as pitot pressure, is the sum of static pressure and dynamic pressure. It corresponds to the pressure experienced by an aircraft moving through the air, combining both the pressure from the air's weight (static) and the pressure from the air's resistance to the aircraft's motion (dynamic).

What is the purpose of the pitot tube in the pitted static system?

The pitot tube measures the total pressure of the air as the plane moves through it. It is designed to accurately measure the pressure with which the air impacts the aircraft, combining both static and dynamic pressures.

Why is the pitot tube susceptible to icing, and how is this issue addressed?

The pitot tube is susceptible to icing because it is an exposed object that experiences airflow. Icing can block the main intake hole and cause errors in pressure measurement. To address this, the pitot tube incorporates a heating system with electrical resistances that can melt any ice when activated from the cockpit.

What is a static port, and how does it measure static pressure?

A static port is a small hole located on the side of the aircraft's fuselage that measures the air's static pressure or atmospheric pressure. It is designed to allow only static pressure to enter, not dynamic pressure, by being positioned in a way that captures the pressure exerted in all directions by the air.

What are position errors, and how do they affect the measurements from the pitot tube and static port?

Position errors are inaccuracies in the measurements from the pitot tube and static port due to the aircraft's orientation or maneuvers. For example, at high angles of attack, the airflow may not be parallel to the pitot tube, causing slight errors in total pressure measurement. Similarly, during a skid or slide, part of the dynamic pressure may enter the static port, affecting the static pressure measurement.

Why are there alternate static sources in aircraft, and how do they work?

Alternate static sources are additional static ports that can be activated if the primary static port gets blocked. They are usually located inside the cabin to avoid potential blockage due to external conditions. However, they measure slightly different static pressures from the exterior, and this difference is accounted for in the calibration tables used for flight instruments.