Aircraft Characteristics and Performance Flashcards
What are the motions of an aircraft called and around which axis does the motion take place?
Yaw - Around the vertical or normal axis
Roll - Around the Longitudinal Axis
Pitch - Around the lateral axis
Which control surfaces affect the motion of an aircraft?
Ailerons - Roll
Rudder - Yaw
Elevators - Pitch
What are the 2 types of drag called?
Profile drag - caused by the shape of the aircraft
Induced drag - Caused by the wings generating lift
What happens to each type of drag as airspeed increases?
Profile drag increases
Induced drag decreases
How does Bernoulli’s Principle relate to an aerofoil?
The top curved surface forces the air to travel faster over the top of the wing compared to the air underneath the wing. This leads to an increase in the dynamic pressure and a reduction in the static pressure on the top of the wing. High pressure moves towards low pressure causing the wing to rise.
What is a chord line?
It is a straight line joining the leading edge and the trailing edge of a wing
What is a chord line used for?
To calculate the angle of attack between the wing and the relative airflow
What is a flap?
It is a trailing edge high lift device
How does a flap work?
Increases lift by increasing the curvature of the wing
What is a slat?
A leading edge high lift device
What is a slot?
The space between the slat and the wing. It helps direct air over the wing when the wing is operating at particularly high angles of attack
What does an elevator trim tab do and how does it work?
Removes excess force from the control wheel. It operates in the opposite direction to the elevator. For example, if the elevator is needed to be held up, the trim tab would be down.
How does reaction propulsion work?
Either a small acceleration to a small amount of air or a large acceleration to a small amount of air
What are the stages of an internal combustion engine?
Intake, compression, combustion, exhaust
Name 3 advantages to a piston engine
i) More robust and easier to maintain
ii) |Lower temperatures and pressure so more fail safe
iii) Cheaper to manufacture
Name 3 disadvantages to a piston engine
i) Relatively expensive fuel
ii) Lower ceiling
iii) More wear and tear due to vibration
What is a propeller?
A means of converting engine power into propulsive force
What happens to a blade pitch and why?
Blade pitch increases as you move closer to the hub. This is because the tips are moving faster than the propeller closer to the hub. Increased blade pitch results in a constant amount of lift along the whole length of the blade.
What does the turbine in a gas turbine engine do?
Only drives the other parts of the engine. Does not produce any propulsive force
Name 3 advantages to a gas turbine engine
i) Faster
ii) Relatively light engine with few moving parts
iii) Better climb performance
Name 3 disadvantages to a gas turbine engine
i) High initial cost
ii) Less manoeuvrable at low level
iii) Delay in engine take up time (spool time)
How does a jet engine work?
Air is taken in through the air intake and compressed in the compressor. The compressed fuel/air mixture is burned and the hot air is expelled through the turbine causing it to turn. The exhaust causes an equal and opposite reaction forwards
What turbo prop configurations are there?
i) Direct drive turbine
ii) Free turbine
iii) Two spool (compound) turbine
Name 3 advantages to a turboprop
i) More manoeuvrable at low speeds
ii) Quicker transition from approach to overshoot
iii) Quiet
Name 3 disadvantages to a turboprop
i) Lower cruising level than jet engines
ii) Relatively higher initial build cost
iii) Greater frontal area causes more drag
What thrust reverse systems are available?
Hot Stream - Post turbine
Cold Stream - Post compressor
What is the artificial horizon?
A gyroscope instrument that indicates the attitude of the aircraft. Used when flying in poor visibility, over expanses of water or at night.
What kind of gyro is fitted to an artificial horizon?
An Earth gyro (A free gyro which is aligned to the Earth with a pendulum)
What is gyroscopic progression?
Any force which is applied to a gyro causes a change of direction of axis but at 90 degrees in the direction of rotation
