Test Prep Flashcards

Question

Load Factors during manouvers Formulas

Answer 1

For Pull-Up/ Flare manouver: 𝑛_𝑧 = (𝐿₀ + Δ𝐿_𝑚𝑎𝑛)/𝑤 For Steady Turning Manouver: 𝑛_{𝑧 = (𝑤/cos(𝜙)) ⁄ 𝑤}

Answer 2

𝑉_𝐸𝐴𝑆 = √(𝜌_𝐻/𝜌₀ )* 𝑉_𝑇𝐴𝑆

Answer 3

True Airspeed = V_CAS adjusted fo derivationds from standard atmosphere conditions (pressure and temp)

Answer 4

Indicated Airspeed = The airspeed indicated on instrument panel. Uncorrected airspeed relative to the surrounding air

Answer 5

Calibrated Airspeed = V_IAS adjusted for installation, positioning and instrumentation errors (e.g. angle of attack, sideslip angles, or flaps and landing gear settings)

Answer 6

Equivalent Airspeed: Used for structural calculations, normally converting the True Airspeed at the aircraft height into an equivalent airspeed at sea level.

Answer 7

𝑇/𝑇𝑖 = (𝑉/𝑉_𝑖) ^𝑛_𝑉( 𝜌/𝜌_𝑖)^𝑛_𝜌 Where n_𝜌 is the dependency of the thrust on the density (altituda) and n_v depends solely on the engine type.

Answer 8

TSFC = 𝑚̇_{𝑓𝑢𝑒𝑙}/𝑇

Answer 9

PSFC = 𝑚̇_{𝑓𝑢𝑒𝑙}/P

Answer 10

𝑆𝐸𝑃 = ((𝑇 cos(𝛼 + 𝜎) − 𝐷) / 𝑚 𝑔) 𝑉

Answer 11

𝑑𝑤 = −𝑚̇_{𝑓𝑢𝑒𝑙} 𝑔 𝑑𝑡

Answer 12

Δ𝑡 = ((𝑉^𝑛_𝑉) / (𝑔 𝑆𝐹𝐶_𝑥)) (𝐶𝐿 / 𝐶𝐷)_𝑥 ln(𝑤_𝑖/𝑤_𝑖+1) During Flight Fase "x"

Answer 13

Δs = ((𝑉^𝑛_𝑉+1) / (𝑔 𝑆𝐹𝐶_𝑥)) (𝐶𝐿 / 𝐶𝐷)_𝑥 ln(𝑤_𝑖/𝑤_𝑖+1) During Flight Fase "x"

Answer 14

For Turbojet/turbofan: SFC_x = TSFC_x; n_v ≈ 0 For Turboprop: SFC_x = PSFC_x; n_v ≈ -1

Answer 15

Thrust to Weight = T/w, Usually indicates the aircraft's performance, high T/w ratio is usually an indication that the aircraft is highly efficient (usually related to endurance, range, etc.)

Answer 16

Wing Loading = w/S = Weight/Surface. Indicates Stalling speed of an aircraft. A low wing loading means low stalling speed, which means take off and landing at lower speeds (or with more load), and faster turning rate.

Answer 17

𝐶𝐿 = 𝐶_{𝐿(𝛼=0°)} + 𝐶_𝐿𝛼 𝛼

Answer 18

q^-= rho/2 x V²

Answer 19

a = 295 m/s T = -57 °C = 216.15 K Constant

Answer 20

-CFD (Computational Fluid Dynamics) : Relatively good quality data, and a lot cheaper than wind tunnel testing. -Empirical: Bad quality data, not accurate -Wind tunnel testing: Good data, but expensive, can have some size limitations. -Flight tests: Can be dangerous and expensive, but can provide some of the best data.

Answer 21

-Conceptual Design : Cost goals, technology, Estimated L and D., Weight goals, Airfoil Design -Preliminary Design : Design freeze, External Configuration, Camber and Twist, Loads, Stresses. -Detail Design : Construction of individual parts, Manufacturing Process, Assembly line, Design Optimization

Answer 22

Incidence angle

Answer 23

Geometric twist of the wing. (e.g. higher angle of attack at root)

Answer 24

The Dihedral Angle of the wing, angle between root chord and tip chord of the wing.

Answer 25

Relative thickness. Max. Thickness to chord ratio

Answer 26

Boeing has a higher Area. The leading edge imaginary line continues until it coincides with the other wings leading edge line at the middle of the aircraft. However, airbus defines its wing area differently. The leading edge does not continue, and the imaginary line between root leading edges of the wings are connected by a single straight line between them?

