SIFT Reading Comprehension Questions and Answers — Questions and Answers
Question 1: Read the following passage and answer the question below. "The four fundamental forces affecting an aircraft in flight are lift, weight, thrust, and drag. For an aircraft to maintain straight-and-level, unaccelerated flight, these forces must be in equilibrium. Lift, the upward aerodynamic force, must be equal to weight, the downward force of gravity. Thrust, the forward force from the propulsion system, must be equal to drag, the rearward-acting resistive force. If thrust is increased while lift and weight remain in balance, the aircraft will accelerate. Conversely, if drag becomes greater than thrust, the aircraft will decelerate. A change in one force necessitates a change in another to maintain the desired state of flight." According to the passage, what is the direct result of thrust being less than drag?
- The aircraft will climb.
- The aircraft will accelerate.
- The aircraft will decelerate. (Correct answer)
- The aircraft's weight will increase.
Correct answer: The aircraft will decelerate.
The passage explicitly states, 'Conversely, if drag becomes greater than thrust, the aircraft will decelerate.' This indicates a direct cause-and-effect relationship between the imbalance of thrust and drag and the aircraft's motion.
Question 2: Read the following passage and answer the question below. "While many individuals contributed to the concept of vertical flight, Russian-American engineer Igor Sikorsky is widely credited with developing the first practical single-rotor helicopter. His design, the VS-300, which first flew in 1939, established the single main rotor and tail rotor configuration that would become the standard for the vast majority of helicopters. Unlike earlier multi-rotor designs that were often complex and unstable, Sikorsky's configuration provided effective control and counteracted the physics of torque—the tendency of the main body of the helicopter to spin in the opposite direction of the main rotor. This breakthrough was pivotal in transitioning the helicopter from an experimental concept to a viable aircraft." What was the primary problem that Sikorsky's single main rotor and tail rotor design successfully solved?
- Inefficient fuel consumption in early designs.
- The tendency of the helicopter's body to rotate due to torque. (Correct answer)
- The inability of early helicopters to achieve high altitudes.
- The structural weakness of multi-rotor systems.
Correct answer: The tendency of the helicopter's body to rotate due to torque.
The passage clearly states that Sikorsky's configuration 'provided effective control and counteracted the physics of torque—the tendency of the main body of the helicopter to spin in the opposite direction of the main rotor.'
Question 3: Read the following passage and answer the question below. "Nap-of-the-earth (NOE) flight is a military aviation tactic predominantly used by helicopters to operate at extremely low altitudes, closely following the contours of the terrain. The principal objective of this flight profile is to use natural features like hills, valleys, and forests as cover to minimize detection by enemy radar, visual observation, and acoustic sensors. While highly effective for concealment and survivability, NOE flight is exceptionally demanding for the pilot. It requires immense concentration and rapid control inputs to navigate obstacles and avoid contact with the ground, making it one of the most challenging flight regimes." The passage implies that the main trade-off for the enhanced protection offered by NOE flight is:
- A significant increase in fuel consumption.
- A reduction in the aircraft's payload capacity.
- A heightened level of difficulty and risk for the pilot. (Correct answer)
- A slower overall speed to the objective.
Correct answer: A heightened level of difficulty and risk for the pilot.
The passage emphasizes that NOE flight is 'exceptionally demanding for the pilot' and requires 'immense concentration and rapid control inputs,' which implies a high level of difficulty and inherent risk. This is presented as the downside to its effectiveness for concealment.
Question 4: Read the following passage and answer the question below. "Spatial disorientation occurs when a pilot cannot correctly interpret the aircraft's attitude, altitude, or airspeed in relation to the Earth. This dangerous condition often arises in environments with poor visibility, such as in dense clouds or on a moonless night over water, where the natural horizon is obscured. In such conditions, pilots must rely on their flight instruments. However, the body's vestibular system, which provides our sense of balance, can create powerful, conflicting sensations that make a pilot feel the aircraft is turning or banking when it is not. Trusting these false sensations over the instruments can lead to loss of control." Which of the following is identified in the passage as a primary cause of spatial disorientation?
- A failure of the aircraft's primary flight instruments.
- High-G maneuvers that exceed pilot tolerance.
- Engine vibrations that interfere with vision.
- The loss of a visible horizon and reliable visual cues. (Correct answer)
Correct answer: The loss of a visible horizon and reliable visual cues.
The passage directly links spatial disorientation to 'environments with poor visibility... where the natural horizon is obscured,' forcing a reliance on instruments over potentially misleading bodily sensations.
Question 5: Read the following passage and answer the question below. "Many crucial flight instruments, such as the attitude indicator and heading indicator, depend on the principle of gyroscopic rigidity. A gyroscope consists of a rapidly spinning rotor mounted in gimbals, which allows it to maintain its orientation in space regardless of the movement of the aircraft around it. This stability provides a fixed reference plane. For example, the attitude indicator's gyroscope remains aligned with the Earth's horizon, presenting the pilot with an 'artificial horizon' to show the aircraft's pitch and bank. This function is indispensable during flight in instrument meteorological conditions where the actual horizon is not visible." According to the passage, what is the essential characteristic of a gyroscope that makes it useful in an attitude indicator?
- Its ability to precess at a calculated rate.
- Its low power consumption compared to other instruments.
- Its stability and resistance to changing its spatial orientation. (Correct answer)
- Its direct connection to the aircraft's control surfaces.
Correct answer: Its stability and resistance to changing its spatial orientation.
The passage highlights the principle of 'gyroscopic rigidity' and states that the rotor 'maintain[s] its orientation in space regardless of the movement of the aircraft around it.' This stability is the key characteristic.
Question 6: Read the following passage and answer the question below. "Bernoulli's principle is fundamental to understanding lift. It states that an increase in the speed of a fluid is accompanied by a decrease in its pressure. An airfoil, such as a wing or rotor blade, is designed with a curved upper surface and a flatter lower surface. As the airfoil moves through the air, the air that travels over the curved top surface must travel a longer distance than the air traveling along the bottom. Consequently, the air on top moves faster, resulting in lower pressure above the airfoil compared to the higher pressure below it. This pressure differential creates a net upward force, which is known as lift." Based on the passage, an airfoil generates lift because:
- The air pressure above the wing is greater than the pressure below it.
- The air pressure below the wing is greater than the pressure above it. (Correct answer)
- The air molecules push down on the top of the wing.
- The airfoil's forward motion displaces an equal weight of air.
Correct answer: The air pressure below the wing is greater than the pressure above it.
The passage explains that faster-moving air over the top surface creates lower pressure, while slower-moving air underneath creates higher pressure. It explicitly states, 'This pressure differential creates a net upward force, which is known as lift.' Therefore, the higher pressure is below the wing.
SIFT Reading Comprehension Questions and Answers
Read the following passage and answer the question below.
"The four fundamental forces affecting an aircraft in flight are lift, weight, thrust, and drag.
For an aircraft to maintain straight-and-level, unaccelerated flight, these forces must be in equilibrium.
Lift, the upward aerodynamic force, must be equal to weight, the downward force of gravity.
Thrust, the forward force from the propulsion system, must be equal to drag, the rearward-acting resistive force.
If thrust is increased while lift and weight remain in balance, the aircraft will accelerate.
Conversely, if drag becomes greater than thrust, the aircraft will decelerate.
A change in one force necessitates a change in another to maintain the desired state of flight."
According to the passage, what is the direct result of thrust being less than drag?