Fluids
Viscosity is a fluid’s resistance to _______.
Flow
What atmospheric conditions will reduce takeoff and climb performance? Name Two.
High temperature, high relative humidity, and high density altitude
Which factor would tend to increase the density altitude at a given airport?
Increase in Temperature
Knowing the pressure altitude is important to aircraft performance because it can be used as a tool to arrive at _______.
Density Altitude
_______ decreases at 1’’Hg per 1,000 foot increase in altitude.
Barometric Pressure
Which statement is true about an object moving through a fluid?
Viscosity changes according to the size of the object.
The object moves faster if the fluid is more viscous.
Fluid friction increases as the object’s velocity increases.
Less viscosity means more fluid friction.
Fluid friction increases as the object’s velocity increases.
How is density calculated?
d = m/v
What is the formula for calculating Density Altitude?
PA + [120 (OAT ‒ ISA) ]
Pressure altitude corrects for the difference between _______ and standard pressure.
barometric pressure
What are the standard temperature and pressure values for sea level?
15 degrees C and 29.92” Hg.
The Magnus Effect occurs because a spinning object drags the air around it. The air being dragged by the object interacts with the surrounding air to create regions of _______.
high and low pressure
The density of which substance is closest to the density of air? options: glue, honey, oil, or water
Water
The primary reason for computing density altitude is to determine airplane performance. True or False
True
Pressure altitude is calculated from (29.92 – 28.92) ✕ 1,000 + 3,500. What information do these numbers give?
The barometric pressure is 28.92 ”Hg and the elevation is 3,500 feet
The “standard day” serves as a universal baseline for measuring _______.
atmospheric pressure
The Coanda Effect is the tendency for a jet of fluid to _______.
attach to a convex or bulging surface
Objects with the same _______ but different masses have different densities.
volume
Explain what limits an aircraft’s ability to perform and fly at extremely high altitudes.
Air density decreases as altitude increases. This is why every airplane has a flight ceiling, an altitude
above which it cannot fly. As an airplane ascends, it reaches a point where there isn't enough air to generate the lift required to overcome the airplane's weight, enough air for the engine to burn the fuel, or enough air for the propeller to convert engine power into thrust.
Which of the following are units of measure for atmospheric pressure? Name One.
millibars (mb), pounds per square inch (PSI), and inches of mercury (Hg)
What do the following variables in this equation stand for? DA = PA + [120 (OAT ‒ ISA)]
DA = density altitude
PA = pressure altitude
OAT = outside air temperature
ISA = standard temperature at the calculated pressure altitude
In what way is the Coanda Effect similar to the Magnus Effect?
They both describe the movement of air molecules creating regions of high and low pressure.
Explain why an aircraft will have diminished performance on a hot day at a high-altitude airport.
Air density decreases as altitude increases. This means that the air is less dense at airports situated at higher elevations. However, other factors—such as temperature and air pressure—can also affect air density, causing it to increase or decrease even as altitude remains constant. Airports in areas with higher temperatures and at higher elevations have higher density altitudes. This means the air is less dense, and so there is less air for the engine to use to create power, to lift the wings, and to push through the propellers to generate thrust. This leads to longer takeoff and landing distances and a general decrease in aircraft performance.
An airport has an elevation of 1,700 feet. A density altitude of 2,200 feet means that an aircraft will perform as if it is ________ above sea level.
2,200'
Atmospheric pressure is (proportional/inversely proportional) _______ to air density.
proportional
Explain how the Magnus Effect works and give a real-world example.
The Magnus Effect occurs because a spinning object drags the air around it. The air being dragged by the object interacts with the surrounding air to create regions of high and low pressure. If the region of low pressure is imbalanced, the object is pulled toward the region of lowest pressure. This allows baseball pitchers or soccer players to curve the path of their balls by varying the amount of spin they put on the balls