Answer 27

The Pressure coefficient. Defined by: C_p = (p - p_∞)/q_∞

Answer 28

Flow around wing tips. Interference between components.

Answer 29

+ : Coefficient of induced Drag - : Wing root stress for area, Necessary span at wing cord, Turbulence sensitivity.

Answer 30

+ : Manufacturing cost, Tip stall, Available fuel volume. - : Wing root Stress

Answer 31

In order to delay critical conditions, such as c_{p_crit} at higher Mach numbers,

Answer 32

A basic theory used to calculate C_L𝛼 for AR>4 and M<= 0.8 (incompressible flow)

Answer 33

Calculating C_L𝛼, but more complete than lifting line. Used for AR>2 and Mcrit (Allows compressible flow) 𝛽 = sqrt(1-M²) Which represents the compressibility effect.

Answer 34

k²: Airfoil/Pressure influence k² = 1+1.5(t/c) for 3%<(t/c)<8% k² = 1+0.75(t/c) for 8%<(t/c)<12% 𝛽 = sqrt(1-M²) Which represents the compressibility effect.

Answer 35

Calculating C_L𝛼 used only for AR<2 at any M

Answer 36

-Zero Lift Drag: Skin Friction Drag, Pressure Drag (Interference, Form Drag). -Lift-dependent Drag: Induced Drag, Lift dependent Form-Drag.

Answer 37

It describes fluid flow. It describes the flow conditions around the aircraft.

Answer 38

Always the one that is lower. So both must be calculated and if Re_co< Re, then Re_co is to be used,

Answer 39

It is each component's Form Factor. Depends on Geometry.

Answer 40

Drag produced at aircraft joints (wing-fus, fus-nac, etc). It can be estimated by counting the number of interference points. This number is basically the percentage of total drag that is due to interference drag.

Answer 41

Drag that is produced by supersonic regions on the aircraft, which in turn produce flow separation that reduces Lift.

Answer 42

Because the wing is Finite and 3 dimensional.

Answer 43

For small values of C_L (C_LL,PB): use k = 1/(𝜋 𝐴𝑅 𝑒) For Large C_L (C_{L>C_L,max)
use k = 1/(C_𝐿𝛼)}

Answer 44

Oswald Efficiency Factor. Depends on type of aircraft.

Answer 45

At C_L vs C_D curve, draw line tangent to the curve that crosses the point (0,0), where this straight line touches the curve is the max C_L/C_D

Answer 46

for a NACA 0123: -the 0 represents the maximum camber in % (0% in this case) -1 is the rel location of maximum camber (in this case 10% to the rear) -2 and 3 represent the relative thickness in % (23% in this case)

Answer 47

The point at which supersonic flow regions are formed, also called supercritical flight region.

Answer 48

It gets lower, which is bad because it means it is easier to reach. (Flow separation can happen at lower speeds)

Answer 49

+ Higher C_L,max, higher C_𝐿𝛼, higher C_L0 - Higher C_D,min, Higher C_D0

Answer 50

Camper flap (plain flap, slotted flap), Spread flaps (split flap, zap-flap), Junkers flap, Fowler System.

Answer 51

Slotted, Slat, Droop Nose, Krüger

Answer 52

Internally/Extranally blown flaps (IBF / EBF), Upper Surface Blowing (USB), Jet Flaps, etc.

Answer 53

- Reduction of total wetted area to Wing Ratio (Reduce Fuselage) - Increase of AR - Streamlining (Removing external components) - Laminarization (Remove boundary layer) - Reduction of Turbulence (Material structures in paint can reduce turbulence) - Wing Tip Forms (Winglet)

Answer 54

The neutral point should be BEHIND the center of gravity

Answer 55

Point at which the sum of pitching moments do not depend on the angle of attack

Answer 56

The adjustment of control surfaces (mostly the elevator) to keep the aircraft at a neutral position through balancing the moments.

Answer 57

The Horizontal Tail Deflection

Answer 58

Yaw Moment Coefficient

Answer 59

Design Dive Speed

Answer 60

Torenbeek, it is much simpler and gives a good approximation.

