PPL training lessons Flashcards
Name all the aerodynamic forces acting on an aircraft
Thrust, drag
lift, weight
What is lift
The upwards force acting on an aircraft, it is caused by relative wind and the wing design
What is weight
The combined load of the aircraft itself, fuel, baggage cargo or anything onboard the aircraft. Weight opposes lift and acts vertically downwards through the aircraft’s center of gravity.
When are weight and lift equal
In steady unaccelerated flight
What is thrust
A forward moving force. In order for an aircraft to move forward, it must first overcome drag
What are the two types of drag
Parasite drag
-form drag
(air going around the shape of the aircraft)
-interference drag
(when different streams of airflow interfere with each other creating little pockets of turbulence)
-skin friction drag
(Drag caused by the surface of the aircraft)
Induced drag
(drag that is created as a direct result of lift)
What is the lift to drag ratio
The optimum speed where an aircraft can achieve the least possible amount of drag
When are thrust and drag equal
In steady unaccelerated flight
What is stall
A condition in which the lift suddenly decreases and the drag suddenly increases
When will an aircraft not stall
As long as lift is more powerful than weight, the airplane will still fly
How does the angle of attack affect stall
If we increase the angle of attack, there will come a time where the lift produced can no longer support the weight, there will be a stall.
If the angle of attack goes beyond the critical, it will stall
Each airplane has a specific angle of attack at which it stalls at. What affects the speed at which the aircraft stalls at?
Altitude and gross weight affect the speed at which an aircraft stalls at, but the angle of attack will be the same
what is the critical angle of attack
The optimum angle of attack before an airplane stalls at
What is spin
An aggravated stall where yaw is introduced which causes a downwards corkscrew path
What is spin (talk in terms of the wings)?
When an aircraft stalls, it is possible for one wing to stall more than the other, causing an aggravated stall leading to a spin
What is uncoordinated flight (what is it also known as)
Any time the vertical axis of the aircraft is not aligned with the direction of travel. It is also known as a side slip
What is stability
Stability is the ability of an aircraft to correct for disturbances in its equilibrium and return to its original flight path.
Most aircraft’s are designed with what inn mind?
Stability
The less stable an aircraft the more what is it?
More manauverable it is, like fighter jets
What are the two types of stability
Static
-initial tendency of the aircraft after the equilibrium is disturbed
(what your airplane’s immediate reaction is after you make a control input)
There can be positive neutral and negative static stability
-dynamic
The airplanes response to an upset in the equilibrium over time
There is an positive negative and neutral dynamic stability
What is positive static stability
If your airplane pitches up then goes back to its original.
So there’s a change in the equilibrium but that is fixed and it goes back to normal
What is neutral static stability
If you pitch the airplane up and it continues at that exact angle.
What is negative static stability
If you pitch the airplane up at an angle and it goes beyond that angle (it is undesirable)
Explain neutral dynamic stability
If the oscillations stayed the same over time after a disturbance in the equilibrium
Explain negative dynamic stability
If the oscillations get bigger over time
What is controllability
How well the airplane responds to your control inputs
If stability decreases, what happens to controlability
Controllability also decreases
Give me 3 ways in which we affect controllability on an aircraft
By moving its centre of gravity
We can also change the AoA
Or by making power changes
What causes the centre of lift to move back
When you increase the speed of your airplane and reduce the angle of attack, the centre of lift will move backwards.
What can make an airplane become more stable
An increase in distance between your centre of gravity and your centre of lift
What are three ways the plane moves (axis)
-lateral axis (longitudinal movements on pitch axis)
-longitudinal axis (roll axis)
-vertical axis (yaw axis)
Describe the plane moving on its lateral axis
This is when the airplane pitches up and down and moves longitudinally
Describe the plane moving on its longitudinal axis
In the longitudinal axis the plane moves laterally
Describe the plane moving on its vertical axis
This is where we get our sideways movement
How do we create movements on the lateral axis
Movements on the lateral axis are made by using the elevator.
We use the yoke to make this control input.
Explain what makes the airplane turn?
We turn the airplane by banking it on the longitudinal axis.
We do this by rotating the yoke right or left.
When we rotate the yoke to the left it raises the left aileron and lowers the right aileron. The lowered aileron will create more lift and will cause that wing to rise thus will then cause the plane to rotate to the left.
how do airplanes fly
The engine is responsible for creating a force called thrust, which will make the airplane move forward.
Thrust varies on the type of engine
As the airplane accelerates during takeoff air begins flowing over the wings due to the way that the wing is shaped.
The air flowing above the wing gets accelerated which then creates a low pressure area.
High level pressure wants to go to low pressure so the wing creates a force called lift which opposes gravity and causes the plane to fly
Why do airplanes need flaps
They increase lift and drag because of this we can land at slower airspeeds which is safer and easier
When we don’t need them we can raise them and cruise at higher airspeeds
