Property of Lear Siegler

Property of Lear Siegler

PHYSICS OF THE ATMOSPHERE

TERMINAL LEARNING OBJECTIVE At the completion of this lesson, the student will: ACTION: Demonstrate an understanding of the atmosphere’s physical properties and their impact on the operation of the TH-67 pressure instruments. CONDITION: In a classroom environment given information on the pressure instruments and the atmosphere. STANDARD: Answer questions pertaining to the atmosphere’s physical properties and their impact on the operation of the TH-67 pressure instruments. Receive a “GO” by correctly answering the required number of questions on criterion referenced examination 011-0050. Property of Lear Siegler

A: Enabling Learning Objective Action: Identify the characteristics of the standard atmosphere Condition: Given information about the standard atmosphere Standard: IAW FM 3-04.240 and FAA-H-8083-25A, Pilot’s Handbook of Aeronautical Knowledge. Property of Lear Siegler

The “Standard Atmosphere” “A hypothetical vertical distribution of atmospheric temperature, pressure, and density which by international or national agreement is taken to be representative of the atmosphere for the purpose of altimeter calibrations, aircraft design, performance calculations, etc.” Property of Lear Siegler

29.92” 53,000 90% 18,000 50% Sea Level Sea Level Property of Lear Siegler

Standard Pressure Lapse Rate 7500’ 22.42”Hg 5000’ 24.92”Hg 4000’ 25.92”Hg 1” Hg per 1000’ 3000’ 26.92”Hg 2000’ 27.92”Hg 1000’ 28.92”Hg MSL 29.92”Hg Property of Lear Siegler

2°C per 1000’ Standard Temp Lapse Rate 7500’ 0°C 5000’ 5°C 4000’ 7°C 3000’ 9°C 2000’ 11°C 1000’ 13°C MSL 15°C Property of Lear Siegler

29.92”Hg 23°C 28.92”Hg 15°C AIR DENSITY 29.92”Hg 15°C 29.92”Hg 15°C 29.92”Hg 15°C Property of Lear Siegler

Good Bad AIR DENSITY Press H L Temp L H Hum L H

Questions? MMMMMMMMOVING Property of Lear Siegler

B: Enabling Learning Objective Action: Identify the pressures used in the pitot static system Condition: Given information about the pitot static system pressures Standard: IAW FM 3-04.240 MMMMMMMMOVING Property of Lear Siegler

Weight of a column of air Static Pressure -- Impact Pressure -- Static + Dynamic Dynamic Pressure – Additional pressure caused by air in motion Property of Lear Siegler

Stagnation point Property of Lear Siegler

Static pressure only Static + Dynamic Impact pressure = Note: Impact = Ram = Total = Pitot Pressure Property of Lear Siegler

Construction of the Pitot System HEATER LEFT RIGHT STATIC VENTS PITOT TUBE Property of Lear Siegler

Construction of the Pitot System Notice that the Pitot Tube goes only to airspeed indicator! The Static Pressure is vented to all three instruments.

Construction of the Pitot System The diaphragm in the Airspeed Indicator is connected to the Pitot Tube. It only senses Pitot Pressure. The case is vented to Static Pressure.

Construction of the Pitot System The diaphragm in the Vertical Speed Indicator is vented to Static Pressure. The case is vented to Static Pressure through a calibrated leak.

Construction of the Pitot System The aneroids in the Altimeter are sealed. The case is vented to Static Pressure.

Any Questions? MMMMMMMMOVING Property of Lear Siegler

C: Enabling Learning Objective Action: Identify the operational characteristics of the airspeed indicator Condition: Given information about the airspeed indicator Standard: IAW FM 3-04.240 Property of Lear Siegler

AIRSPEED INDICATOR Property of Lear Siegler

LEFT RIGHT STATIC VENTS PITOT TUBE Property of Lear Siegler

STATIC VENT PITOT TUBE Property of Lear Siegler

IMPACT PRESSURE PRESSURE STATIC Property of Lear Siegler

Impact pressure = Static + Dynamic IMPACT PRESSURE PRESSURE STATIC Property of Lear Siegler

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D: Enabling Learning Objective Action: Identify the uses of the airspeed indicator Condition: Given information on the uses of the airspeed indicator Standard: IAW FM 3-04.240 Property of Lear Siegler

Uses for the airspeed indicator 1: Keep aircraft within “Never Exceed Speed" 2: Determine best operational speed for best climb, best endurance, and best range 3: Determine rate of movement for navigation 4: Aircraft attitude Airspeed fast-Pitch attitude low Airspeed low-Pitch attitude high Property of Lear Siegler

E: Enabling Learning Objective Action: Identify the errors associated with the airspeed indicator Condition: Given information about airspeed indicator errors Standard: IAW FM 3-04.240 Property of Lear Siegler

ERRORS Instrument Error – Minor, caused by friction Installation Error – Caused by misalignment of the pitot tube and/or the static vents with the relative wind Density Error – Caused by changes in air density Property of Lear Siegler

TRUE AIRSPEED (TAS) IS THE SAME, AIR IS LESS DENSE AT ALTITUDE, THEREFORE, CALIBRATED AIRSPEED (CAS) IS LESS THAN TAS. Property of Lear Siegler

CAS IS THE SAME, AIR IS LESS DENSE AT ALTITUDE, THEREFORE, TAS IS MORE THAN CAS AT ANY ALTITUDE ABOVE ZERO FEET DENSITY ALTITUDE. Property of Lear Siegler

F: Enabling Learning Objective Action: Identify the types of airspeed Condition: Given information about types of airspeed Standard: IAW FM 3-04.240 Property of Lear Siegler

Types of Airspeed IAS – Indicated Airspeed –read from the airspeed indicator CAS – Calibrated Airspeed –Indicated Airspeed corrected for installation error TAS – True Airspeed -Calibrated Airspeed corrected for density error Property of Lear Siegler

Airspeed Indicator in Review… Can you identify the pressures used, the errors and the types of airspeed? Property of Lear Siegler

G: Enabling Learning Objective Action: Identify the operational characteristics of the vertical speed indicator Condition: Given information about the operation of the vertical speed indicator Standard: IAW FM 3-04.240 Property of Lear Siegler

Vertical Speed Indicator Property of Lear Siegler

LEFT RIGHT STATIC VENTS PITOT TUBE Property of Lear Siegler

STATIC VENTS PITOT TUBE Property of Lear Siegler

Calibrated Leak Property of Lear Siegler

Property of Lear Siegler