Aero1Ch3

Front 1

• Steady airflow

Back 1

exists if at every point in the airflow static pressure, density, temperature, and velocity remain constant over time. A particle of air follows the same path as the preceding particle.

Front 2

• Streamline

Back 2

is the path that air particles follow in steady airflow.

Front 3

• Streamtube

Back 3

a collection of streamlines forms a streamtube, which contains a flow just as effectively as a tube with solid walls. A streamtube is a closed system, therefore total mass and total energy must remain constant.

Front 4

• Continuity Equation

Back 4

A1V1 = A2V2

Front 5

Describe the relationship between airflow velocity and cross sectional area within a streamtube

Back 5

• If the cross sectional area decreases on one side of the equation, the velocity must increase on the same side so both sides remain equal. Velocity and area in a streamtube are inversely related

Front 6

• Bernoulli’s Equation

Back 6

PT = PS + q

• PT = Total pressure, also called Head Pressure (HT) equals the sum of Static Pressure (PS) + dynamic pressure (q = ½ρV2)

Front 7

Describe the relationship between total pressure, static pressure, and dynamic pressure within a streamtube

Back 7

• As with total energy, total pressure also remains constant within a closed system. As area in a streamtube decreases, velocity increases, therefore, “q” must increase(q contains V2). Since q increases, PS must decrease.

Front 8

List the components of the pitot static system

Back 8

• The pitot static system consists of the pitot-tube that senses total Pressure and a static port that senses ambient static pressure and a mechanism to compute and display dynamic pressure. (connected to a "black box")

Front 9

• Pitot Tube

Back 9

collects total pressure (PT)

Front 10

• Static Pressure Port

Back 10

collects ambient static pressure (PS)

Front 11

• Black Box

Back 11

Takes static pressure and subtracts it from the total pressure with a diaphragm. Through a series of springs and levers, the remaining static pressure, which is equal to dynamic pressure, is displayed on a pressure gauge inside the cockpit…the IAS gauge. (Figure 1.3-5)

q = PT - PS

Front 12

• Indicated Airspeed (IAS)

Back 12

instrument indication for the dynamic pressure the airplane is creating during flight.

Front 13

• Calibrated Airspeed (CAS)

Back 13

IAS corrected for instrument error-installation and position error. (Often ignored in calculations)

Front 14

• Equivalent Airspeed (EAS)

Back 14

Calibrated Airspeed corrected for Compressibility Error. EAS = TAS at sea level on a standard day that produces the same dynamic pressure as the actual flight condition (often ignored)

Front 15

• True Airspeed (TAS)

Back 15

actual velocity at which an airplane moves through an air mass. It is EAS corrected for Density. TAS is IAS (CAS and EAS are very minor and ignored) corrected for the difference between the local air density (ρ) and the density of the air at sea level on a standard day (ρo)

Front 16

• TAS will equal IAS only under ___________, sea level conditions

Back 16

standard day

Front 17

• Since air density decreases when you increase temperature or altitude, if IAS remains constant while climbing from sea level to some higher altitude, TAS must _________.

Back 17

increase

Front 18

TAS equation

Back 18

√(ρo/ρ) ∙ IAS

Front 19

• Ground Speed

Back 19

measure of airplanes speed over ground. TAS corrected for wind.

GS = TAS – headwind or GS = TAS + tailwind

Front 20

• Mach number

Back 20

(M)- ratio of airplane’s true airspeed to the local speed of sound

M = (TAS/LSOS)

Front 21

Describe the effects of altitude on Mach number and critical Mach number

Back 21

• An increase in altitude would increase Mach number and Critical Mach number because the local speed of sound would decrease. The speed of sound is temperature dependant and an increase in altitude results in a decrease in temperature which also reduces the speed of sound.