Aircraft Stalling and Slat Extension

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Questions and Answers

What is the force that moves an aircraft through the air?

Thrust (correct)

Lift

Drag

Weight

What is the primary purpose of flaps on an aircraft?

To shorten the takeoff distance only

To decrease the angle of descent for landing

To increase the stall speed

To reduce the speed at which an aircraft can be safely flown (correct)

What is the result of accelerating a mass of gas rearward in an aircraft engine?

The engine is damaged

Thrust is generated in the opposite direction (correct)

The aircraft is propelled backward

The engine is cooled

What is the effect of deploying slats on an aircraft?

An increase in the coefficient of lift Signup and view all the answers

What is a common use of slats on aircraft?

Simplifying wing design on low-speed aircraft Signup and view all the answers

What is the shape of a propeller blade?

Aerofoil Signup and view all the answers

What is the purpose of slats when landing or performing maneuvers?

To allow the aircraft to fly at slower speeds Signup and view all the answers

What is the purpose of thrust in an aircraft?

To overcome drag Signup and view all the answers

What is the primary factor that determines the stalling speed of an aircraft?

Altitude and configuration Signup and view all the answers

What occurs when the critical angle of attack is exceeded?

A sudden reduction in lift occurs Signup and view all the answers

What is the variable that represents the air density in the general airplane lift equation?

Signup and view all the answers

What is the typical range of the critical angle of attack for most subsonic airfoils?

8 to 20 degrees Signup and view all the answers

What determines the magnitude of thrust?

The amount of gas accelerated and the difference in velocity Signup and view all the answers

What is the purpose of a stick shaker in an aircraft?

To simulate the feel of a buffet Signup and view all the answers

What is the effect of increasing the platform area (S) in the general airplane lift equation?

An increase in the lift produced at a lower airspeed Signup and view all the answers

What is the result of the propeller accelerating a large mass of air rearwards?

The aircraft is propelled forward Signup and view all the answers

What is the purpose of flaps in normal flight?

To minimize drag Signup and view all the answers

What happens to the lift coefficient as the angle of attack increases beyond the critical angle?

It begins to decrease Signup and view all the answers

What happens to an aircraft's angle of attack as it slows down in steady, unaccelerated flight?

It increases to create the same lift Signup and view all the answers

What is the reaction force described by Newton's second and third laws?

Thrust Signup and view all the answers

What is the primary cause of a stall in fixed-wing flight?

Exceeding the critical angle of attack Signup and view all the answers

What is the difference between automatic and fixed slats?

Fixed slats are permanently extended, while automatic slats lie flush with the wing leading edge Signup and view all the answers

What happens when an aircraft's angle of attack reaches the critical stall angle?

The aircraft begins to descend Signup and view all the answers

What is the effect of deploying flaps on an aircraft's drag?

An increase in drag Signup and view all the answers

What is the effect of flow separation on the wing's ability to create lift?

It decreases lift and increases drag Signup and view all the answers

What is the primary function of a propeller in an aircraft?

To produce thrust Signup and view all the answers

What is a characteristic of a stall in an unpowered glider aircraft?

The lift coefficient suddenly decreases Signup and view all the answers

What is the primary factor that determines the critical angle of attack?

All of the above Signup and view all the answers

What is the correlation between airspeed and stalling speed?

Airspeed is only indirectly related to stalling speed Signup and view all the answers

What happens to the lift of an aircraft as it slows down in steady, unaccelerated flight?

The lift decreases as the speed slows down Signup and view all the answers

Study Notes

FLAP & SLATS

Flaps are hinged surfaces mounted on the trailing edges of an aircraft's wings to reduce the speed at which an aircraft can be safely flown and increase the angle of descent for landing.
Flaps shorten takeoff and landing distances by lowering the stall speed and increasing drag.
Slats are aerodynamic surfaces on the leading edge of an aircraft's wings, allowing the wing to operate at a higher angle of attack, producing a higher coefficient of lift, and enabling the aircraft to fly at slower speeds or take off and land in shorter distances.

LIFT EQUATION

The general airplane lift equation is: L = (1/2) × ρ × V^2 × S × CL
Increasing the area (S) and lift coefficient (CL) can generate lift at a lower airspeed (V).

SLATS

Types of Slats:
- Automatic: lies flush with the wing leading edge until reduced aerodynamic forces allow it to extend.
- Fixed: permanently extended, used on specialist low-speed aircraft or when simplicity takes precedence over speed.
- Powered: extension can be controlled by the pilot, commonly used on airliners.

STALL

A stall is a reduction in lift coefficient generated by a foil as the angle of attack increases beyond a critical point.
The critical angle of attack is typically around 15 degrees, but can vary depending on the fluid, foil, and Reynolds number.
Stalling occurs when the wing's ability to create lift is hindered by separated flow, resulting in decreased lift and increased drag.

THRUST

Thrust is a reaction force described by Newton's second and third laws, generated by expelling or accelerating mass in one direction.
Thrust is used to overcome the drag of an aircraft, generated by the engines through a propulsion system.
The propulsion system must be in physical contact with a working fluid to produce thrust, which is often generated through the reaction of accelerating a mass of gas.

PROPELLER

The propeller blade is an aerofoil, with definitions for chord, camber, thickness/chord ratio, and aspect ratio similar to those for the wing.
The propeller accelerates a large mass of air rearwards, propelling the aircraft forward.

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Description

This quiz covers the concept of stalling in aircraft, including the critical angle of attack, and the use of slat extension to control it.