2021 General Knowledge Flashcards
What is the chord line?
The straights line joining leading edge to the trailing edge.
What is the camber line?
Line which runs midway between the upper and lower surfaces of the wing and curves with the wing.
What is angle of attack?
Angle between the chord and the relative airflow.
What is aspect ratio?
It is the ratio of the wingspan to the wing chord. i.e. a glider would have a large aspect ratio.
What is the angle of incidence?
Angle between the longitudinal axis and the chord line.
Angle of INDUSTRY.
What is the lift formula?
Lift = ½ ✕ ρ ✕ V² ✕ S ✕ Cₗ
ρ = air density V = true airspeed S = surface area of wing Cₗ = coefficient of lift
What is form drag?
Result of air moving over a particular shape like an aircraft’s fixed landing gear.
What is skin friction?
The friction felt by the air when it moves over all surfaces of an aircraft.
What is interference drag?
Drag that results from two or more objects that are joined together; such as the fuselage and the wing.
What is induced drag?
A by product of producing lift; Newton’s 3rd Law.
Does induced drag increase or decrease with speed?
Induced drag is highest at low speeds and lowest at high speeds.
Does induced drag increase or decrease with weight?
Induced drag increases with weight for a given speed.
Does induced drag increase or decrease with altitude?
Induced drag increases with altitude.
What are the three components that make up parasite drag?
Skin friction, form drag & interference drag.
Does parasite drag increase or decrease with speed?
Parasite drag is lowest at low speeds and highest at high speeds.
Does parasite drag increase or decrease with weight?
Remains unchanged.
Does parasite drag increase or decrease with altitude?
Parasite drag decreases with altitude because of reduced air density.
What does weight act through, centre of gravity or centre or pressure?
Centre of gravity.
What does lift act through, centre of gravity or centre or pressure?
Centre of pressure.
In regards to stability of an aircraft, how should the centre of pressure and centre of gravity be aligned with each other?
The centre of gravity must always be ahead of the centre of pressure.
What is flight for maximum range?
Maximizing the distance flown per unit of fuel burnt.
Maximum speed for power (fuel).
What is flight for maximum endurance?
Maximizing the time airborne per unit of fuel burnt.
Lowest power setting for fuel flow
Define the service ceiling:
When an airplane reaches a height where a maximum rate of climb reduces to 100 feet per minute.
Define absolute ceiling:
When an airplane reaches a height where the rate of climb reduces to zero.
What happens to your aircraft during a stall?
Centre of pressure
As the angle of attack of a wing is increased, the centre of pressure of the wing will move forward. When the wing stalls, the centre of pressure rapidly moves backwards.
In conventional aircraft, where are the stalling speeds on the airspeed indicator?
Beginning of the white arc (flaps fully extended) and beginning of the green arc (flaps fully retracted).
What attributes to change in angle of attack in straight-and-level flight and in turn can change the stall speed?
- Weight
- Centre of Gravity
- Load factor (over 1)
- Configuration changes
What is load factor?
The ratio of lift to weight. It is measured in G’s.
Lift/weight = load factor
What is the load factor in straight-and-level flight?
1.
How do you calculate load factor in a bank?
1 / cos(θ) = lift
lift / weight = load factor in G’s
How do you calculate stalling speed in a bank?
stalling speed = √(1 / cos(θ))
How do you calculate the required angle of bank for a rate 1 turn:
True airspeed / 10 + 7
What is aircraft stability?
Refers to the ability of an aircraft to recover from a disturbance about a particular axis.
What is static stability?
The initial response to a disturbance.
What is dynamic stability?
The behavior of the airplane following the static response.
Three basic types: neutral, stable, unstable.
What is stability about the lateral axis?
Longitudinal or pitch stability.
What is stability about the longitudinal axis?
Lateral or roll stability.
What is stability about the vertical axis?
Directional or yaw stability.
Do servo tabs operate in the same or opposite direction of the main control surface?
Deflects in opposite direction.
Does an anti-servo tab deflect in the same or opposite direction to the main control surface?
Deflects in same direction.
Do balance tabs deflect in the same or opposite direction to the main control surface?
Deflects in the opposite direction.
What are the 4 principles of the four-stroke engine?
Intake, compression, power, exhaust
Suck, squeeze, bang, blow
What is valve overlap?
The portion of the four-stroke cycle which both valves are open (intake and exhaust).
What can cause detonation:
- Using fuel with too low an octane
- Running the engine too hot
- Running the engine with too high a manifold pressure for the rpm
What colour is AVGAS 80/87?
Red.
What colour is AVGAS 100/130?
Green.
What colour is AVGAS 100LL?
Blue.
What colour is aviation turbine fuels?
Straw/clear.
What colour is MOGAS 87-90?
Green.
What colour is MOGAS 84-87?
Undyed/no colour.
What are the 4 uses of oil?
Lubrication, cooling, flushing, sealing.
What is normally aspirated?
