Aero Flashcards
1
Q
What is moment?
A
A force applied from a distance perpendicular to an axis
2
Q
What is Equilibrium?
A
When the some of all forces and all moments around the CG equals zero
3
Q
Is trim equilibrium?
A
Not necessarily, in trim the sum of all moments are equal
4
Q
What does a vector represent?
A
Magnitude and direction
5
Q
What does scalar represent?
A
Magnitude
6
Q
What is air density?
A
Air molecules within a given volume
7
Q
What does humidity do to air density?
A
It makes it decrease = less dense
8
Q
What is moment arm?
A
Perpendicular distance from the axis to the point of force
9
Q
What is atmospheric static pressure?
A
The weight of a column air over a specific area
10
Q
What is avg lapse rate in C and F
A
2 degrees C / 3,57 degrees F per 1000ft
11
Q
General gas law equation?
A
P = p R T
12
Q
Properties of steady airflow?
A
Velocity, p, pressure and temp
13
Q
The continuity equation?
A
A1 V1 = A2 V2
14
Q
Bernoullis theorim?
A
Pt = Pd + Ps
15
Q
What are the names for aerodynamic center?
A
Quarter chord, point of maximum thickness, neutral point
16
Q
What kind of pressure is under the wing?
A
Small/medium
17
Q
Ways to write dynamic pressure?
A
Pd = q = 1/2 p v^2
18
Q
Describe the different airspeeds
A
Indicated = dynamic press in pitot tube Calibrated = corrected for instrument errors Equivalent = Corrected for compressibility errors True = Actual velocity through air, corrected for p Ground = corrected for wind speed
19
Q
What is chord line?
A
A indefinite line that goes straight through leading edge stagnation point to trailing edge stagnation point
20
Q
Mean camber line?
A
Line from leading edge to trailing edge, which is halfway between upper and lower surface of airfoil
21
Q
How is camber decided?
A
Distance from MCL to chord line (curvature of airfoil)
22
Q
What is b?
A
Wingspan
23
Q
What is s?
A
Surface area of wing ( b x c)
24
Q
What is c?
A
Average chord, Average of all chords from wing root to wing tip
25
What is chord wise airflow?
Airflow which is perpendicular to leading edge, it accelerates over the wing and creates lift
26
What is spanwise flow?
Airflow perpendicular to leading edge, it goes from wing root to tip and creates drag
27
What is pitch attitude?
Angle between longitudinal axis and horizon
28
What is relative wind?
It is windflow opposite flight path
29
What is flight path?
Path of CG going through the air mass
30
What is AoA
Angle of Attack, angle between chordline and relative wind
31
Angle of incidence?
Angle between longitudinal axis and chord line
32
What is longitudinal axis?
Nose to tail, (roll)
33
What is the lateral axis?
Wingtip to wingtip, Pitch
34
Rotation around vertical axis is called?
Yaw
35
What is the CG?
The point where all weight is concentrated and all the axis intercept
36
What is the aerodynamic center?
The point where all aerodynamic forces are acting and the center of lift
37
Name the two aerodynamic forces
Lift and drag
38
Cl consists of what?
```
CArVAC:
Compressibility
Aspect ratio
Viscosity
AoA
Camber
```
39
What happens with Clmax and Clmax AoA when flaps are extended?
Clmax goes up, Clmax AoA goes down
40
What is parasite drag and the equation for it?
It is form and friction drag:
Form drag being the shape that creates a low pressure wake, therefore drag
Friction drag is interaction at the skin creating turbulent flow and therefore drag
Equation: q f
41
What can you do to prevent form and friction drag?
Form: Streamlining
Friction: Cleaning, painting, flush mounted rivots
42
What is induced drag?
Spanwise airflow create wing tip vortices and creates net downwash and reduces the vertical lift.
Created by high AoA
43
How do you prevent induced drag?
Wing tip devices: Winglets, wingtip missiles
| Ground effect: One wingspan to the ground reduces downwash and allows lift to be more vertical
44
What is the boundary layer?
