Principles of Flight Flashcards
What is Newtons first law?
A body will continue in a state of rest or uniform motion unless acted upon by an external force
What is Newtons second law?
The rate of change of momentum of a body is proportional to the applied force (F=ma)
What is Newtons third law?
To every action there is an equal and opposite reaction
What is the formula for Density?
Pressure (P) / Temperature (T) x Constant (R)
What are the four forces that act on an aeroplane?
Lift
Weight
Thrust
Drag
If a plane is in straight and level flight at constant airspeed, how are the forces balanced?
Thrust = Drag
Lift = Weight
Where does lift act?
Through the centre of pressure at 90 degrees to the local airflow over the wing
Where does weight act?
Through the centre of gravity
How does increasing weight affect wing loading?
For a given area, increasing weight increases wing loading
What is the Lift equation?
Lift = CL 1/2 p V^2 S
What is the formula for Aspect Ratio?
Aspect Ratio = Wingspan/Mean Chord
How does the centre of pressure move with increasing angle of attack?
The centre of pressure moves towards the leading edge of the wing as AoA increases, until stall is reached at which point it moves quickly rearwards.
What are the two types of drag?
Parasite Drag and Induced Drag
What are the three types of parasite drag?
Form Drag - Drag created by object shape
Friction Drag - Viscosity of air against the surface
Interference Drag - Spanwise flow disturbing the smooth airflow over the aerofoil
What is Parasite Drag?
Zero Lift Drag
The drag caused by the non-aerodynamic shape of the aircraft. In other words, the resistance to our efforts to push the aeroplane through the air at high speed.
What is Induced Drag?
Aerodynamic Drag
Induced drag is the by-product of creating lift. The amount of induced drag is dependent on the amount of lift being generated. ie Wake Vortices.
What is the Zero Lift (Parasite) Drag equation?
Zero Lift Drag = Cd 1/2 p V^2 S
With respect to drag, when will the aircraft achieve maximum range?
When flown at the airspeed that creates minimum drag. Ie the bottom of the total drag curve.
What happens to the composition of gases as altitude increases and pressure decreases?
The composition (%) of gases remains constant irrespective of pressure or altitude.
As a rule of thumb what is the temperature reduction per every 1000ft?
2 Degrees
Why is an International Standard Atmosphere required?
For aircraft performance calculations.
For standard separation of commercial traffic at altitude
For expected temperatures at altitudes
As a base line to calculate forecasts from
What is Boyles Law?
At a constant temperature, the volume of gas is inversely proportional to its pressure
What is Charles Law?
The volume of a gas at constant temperature is directly proportional to its absolute temperature.
What is Henrys Law?
The amount of gas dissolved in a liquid is proportional to the gas pressure outside of the liquid.