The air taken into the inlet manifold at atmospheric pressure and is not compressed before being routed to the engine.
What is turbocharged?
The air taken through the inlet manifold is increased to above sea level pressures by means of a compressor before being routed to the engine.
Compressor is driven by the turbine, which is driven from exhaust and waste gases!
What is turbonormalized?
Similar to a turbocharged engine, except that the pressure is normalized to to sea level pressure, no more, no less.
What is supercharged?
The air taken through the inlet manifold is increased to above sea level pressures by means of a compressor before being routed to the engine.
Engine driven!
What is critical altitude?
The altitude at which the turbocharger can no longer maintain pressure in the inlet manifold required for the engine to develop rated power. Power/performance will decrease to a normally aspirated engine.
What is a wastegate?
It controls the amount of exhaust gas that passes through the turbine of a turbocharger and how much bypass the turbine goes directly into exhaust.
Wastegate open = bypasses the turbine and exits through exhaust
Wastegate closed = exhaust gasses are sent to the turbine & compressor; “fully turbocharged”.
How is energy extracted from a piston engine versus a jet engine?
In a piston engine, energy is extracted when the cylinder head is forced downwards by the combusting gasses.
In a jet engine, the energy is extracted by the turbine.
Gas turbine engine components:
Inlet, compressor, combustion chamber, turbine section and exhaust.
What are the two main types of compressors in jet engines?
Axial compressor and centrifugal compressor.
What are the three types of combustion chambers?
- Can type
- Annular type
- Can-annular type
What is the correct fuel to air ratio in a turbine engine?
15:1.
In a typical gas turbine engine, how much energy does it extract from the combusted gas stream?
About 75%.
What is engine pressure ratio (EPR)?
Ratio of the total pressure of the exhaust stream to the total pressure of the inlet air.
Comparing the BEGINNING and the END components of a turbine engine!
What is N1?
Speed of the low pressure compressor and low pressure turbine. Measured using a magnetic pickup on the low pressure shaft.
What is N2?
Speed of the HIGH pressure compressor and the HIGH pressure turbine.
Usually not used in turbojet or turbofan engines.
Formula for thrust:
Thrust = mass flow through engine ✕ change in speed through engine
Kinetic energy formula:
Kinetic energy = ½ ✕ mass ✕ V²
What is the weight shift formula?
Total weight to be shifted / Total weight
=
Change in CG / Change in arm
Two general types of turboprops:
Direct drive & free turbine type.
Describe propellers:
Simply rotating wings. Lift that the propeller generates is thrust and the drag felt by the engine is torque or resistance of propeller rotation.
`How can a propeller get the most thrust with the least torque?
Must fly at its maximum lift to drag ratio.
How does the airspeed indicator actually measure its airspeed?
Dynamic pressure = Total pressure (dynamic + static) - static
Pitot tube and static port respectively!
What is indicated, calibrated and true?
Indicated is what is shown on the airspeed indicator
Calibrated is indicated corrected for position error and instrument error
True is airspeed corrected for temperature and pressure
What do pitot-static and static instruments rely on?
Static (atmospheric) pressure for their operation.
However, the airspeed indicator relies on both the static pressure and the dynamic pressure on the pitot tube.
How does the ignition system in a turbine engine differ from a piston engine?
Turbine engines: Ignition only for start & precipitation (heavy rain or ice)
Piston engine: Starter operates continuously
How does an anti-servo tab work?
Aids the pilot by applying a force in the SAME direction than the control is moved.
Servo Tab: opposite direction
Balance tab: opposite direction
Anti-Servo tab: same direction
How much available energy produced in the combustion chamber on a turbojet engine is required to drive the compressor?
85%
Why are fuel injected engines less susceptible to icing?
Fuel is sprayed in the inlet manifold where it is warm.
What does a truss-type construction consist of?
- Longerons
- “N” girder
- Warren truss
What does a monocoque construction consist of?
- Formers
- Stringers
- Stressed skin
When does mach buffet occur?
When going transonic, aircraft begins to have characteristics like a slow-speed stall
How can you achieve max range in a piston driven engine?
Fly at a speed for best lift to weight ratio.
What point to the lateral, vertical and longitudinal axis pass through?
Centre of gravity.
What relationship does Va have with weight?
Va will remain constant or increase with weight
What can a VORTAC emit?
VOR and DME.
Don’t go too technical with this!
What does a critical surface mean when referring to the “clean aircraft concept”?
Wings, control surfaces, propellers, horizontal stabs, vertical stabs, any other stabilizers, upper side of fuselage.
Basically all surfaces, DO NOT get technical with antennas, etc.
How many dimensions of control can you find on a typical modern autopilot?
Roll, pitch, yaw, altitude, latitude, longitude.
6.
What does the top end of the white arc represent?
Vfe.
What is somatogravic illusion?
Usually felt during moments of acceleration (Like take-off) where it creates an illusion of pitching up.
Pitching up could cause a stall.
