Principles of Flying Flashcards
What are the four forces that act upon an aircraft in flight?
Lift, Weight, Thrust, Drag
What are Newtons 1,2,3 Laws
1 - An object will continue moving in space at a constant velocity unless an external force is applied.
2 - if a force is applied to a body it will accelerate at a rate proportional to its mass and the force applied.
3 - For every action there is an equal and opposite reaction.
Where is an aircrafts centre of gravity? (CofG)
The poin t about which all gravitational moments add up to zero.
What is the equation for Newtons 2nd law?
f=ma
What is Pitch, Roll and Yaw?
Pitch - Nose moving up or down
Roll - Rotating left or right around longitudinal centreline
Yaw - Nose moving left or right around a vertical axis through the main rotor mast.
How does a vector differ from a line?
Both direction and magnitude
What is the front tip of an aerofoil called?
Leading Edge
What is the back tip of an aerofoil called?
Trailing Edge
What is the centre line in aerofoil called?
Chord Line
What is the cross in the middle of the thickest part called?
Centre of pressure
A symmetrical aerofoil has a mean chord that is?
Straight
The Angle of Attack (AoA) of an aerofoil is measured between the mean chord line and the?
Relative Air Flow
In nature, energy always flows from ( ) pressure to ( ) pressure
High pressure to low pressure
What is the lift equation
Lift=CL 1/2p v2 S
What do the components of the lift equation mean?
CL - Coefficient of lift
1/2p - Density of the air
V2 - Air velocity over the aerofoil
S - Aerofoil surface area
Will a helicopter generate the same amount of lift at 28,000ft and at sea level?
NO
The ability of a wing to provide lift, increases with its ( ) until the critical ( ) is reached (It is just one answer for both)
Angle of Attack
What are the two types of drag?
Zero lift drag (parasitic drag)
Lift dependant drag
What are characteristics of drag
The total of all air resistance to an object moving through it.
Acts parallel to and opposite of the flight path
Give three items that contribute to Induced drag (Lift dependant)
Surface (Skin) Friction Drag
Form Drag
Increased Angle of Attack
Give three items that contribute to Parasitic Drag
Extended Landing Gear
External tanks
Ordnance/Racks
Why is icing a hazard?
Increased aircraft weight
Changes the aerofoils shape
Decreases the lift being generated
Increases the drag being generated
What two things must be present for icing to occur?
Visible moisture
OAT lower than 2C
Wing tip vortices are what?
Two counter rotating cylindrical vortices
What are hazards of Wake Turbulance on a following aircraft?
Induced Roll and Yaw
Especially dangerous during take of and landing
Rare but can cause structural damage
What Gas Turbines commonly used in aviation?
Turbojet (F18)
Turboprop (PC21)
Turboshaft (Helicopter)
Turbofan (Airliners)
What is the work cycle of a gas turbine engine?
SUCK SQUEEZE BANG BLOW
What are the 4 sections of a gas turbine?
Intake
Compressor
Combustion
Turbine/Exhaust
When does the spark occur in a combustion chamber?
Engine start
Give an example of a conventional helicopter layout
MH-60R
Why is the tail rotor required for in convential helicopters?
Torque reaction
What is a teetering main rotor head?
Semi-Rigid rotor head (HUEY)
Simple and cheap
Prone to mast bumping
What are the characteristics of a fully articulated rotor head?
They are extremely complex and heavy and as a result are used primarily on larger helicopters.
The freedom of movement provided by mechanic hinges and bearings reduces vibration and rotational stress.
What are the characteristics of a rigid rotor head?
Simple and cheap
Flexible structures to allow blade movement
The manufactured twist in rotor blades is called what?
Washout
What is a defining characteristic of an assymetrical aerofoil main rotor blade?
Has a curved mean chord line
Describe the main rotor disk
Circular area swept by main rotors
Relative airflow vector for a rotary wing BVD is made up of what two components?
Rotational airflow & Induced Flow (IF)
Induced flow is caused by what?
Drawing air from above the rotor
The combination of Induced flow and rotational airflow creates what?
Relative airflow
Describe the path of the rotorblades during rotation
Tip Path Plane
What is the angle between the plane of rotation and the feather axis?
Coning angle
Total reaction is created by what?
Rotor Thrust and Rotor Drag
What is the opposing force to Rotor Drag?
Torque
The cockpit flight control changes the pitch angle of each main rotor blade individually as they cycle round the rotor mast
Cyclic
This cockpit flight control changes the pitch angle of all the main rotor blades at the same time
Collective
What is the swashplate assembly composed of?
Stationary (Control ring in EC135)
Rotating (Bearing Ring in EC135)
Which swashplate is used to transfer the cyclic and collective commands to the rotor blades through the Pitch Control Links?
Rotating
Which swashplates are raised/lowered when the pilot raises and lowers the collective?
Both
Why are there two cyclic control rods connected to the stationary swashplate?
One for pitch, one for roll
Four items that affect coning angle
Rotor RPM
Rotor thrust produced (blade pitch)
Weight of the helicopter
Dynamic loading due to manoeuvering (G Force)
To move the aircraft laterally we must tilt the…
Total Rotor Thrust vector
The 90degree lag between control input and the response by the rotor is termed
Phase Lag
Phase Lag can be compensated for by…
Advance Angle alone or,
Advance Angle and Control rigging
Flapping to equality of lift is…
Blade movement which equalises rotor thrust across the disc
Due to the principle of conservation of angular momentum, when rotor blades are coned up the RPM will…
Increase
Which conventional rotor head design would give a pilot the quickest response time?
Rigid/Semi-Rigid rotor head
Three metrics to measure Control Power
Immediacy (Time delay)
Rate (roll or pitch rate)
Control movement required
The cockpit flight control that allows the pilot to changethe pitch of angle of all the TAIL rotor blades collectively in order to provide heading control.
Yaw pedals
Yaw pedals control pitch of the tail rotor blades to: (4 answers)
Counter main rotor torque
Overcome frictional forces in the drive train during autorotation
Provide heading control in the hover
Provide yaw control (balance) in forward flight
