M8 Flashcards
How is static pressure denoted?
Letter P
How is Dynamic pressure denoted?
Letter q
What direction does static pressures travel in?
All directions
What direction does dynamic pressure travel in?
Direction of flow?
What is the temperature at sea level?
15 degrees 288 Kelvin
How is speed of sound denoted?
Letter a
What is the density at sea level?
1.225 kg/m cubed
What is the equation for speed of sound?
A = 20 square root of temperature
What is the pressure at sea level?
1013.25
What is the subsonic region?
Travelling below the speed of sound and the region up until Mcrit
Where will the pressure waves be when travelling in the subsonic region?
Around the aircraft
What is the transonic region?
Region between Mcrit and up to Mach 1.3. Will be travelling at the speed of sound
Where are the pressure waves when travelling in the transonic region?
Shockwave starts to form as pressure wave cannot escape the front of the aircraft
What is Mcrit?
The maximum speed at which an aircraft can travel before forming a shockwave
What is the supersonic region
Travelling faster then the speed of sound, Mach number is larger then 1.3
Where are the pressure waves when travelling in the supersonic region?
Behind the aircraft?
What is the equation for dynamic pressure?
q = 0.5 x Rho x V squared
What is a property of air in the subsonic region?
Incompressible
How does a jet outlet work
Diameter decreases and speed increases
How does the diffuser outlet work?
Diameter increases and speed decreases
What is the stagnation point?
Point on the leading edge where dynamic pressure is = 0 and static pressure is = total pressure
Explain the continuity equation
Speed of airflow is inversely proportional to cross sectional area of the tube as long as the diameter remains constant
How do you work out the Mach number?
Speed of aircraft / speed of sound
What is up wash?
Streamlines pass the upper surface of the aerofoil
What is down wash?
Streamlines on the upper surface on the trailing edge flow downwards of the aerofoil
What is the Magnus effect?
Cylindrical rotation which causes an increase of local speed above the win and a decrease of local speed below the wing
What is a general rule about vortices?
They always form in pairs and rotate anti clockwise
Where is the max camber of a low speed profile found?
5% of chord line and 45% aft of leading edge
Where is the max thickness of a low speed profile found?
18% of chord line and 30% aft of leading edge?
How do you determine the angle of incidence?
Chord line of profile and longitudinal axis of the aircraft
How is the angle of incidence denoted?
Gamma
How is the angle of attack determined?
Angle between the chord and the direction of wind
How do you work out wing area?
Wing span x average chord
How is taper ratio found?
CR / CT
What is aspect ratio?
Wing span / average chord
What type of a/c has a high aspect ratio?
Gliders
What type of a/c have a low aspect ratio?
Fighter jets
If there is a higher aspect ratio then what is there less off?
Induced drag