What are the 5 hazardous attitudes (IM SAFE)?
Resignation Anti-authority Machismo Impulsivity Invulnerability
“RAMII” gallard
Describe hypoxic hypoxia:
Insufficient oxygen at PRESSURE available in lungs.
HELIOS
Describe stagnant hypoxia:
Blood and oxygen is prevented from MOVING throughout the body.
Felt when pilots are “stagnant” for a while.
Describe Anemic hypoxia:
Blood is unable to absorb and carry oxygen from the lungs to the body.
“Anemia” means a lack of red blood cells. You lack blood capabilities. (Blood vs Oxygen)
Describe hystoxic hypoxia:
Cells and organs are unable to absorb oxygen properly.
Hystoxic means your body is refusing to absorb oxygen. (Body vs Oxygen)
Why does applying carb heat in a fixed-pitch propeller result in a drop in RPM?
The mixture is richer & hot air is less dense than cold air
Difference between a piston and turbine engine igntion?
jj
What is a characteristic of a fixed spool engine?
Compressor turbine and power turbine are on separate shafts.
What effect does haze on final approach give? (Illusion)
Runway appears further away, tendency to fly high on the approach
How does a turbocharger work?
Increases the MASS of the air which supplies the engine thus increasing the power output of the engine.
An NDB operates in:
The low or medium frequency bands; not restricted by line of sight.
DME operates in the:
UHF range.
What happens to the coefficient of list as your altitude increases?
It remains the same.
What is a rate 1 turn?
When the turning rate is 2 degrees per second.
1 minute to complete a 180, 2 minutes to complete a 360.
In order for an aircraft to be longitudinally stable:
Centre of gravity should ALWAYS be ahead of the centre of pressure.
What oil do we use in the winter time?
Less viscosity, SAE 40 or 30
What oil do we use in the summer time?
Higher viscosity, SAE 60
What two units are used for an engine manifold pressure gauge?
Engine RPM and outside air temperature dictate the readings in the manifold pressure gauge.
What is ground loop?
Excessive yawing on the ground, most commonly happen on taildraggers & results when the plane spins on the ground.
“Rotation of a fixed-wing aircraft in the horizontal plane while on the ground”
How does the airflow under the wing flow?
Airflow flows OUTWARDS on the under side of the wing.
How does the airflow over the wing flow?
Airflow flows INWARDS on the top side of the wing.
What does sweepback contribute to?
Directional stability.
What is different about a diesel engine?
The fuel is added AFTER the air is compressed; versus in a gas engine, the fuel/air mass is compressed and ignited.
What are the airspeed indicator errors?
- Density error
- Position error
- Lag error
- Icing error
- Water error
How do you calculate maximum crosswind for an aircraft given stalling speed?
Take 20% of the aircrafts stalling speed.
This will equal the maximum crosswind component.
Carburetor fuel to air ratio is governed by:
WEIGHT.
Carburetor is old & fat; weight.
As angle of attack increases ______ and induced drag ________.
Increases and increases.
What is the fuel to air ratio for best power?
1 part of fuel to 14 parts air.
What is the first sign of carburetor icing?
RPM or manifold pressure decrease.
When does P-factor occur?
Only in a climb, for multi-engine airplanes.
What is effective propeller pitch?
The actual distance a prop moves forward in one revolution while flying.
When an ammeter is overcharging, what could be the problem?
The voltage regulator has failed.
As the angle of attack of a wing increases the lift increases,
Induced drag increases.
Some aircraft have a maximum zero fuel weight limitation because:
By having fuel in the wings which eliminates fuselage bending stress.
Gliding distance when facing a headwind can be increased by:
Increasing airspeed.
What is hyperventilation?
The rate at which we breathe is NOT regulated by the amount of oxygen in the lungs, but the amount of carbon dioxide in the lungs.
Hyperventilation will NOT increase the oxygen in the lungs, but it will push out the carbon dioxide. However it constricts blood vessels & stops blood flow to brain.
What does hypoxia and hyperventilation have in common?
Both cause a reduction of oxygen delivery to the brain.
What are symptoms of hyperventilation?
Lightheadedness, numbness around mouth, tingling of fingers.
What are the sensory illusions?
- Kinesthetic illusions
- Visual illusions
- Vestibular illusions
What is a kinesthetic illusion?
This is when a pilot in IMC conditions is flying by the “feeling” of the plane, which is VERY dangerous. (SUBCONSCIOUS FLYING)
What is a visual illusion?
2 types: central vision illusions and peripheral illusions.
Central illusions: misunderstanding in what we see; or an expectation
(runway illusions, false horizon, autokinesis)
Peripheral illusions: false impressions of surrounding conditions; much like kinesthetic illusions.
(black-hole effect, pitch up illusion, vectional illusion)
What is a vestibular illusion?
A false sense due to fluid moving in the ear canal (VESTIBULAR = ear system)
Acceleration & deceleration illusion, false sense of turning)
