Aerodynamics Flashcards
What is due to the weight of the air molecules in the atmosphere?
Static pressure
As air accelerates, what happens to static and dynamic pressure?
Static decreases and dynamic increases
Dynamic pressure is due to?
Relative movement
What is the formula for dynamic pressure?
1/2pvsquared
The point on the aero foil at which streamlined, laminar flow become turbulent is know as the ?
Transition point
The point on the aerofoil at which turbulent flow separates is know as the?
Separation point
A well chambers aerofoil will produce lift at 0 degrees angle of attack, true or false?
True
A symmetrical aerofoil will produce no lift at 0degrees angle of attack true or false?
True
What is the point where lift is assumed to act?
Centre of pressure
The chord line is a straight line which?
Joins the leading and trailing edge
At a high angle of attack most of the loft on an aerofoil is produced where?
Leading edge
As angle of attack is increased up to critical angle, what happens to the centre of pressure?
Moves forward
When the critical angle is exceeded, what happens to the centre of pressure?
It moves aft
Thrust stream turbulence varies with?
Engine power and distance from the source
Which flight condition of a large jet would create the most severe flight hazard by generating vortices of the greatest strength?
Heavy, slow and flaps up
What effect would a light crosswind have on the wingtip?
The upwind vortex will tend to remain on the runway longer than the downwind vortex
If you take off behind a heavy jet that has just landed, where should you plan to take off?
Beyond the point where the jet touched down
Washout refers to a design feature whereby?
The riggers angle at the wing root is greater than at the wingtip
What is the load factor in straight and level?
1
What is an indicator of a spin?
IAS low and almost unchanging
What factors affect stall speed?
Centre of gravity
Power setting
Load factor
Maximum range is achieved by flying at what speed?
The speed for minimum drag
Maximum endurance is achieved by flying at what speed?
The speed for minimum power
What is relative airflow?
Opposite to the direction of the path of the aircraft
What is the angle of attack?
Angle between the chord line and relative airflow
What is camber and what does increasing it do?
Curvature of the aerofoil
Increasing camber on upper surface will cause airflow to accelerate over it more, generating more lift at same angle of attack
When does the maximum camber occur?
The point where distance between camber line and chord line is greatest
What is couple moments?
Interaction of two moments separated by a horizontal distance
Which is stronger, lift to weight couple or thrust drag couple and what force balances them out?
LW is stronger and the horizontal stabiliser force balances them out
When the total pressure remain unchanged, what happens to local static and dynamic increases?
Static decreases
What is likely to occur while banking in climb?
Over banking due to higher speed and increased angle of attack on outer wing. Outter wing crest more lift than inner
What is likely to occur while banking in a descent?
Under banking in descent
Outter wing travels a greater distance while inner wing has greater AoA
What causes aircraft to yaw out of turn?
Increased drag on down going aileron
How do you minimise the affect of adverse aileron yaw?
Frise type ailerons
Differential ailerons
Coupling the rudder
How do fries type ailerons work?
Uses offset hinges to deflect part of the up going aileron into the air, increasing drag
How do differential ailerons work?
The up going aileron travels further up than the down going aileron, increasing drag
How does coupling ailerons and rudder work?
As ailerons are deflected, rudder automatically moves to counter act the adverse yaw
What is the load factor in a 60degrees AoB?
2g
What is the load factor formula?
Lift / weight
Which wing stalls first in a spin?
Down going wing
Why is the use of ailerons close to or in a stall incorrect?
Down going aileron increases angle of attack further, stalling the wing further
What is IAS likely to suffer from?
Pressure and instrument error
How is calibrated airspeed calculated?
Corrected IAS for pressure and instrument error
How is equivalent airspeed calculated?
Calibrated airspeed corrected for compressibility error. (CAS always higher than EAS)
How is true airspeed calculated?
Equivalent airspeed correct for density error
In order to fly a turn of same radius at higher airspeed, what do you need to do?
Fly a greater bank angle
What is the constant rate turn?
180 degrees in 1min
360 degrees in 2 min
Turn of 3 degrees per second
10% airspeed + 7 = AoB (degrees)
What two variables control turn performance?
Angle of bank
True airspeed
What affect will increasing the TAS have on the radius and rate of turn?
Increase radius of turn
Decrease rate of turn
What affect will decreasing IAS have on radius and rate of turn?
Decrease radius of turn
Increases rate of turn
What affect will increasing the angle of bank have on radius and rate of turn?
Decrease radius of turn
Increase rate of turn
What affect will decreased angle of bank have on radius and rate of turn?
Increase radius of turn, decrease rate of turn
Longitudinal stability is stability about what axis?
Lateral axis, pitching plane
Lateral stability is stability about which axis?
Longitudinal axis (rolling plane)
Directional stability is stability about which axis?
Normal axis (yawing)
Where is the restoring force for longitudinal stability?
Horizontal stabiliser (tail)
How is lateral stability increased?.
With dihedral and high wing
Sweepback wings
What provides restoring force for directional stability?
Large keel surfaces aft of CoG
What is stronger, lateral or directional stability? What is one affect of this difference?
Directional stability
Spiral dive
What is the function of the trim wheel?
Reduce the moment of the hinge line of the control surfaces to zero (hands off)
Where can trim tabs be located?
Elevator
Rudder
Aileron
What and why are balance tabs used for?
Reduce the force required to deflect control surface. Used as planes get faster and control surfaces get bigger
What are the types of balance tabs?
Fixed
Aerodynamic
Automatic
What are fixed balance tabs?
Small metal tab that can be bent into set position.
Only adjusted on the ground, need to be confirmed by flight test
What are Aerodynamic balance tabs?
Most commonly used in rudders and elevators
Horn balance protrudes into airflow
What are automatic balance tabs?
Tab is lined with control surface and automatically moves to assist control deflection.
Tab moves opposite direction to control surface to provide assisting force.
What is mass balance?
Helps reduce flutter by moving CoG closer to hinge line
When taxing into strong headwind, what should you do?
Control column either neutral or back
When taxing with a strong tail, what should you do?
Hold control column forward