A thin layer of airflow over an airfoil that consists of laminar and turbulent air flow
45
Describe laminer airflow
High kinetic energy, non sticky
46
Describe turbulent airflow
Chaotic but sticky
47
Describe the adverse pressure gradient
The point where the boundary layer separates and turns into turbulent flow, this is creates due to the high pressure air in the back of the airfoil wanting to go to the low pressure at the center of the airfoil.
48
What happens when the boundary layer separates before the Aerodynamic center?
Stall
49
Describe stall speed
Minimum airspeed required to maintain level flight at Clmax AoA
50
What is a stall?
Flight condition where an increase in AoA results in a decrease in Cl
51
Describe a power on Stall
Lower stall speed than power off due to the vertical component of thrust and increased airflow over the wings on prop planes
52
Stall recovery?
Relax
Max
Level
Ball
53
What is a spin?
Stall with a yaw
54
How is autorotation in a spin created
This is due to asymmetrical stalled wings.
The outside wing has a lower AoA, it is stalled less and creates more lift than the inside wing, which also creates more drag
55
The 4H club?
Hot, humid, heavy, high
56
Will T/O speed be affected by wind?
No, wind will have an effect on T/O distance
57
What does f stand for?
Equivalent parasite area
58
What does rate describe?
Time
59
What does angle discribe
Distance
60
What is max angle of climb?
Vx
| Max altitude while min distance
61
What is max rate of climb?
Vy
| Max altitude with min time
62
What is max cruising range?
Max distance traveled for a given amount of fuel. (L/Dmax)
63
What is max cruising endurance?
Max time in air for a given amount of fuel, lowest Fuel Flow
64
Why does higher altitude give the engine a more efficient FF?
Decreased inlet temperature
65
What is max gliding range?
Min angle of decent, L/Dmax
66
What is max glide endurance?
Min rate of decent, occurs at bottom of the power curve. least amount of power defecate.
67
What is region of reverse command?
When AoA is higher than max endurance, you have to increase thrust in order to decrease velocity
68
What are the two types of decelerating techniques?
Aerodynamic breaking
| Mechanical breaking
69
Describe aerodynamic breaking
The stick is held back after touch down to use the elevator to increase drag. Good at higher speeds, but surfaces becomes insufficient at lower speeds.
70
Describe mechanical breaking
the mechanical breakes are used. good for low speeds
71
When landing what crosswind technique should you use?
Wing into wind, top rudder (slip)
72
When taking off what kind of crosswind technique should you use?
Ailerons into wind, rudder for directional control
73
Describe a slip
Uncoordinated turn because of insufficient rudder. The nose is outside the turn, increase in range, decrease in rate. Good for safe decending
74
Describe a skid
Excessive rudder. Nose inside turn, radius decrease, rate increase. Can be cause a skidding stall
75
What is p-factor?
When the relative wind is below the thrust line, the right side of the propeller makes more thrust creating a yaw left. Seen at low speeds and high power settings
76
What is the slipstream swirl?
Cork screwing airflow goes down the fuselage and and pushes the vertical stabilizer to the right, thus creating a yaw to the left.
77
What is n?
G's, load factor
78
To maintain maintain a level turn, what must you do with lift?
The total lift must be increased to make vertical lift stay the same and oppose weight
79
What is limit load?
The max load in normal operation without any risk of permanent deformation. Exceeding this limit results in over stress. This is 2/3 of Ultimate load
80
What is ultimate load?
Max load airframe can sustain without permanent damage. This is 1.5 times the limit load
81
What is elastic limit?
Max load which can be placed on a material and it still being able to return to original state.
82
In a V-n diagram:
| What happens if you stay under the maneuvering speed?
No combination of wind, gust or maneuvering can cause overstress.
83
What make the biggest wake turbulences?
Heavy, clean and slow
84
How fast does wing tip vortices fall?
400-500 ft/min
85
What is a wind shear?
Sudden change in wind speed and direction