Answer 61

Landing Gear

Answer 62

m_OE = m_TO (1- C_fuel) - m_PL where C_fuel = m_fuel/m_TO

Answer 63

Structural Loads Vertical Loads (includes Limit Loads and Ultimate Loads) Maneuver Loads Gust Loads

Answer 64

Point Forces (Landing gear loads, engine thrust) Surface Forces (Aerodynamic loads, pressure differences) Body Forces (Mass inertia, gyroscopic torque)

Answer 65

Elevator Deflection Deflection of high-lift devices Vertical wind gusts Horizontal wind gusts

Answer 66

Limit Loads are expected during normal flight operation, while ultimate loads are to be reached at exceptional cases, and must be sustainable for 3 second without structural failure.

Answer 67

Vertical load factor, given by n_z = L/w

Answer 68

In the Positive load factor: -V_S+ (Stall speed at a load of 1.0g) -V_A (Design maneuvering speed), point at which the C_L,max speed and the 2.5 g upper load limit connect. -upper load limit of 2.5g -V_D (Design Dive Speed) (Max speed) In the Negative Load Factor: -V_S- (Stall speed at a load of -1.0g) -Lower load limit of -1.0g -V_C (Design Cruise speed) -V_D (Design Dive Speed) (Max speed)

Answer 69

The V-n Diagram includes V_S,flap (The Stall speed at 1.0g with extended flaps), a C_L,max curve with extended flaps, and a V_B (Design gust speed) which is the point at which the aircraft must withstand a higher load factor than the limit of 2.5g

Answer 70

1.- Draw line following the loading chart grid, which crosses the point at which the extra load is. 2.- Draw a parallel line crossing through the initial point (Center of gravity vs Weight). 3.-Draw line crossing the new weight of the aircraft from the parallel line drawn previously. 4.-From the point where these two lines cross, draw a line following the grid to the % of croot. 5.- This croot is the new position of the center of gravity

Answer 71

-Turbojet : Intake, compressor, combustion chamber, turbine, thrust nozzle. (No fan or propeller) -Turbofan: Turbojet + Fan/low pressure compressor + low pressure turbine -Turboprop: Turbojet + propeller + reduction gear -Turbo-shaft: Turbojet + propeller + reduction gear + NO thrust nozzle

Answer 72

-Gross Thrust (Outflowing mass thrust) -Net Thrust Gross Thrust - inlet Ram drag) -Installed Net Thrust (Net Thrust - Installation loss - Additional drag) -Stati Thrust (Thrust of uninstalled engine at ISA day)

Answer 73

Thrust Specific Fuel Consumption. Amount of fuel consumed per unit of thrust generated.

Answer 74

Specific Excess Power. The amount of extra energy that can be used for acceleration or climb at a given point in time.

Answer 75

Specific Energy

Answer 76

Sustained Turn Rate. Turn rate that can be maintained for a long period of time without causing excessive stress on the structure. Attained Turn Rate. Maximum possible rate of turn for a brief period of time without exceeding structural or aerodynamic limitations.

Answer 77

Describes the aircraft acceleration on the ground from standstill, until clearing a certain obstacle height. Acceleration, Rotation, Transition,

Answer 78

Drag created by the rolling resistance of an aircraft's wheels when it is in motion on the ground. Significant for Fuel Consumption and take-off performance,

Answer 79

Distance it takes for the aircraft to rotate from its fixed angle of attack during roll, to the take-off angle of attack at approximately constant speed. Moment at which the aircraft's nose wheel lifts off the ground.

Answer 80

The distance between Lift-off and where the aircraft reaches the "screen height" (clearance distance), adjusting pitch angle to achieve a certain climb rate and airspeed.

Answer 81

Flight condition at which the aircraft travels the longest time, therefore it is the flight condition at which aerodynamics must be optimized, and fuel usage must be taken into account.

Answer 82

1.- Cruise Climb: Constant Speed, Constant Lift Coefficient, BUT a changing Air Density (Height). 2.- Trimming: Constant Speed, Constant Height, BUT Changing Lift Coefficient. 3.- Throttle Back: Constant Lift Coefficient, Constant Height, BUT changing Speed (Not used)

Answer 83

#1 Cruise Climb, as it provides the maximum aerodynamic efficiency and a constant velocity.

Answer 84

For the Loiter step of the flight mission. It maximizes the time that the aircraft can be flying.

Answer 85

Engine Start-up W₁₀ = 99% Taxi W₂₁ = 99% Take-off W₃₂ = 99.5% Climb W₄₃ = 98% Cruise W₅₄ = Range equation Descent W₆₅ = 99% Loiter W₇₆ = Duration equation Landing, taxi, shut-down W₈₇ = 99.2%

Answer 86

It shows how the available payload decreases with an increase in payload and vice-versa. It tells what range is possible for a certain range, but also how much fuel is needed.

