Lesson 2 Flashcards
Define stall
A stall is defined as a sudden reduction in lift generated by an aerofoil when a critical AOA is reached.
Lift to drag ratio
Lift/drag
What is the typical critical angle
15°.
Why is wing root stall preferred
As there is no need for flight crew input
Why is wing tip stall more dangerous
The centre of lift moves towards the root and also forward to the centre of gravity Subsequently, the aircraft rotates to the nose-up position, the AOA increases, and the stall condition gets worse.
What is used to prevent wing tip stalling on smaller aircraft
A stall strip is a knife edge
What is used to prevent wing tip stalling on bigger aircraft, and where is it located
Slats are used to prevent
The slats are located at the leading edge of the wing tips wing tip stall on some larger aircraft.
What are the most common types of contamination
Snow and ice formations
What effect can the build up of ice on aircraft
extra weight and drag, loss of lift, and the freezing or unbalancing of control surfaces.
When will frost form on an aircraft
Frost will form in clear air when an aircraft has been parked overnight in below zero temperatures. It can also form when an aircraft flies from sub-zero temperatures into warm moist air such as in a descent.
When is rime ice formed
Rime ice is formed when small, supercooled water droplets freeze on contact with a surface that is below freezing temperature..
When is clear ice formed
forms when flying in areas with a high concentration of large, supercooled water droplets.
Why is clear ice most dangerous
as it is heavy, dense, tough, difficult to see, and it adheres itself firmly to the airframe surface.
Where is the total weight of an aircraft represented at
The total weight of the aircraft is represented at the centre of gravity and is a vector that is always directed downward toward the centre of the earth.
What is Lift
Lift is a force vector which acts perpendicular to the direction of flight.
What is thrust
Thrust is a force vector which acts in the direction of flight.
What is drag
Drag is a force vector which opposes the direction of flight.
What does the glide ratio state
The ratio of the distance forward to the distance downward is called the glide ratio.
Sum for glide ratio
Change in distance/ change in height
How do you get more lift when climbing
Increase the thrust
What are the primary factors most affected by performance
The take-off and landing distance
Rate of climb
Ceiling
Payload
Range
Speed
Manoeuvrability
Stability
Fuel economy
What are the 3 variables that affect the range versus speed
Aircraft gross weight
Altitude
The external aerodynamic configuration of the aircraft
What happens to lift when an aircraft banks
lift acts inward toward the centre of the turn, as well as upward.
What happens in a slipping turn
the aircraft is not turning at the rate appropriate to the bank being used, since the aircraft is yawed toward the outside of the turning flight path.
What is a load factor
the load factor is the ratio of lift of an aircraft to its weight.
What letter is used for load factor
“g”
What are the characteristics of a stall
distinctive loss of lift, which is usually noted by a sudden pitch down of the nose of the aircraft. There may be warnings such as buffeting before this occurs.
What factors is the v-n diagram dependent on
The aircraft’s gross weight
The configuration of the aircraft’s flaps, landing gear position, etc.
The applicable altitude
What is lift augmentation
Lift augmentation systems are devices installed on the wing of an aircraft to produce an increase in the lift at a given speed.
When is the aircraft most likely to stall and why
Take off and landing as its speed is the lowest
What devices are used to increase the max lift coefficient
Flaps: these include trailing-edge flaps and leading-edge flaps
Slats and Slots: either automatic or controllable by the pilot
Boundary Layer Control: used to re-energise the boundary layer
What is a plain flap
The plain flap is a basic flap design hinged to the wing’s trailing edge and pivots down when extended.
What do Mel’s flaps look like
Beefy
What is a split flap
split flaps consist of two sections. The fixed upper part is an extension of the top trailing-edge of the wing while the lower split flap is movable and pivots down from its hinges on the lower wing surface to generate drag.
What is a slotted flap
The slotted flap is a type of aircraft flap designed with a gap between the wing and flap, allowing high-pressure air beneath the wings to flow, reducing air separation levels while increasing lift
What is a fowler flap
flaps are installed in sections on the upper wing surface and extend rearwards on a set of rails or tracks before dropping to increase both the chord and then the camber. They are the most common typeof slap.
What are Krueger flaps
high lift tools fitted to the bottom of an aircraft’s wing leading edge.
What are cuffs
Leading-edge cuffs, like leading-edge flaps and trailing-edge flaps, are used to increase both CL-MAX and the camber of the wings.
What do slats prevent
Slats prevent flow separation by supplying more energy to the boundary layer.
What do vortex generators help with
improve the performance and controllability of the aircraft, particularly at low speeds, in the climb, and at high angles of attack.
What are winglets?
Winglets are small, upturned structures on the end of an aircraft’s wings. When air flows over the wing, it creates a vortex at the tip of the wing, which creates a lot of drag and turbulence.
What are the benefits of installing winglets
Reduced fuel consumption
Improve performance
Lower emissions
Increased range
Define stability
Stability is the essential quality of an aircraft to correct for conditions that may disturb its equilibrium and to return to, or to continue the original flight path.
What is the vertical axis also known as
Yaw
What is the lateral axis also known as
Pitch
What is the longtitudinal axis also known as
Roll
What two areas in aircraft does stability affect
Manoeuvrability
Controllability
What is manoeuvrability
The quality of an aircraft that allows it to be manoeuvred easily and to withstand the stresses imposed by manoeuvres. It is controlled by the aircraft’s weight, inertia, size and location of flight controls, structural strength, and powerplant. It too is an aircraft design characteristic.
What are the three kinds of static electricity
Positive static stability
Neutral static stability
Negative static stability
What is positive static stability
An aircraft that has positive static stability has the tendency to return to the original state of equilibrium after being disturbed.
What is Neutral Static Stability
An aircraft that has neutral static stability tends to stay in its new attitude when it’s disturbed.
What is negative static stability
An aircraft that has negative static stability tends to continue moving away from its original attitude when it’s disturbed.
What is dynamic stability
Dynamic stability refers to the aircraft response over time when disturbed from a given pitch, yaw, or bank and relates to whether an aircraft will continue to oscillate after a disturbance
What is positive dynamic stability
Aircraft with positive dynamic stability have oscillations that dampen out over time and because it is positive, it returns toward its equilibrium state.
What is neutral dynamic stability
Aircraft with neutral dynamic stability have oscillations that never dampen out. In the diagram below, pitching up a trimmed, neutrally dynamic stable aircraft, will pitch nose low, then nose high again, and the oscillations will continue, in theory, forever.
What is negative dynamic stability
Aircraft with negative dynamic stability have oscillations that get worse over time. The diagram below shows how once displaced, the pitch oscillations become more and more amplified.
What does longitudinal stability involve
the tendency for the nose to pitch up or pitch down, rotating around the lateral axis.
What factors does longitudinal stability dependent on
Location of the wing with respect to the centre of gravity
Location of the horizontal tail surfaces with respect to the centre of gravity
Area or size of the tail surfaces
When does positive longitudinal stabilityoccar
when the centre of gravity, as the result of all aircraft weights, is forward of the aerodynamic centre (called the neutral point) which is the centre of all lift forces.
What’s the purpose of dihedral angles
Restore level flight
Where is the sideslip angle
between the aircraft centreline and the sideslip direction.