Answer 87

Its the Approach distance + the Landing Roll distance. Distance it takes the aircraft to go from loiter conditions to a complete stop on the runway.

Answer 88

W/S Weight of the aircraft divided by the total wing area. T/W Total thrust generated by the engines divided by the weight of the aircraft.

Answer 89

It is graphical representation of design limits of an aircraft which depend on the T/W ratio and Wing Loading. It establishes a feasible design region.

Answer 90

Take-off distance limit Landing distance limit Sustained Turn Rate maneuvering limit (these state performance requirements) Attained Turn Rate maneuvering limit Gust Load factor limit Specific Excess Power limit Maximum Mach number limit Minimum Speed

Answer 91

-Always Include Safety Margin for design changes -The more to the right, the smaller the wing area -The more to the bottom the smaller required thrust - Priority 1: Low Engine Weight, Priority 2: Lowest Reasonable Wing area - Caution with C_L variations along the curves. Make sure the High lift systems are able to provide this.

Answer 92

* Under the wing: +Best for maintainability, +low cabin noise, + no intake interference, - risk of Foreign Object damage, - Landing gear must be taller. * Over the wing: - Bad maintainability, - High Cabin Noise, - Moderate Intake interference, ++ Low risk of foreign object damage, + Low landing gear. * Aft-fuselage mount: - Bad maintainability, - Very low cabin noise, - High intake interference, + Low risk of foreign object damage, + Low landing gear. * Tail: - Bad maintainability, - low cabin noise, + Low risk of foreign object damage, + Low landing gear.

Answer 93

*T-Tail: +Short vertical tail, Less downwash, possible powerplant at rear, Low interference drag. - Heavy tail structure, Difficult horizontal tail, Trimmable horizontal stabilizer integration problematic, deep stall risk. *Twin-Tail: +Short horizontal tail, 2 smaller vertical tails, low blanketing-effect. - Heavy tail structure, High interference Drag, Mechanically complex vertical tail control system. Conventional Tail: +Light structure, Vertical tail easily adapted, Easy trimmable horizontal stabilizer, Simple structural transmission of tail loads. - Increased downwash, Powerplant at rear not possible, Large vertical tail, Degraded spin properties due to blanketing-effect. Cruciform Tail: + Powerplant at rear possible, Lighter than T-Tail, Less downwash than conventional. - Heavy tail structure, high interference drag, influence on rudder, Large vertical tail. V-Tail: + Low interference drag, Light structure, smaller tail area necessary, smaller hangar needed. - Control surface mixing is complex, Pitch and yaw control are performed by 1 surface pair. Canard-empennage: +High maneuverability, Improved overall lift and trim drag. - Large vertical tail, high induced drag, High wing-loading.

Answer 94

The reduction of effectiveness of lift due to close ground, which interferes with the smooth flow of air around wing.

Answer 95

1.-Using the graph (Taper Ratio, AR * tan(Λ_0%), tan(Λ_0%)/ β) obtain n_AC. For this use tan(Λ_0%)/ β value between 0 and 1. 2.-Use formula for x_AC

Answer 96

x_AC=(x_0,W+(n_AC,w * c_root,W))/c_MAC

Answer 97

1.- L= n_z * W_man 2.- L= qS_refC_L,max 3.-Multiply by M_To/M_To 4.-Organize for M_To/S

Answer 98

1.-∆n_z= ∆L_gust/W_man 2.- ∆L_gust = qS∆C_L 3.- Expand for ∆C_L=C_L𝛼 ∆𝛼 4.-Expand and multiply by W_TO/W_TO 5.- Use ∆𝛼 = w_g/V 5.- Solve for W_TO/S_ref

Answer 99

1.-SEP = V (T_man - D)/W_man 2.- Use relation n_z = L/W and expand to obtain C_L 3.- Expand D and substitute C_L obtained in step 2 with n_z = 1. 4.- Multiply Both sides of Eq by W_man 5.- Solve for T_man 6.- Divide both sides by W_TO 7.- Multiply Term containing the k by W_TO/W_TO 8.- Multiply both sides times T₀ and solve for 0/W_TO

Answer 100

1.- Expand the s_dec = V_TD² / 2a with V_TD = 1.15 V_s 2.- Multiply both sides times W_TO 3.- Solve for W_TO / S

Answer 101

-For STR Maneuvering Limit SEP=0 n_z <>1 -For Climb Gradient SEP <> 0, n_z = 1 -For Service Ceiling SEP = 0, n_z = 1

Test Prep Flashcards

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