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Aircraft Structures and Design 1Aero > Structures and Design Part 2 1Aero > Flashcards

Structures and Design Part 2 1Aero Flashcards

1
Q

if Wash out is Large then Induced Drag is

A

High

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2
Q

if Wash out is Small then Induced Drag is

A

Small

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3
Q

If Wash out is Large then Tip Stall is

A

Good

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4
Q

If Wash out is Small then Tip Stall is

A

Poor

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5
Q

If Wash out is Large then Wing Weight is

A

Midly Lower

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6
Q

If Wash out is Small then Wing Weight is

A

Midly Higher

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7
Q

(sometimes referred to as the mounting angle) is the angle between the chord line of the wing where the wing is mounted to the fuselage, and a reference axis along the fuselage

A

Angle of Incidence

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8
Q

Used to minimize drag at some operating condition, usually cruise.

A

Angle of Incidence

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9
Q

▪ set the wing at an angle to the longitudinal axis of the fuselage corresponding to the angle at which minimum drag occurs.
▪ Used to improve attitude
▪ Usually at 1-3 degrees

A

Angle of Incidence

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10
Q

Large Angle of Incidence means Cruise Drag is

A

High

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11
Q

Small Angle of Incidence means Cruise Drag is

A

Low

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12
Q

Large Angle of Incidence means Cockpit Visibility is

A

Good

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13
Q

Small Angle of Incidence means Cockpit Visibility is

A

Watch out

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14
Q

Large Angle of Incidence means Landing attitude in terms of nose gear hitting runway first is

A

Watch out

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15
Q

Small Angle of Incidence means Landing attitude in terms of nose gear hitting runway first is

A

No problem

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16
Q

Wing Position where:
▪ Places fuselage closer to the ground; easier loading/unloading; adapted by cargo aircraft
▪ Sufficient ground clearance for engine nacelle or propeller; less landing gear height needed

A

High Wing

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17
Q

Wing Position where:
▪ Wing tips less likely to strike the ground
▪ Usually less in weight (Semi-Cantiliver)
▪ A strutted wing usually presents less weight but struts adds to drag.
▪ Struts for a high wing, that is struts below the wing, offer less drag compared to struts above the wing

A

High Wing

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18
Q

Wing Position where:
▪ A strutted wing usually presents less weight but struts adds to drag.
▪ Struts that is struts below the wing, offer less drag compared to struts above the wing

A

High Wing

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19
Q

Wing Position where:
Weight savings for placing wing box at the top; no fuselage stiffening necessary; however, increased frontal area adds to drag
▪ For a STOL aircraft, provides ground clearance for the large flap necessary for high CL

A

High Wing

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20
Q

Wing Position where:
Prevents floating (ground effect is reduced) which makes it hard to land on desired spot
▪ STOL aircraft are usually designed to operate in unimproved fields; This wing places engines and propellers away from rocks and debris

A

High Wing

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21
Q

Wing Position where:
▪ Landing gear is installed to the fuselage rather than the wing to reduce strut length
▪ Fuselage needs stiffening; means more weight

A

High Wing

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22
Q

Wing Position where:
▪ External blisters (landing gear housing) might be necessary; means added weight and drag
▪ Fairing where wing connects to the circular fuselage is necessary
▪ Flattened bottom will provide desired floor height but means more weight

A

High Wing

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23
Q

Wing Position where:
▪ Needs fuselage stiffening; means more weight
▪ Carry-through structure will limit space for a passenger or cargo aircraft; difficult to incorporate in a fighter aircraft in which most of the fuselage is occupied by the jet engines and inlet ducts

A

Mid Wing

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24
Q

Wing Position where:
▪ Given enough ground clearance, aft-fuselage
▪ upsweep can be reduced, reducing drag

A

Low Wing

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24
Q

Wing Position where:
▪ Landing gear can be attached to (and retracted into) the wing which is already strong with no stiffening (and no external blisters) necessary
▪ Allows for a shorter landing gear strut which means less weight; however there still must be enough ground clearance

A

Low Wing

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25
Q

▪ Commonly adapted by large commercial transports which normally operate in well-equipped airfields; loading and unloading is not a problem

A

Low Wing

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25
Q

Wing Position where:
▪ Ground clearance problems may be alleviated by a dihedral; but too much dihedral can cause Dutch roll tendencies.

A

Low Wing

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26
Q

Wing Position where:
▪ Placing the propellers higher above the wing increases interference effects and cruise fuel consumption.

A

Low Wing

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27
Q

If the Wing Position is High then the Interferance Drag is

A

Poor

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28
Q

If the Wing Position is Mid then the Interferance Drag is

A

Good

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29
Q

If the Wing Position is Low then the Interferance Drag is

A

Poor

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30
Q

If the Wing Position is High then the Dihedral effect is

A

Negative

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31
Q

If the Wing Position is Mid then the Dihedral effect is

A

Neutral

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32
Q

If the Wing Position is Low then the Dihedral effect is

A

Positive

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33
Q

If the Wing Position is High and Mid then the Landing Gear: Wing Mounted , Fuselage Mounted is

A

Long/Heavy possibly draggy

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34
Q

If the Wing Position is Low then the Landing Gear: Wing Mounted , Fuselage Mounted is

A

Short/Light

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35
Q

the ratio between the shorter to the longer wing

A

Span Ratio

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35
Q

the vertical distance between the two wings

A

Gap

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36
Q

the longitudinal offset of the two wings relative to each other (positive, when upper wing is closer to the nose; negative, otherwise)

A

Stagger

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37
Q

relative incidence between the two wings (positive, when upper wing has a larger incidence; negative, otherwise)

A

Decalage

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38
Q

Biplane that has smaller lower wing than the upper wing

A

Sesquiplane

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39
Q

is though of as a member having a relatively large material in the flanges, chords, or caps located at the top and bottom member, with a relatively thin shear web connecting the two.

A

Wing Spar

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40
Q

is designed to be subjected to shear, bending and torsion.

A

Wing Spar

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41
Q
  • Form the wing box for stable torsion resistance
  • It may be classified as tension-field beam or shear resistant beam
A

Wing Spar

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42
Q

Spar Location : 12 to 17 % chord

A

Front Spar

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43
Q

Spar Location : 65% to 75%. Usually 70% to accommodate 25% chord aileron

A

Rear Spar

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44
Q

These consist of the upper and lower flanges attached to the
spar webs.

A

Spar Cap (flange)

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45
Q

carry the bending moment
generated by the wing in flight.

A

spar caps

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46
Q

The upper (Blank) will be
loaded in compression and the lower in tension for a positive
load factor (wing bending upward).

A

spar caps

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47
Q

also form a boundary onto which wing skin is attached and support the wing skin against buckling.

A

Spar Cap (flange)

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48
Q

Concentrated load points such as
engine mounts or landing gear are attached to the

A

main spar

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49
Q

consists of the material between the spar caps and maintains a fixed spacing between the them.

A

Spar web

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50
Q

This allows the spar caps to act in pure tension and compression (bending) during flight.

A

Spar web

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51
Q

is responsible for carrying the vertical shear loads (lift) which arises from the
aerodynamic loading of the wing.

A

Spar web

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52
Q

are collectively referred to as the wing spar

A

The spar webs and caps

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53
Q
  • allows the shear web to wrinkle, and this the transverse shear is resisted by tension in more or less the same way as wire
    -braced truss.
A

Tension-field beam

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54
Q
  • will not wrinkle would not occur until load limit was imposed, so that a loads less than the load limit, the spar can be considered a shear resistant beam
A

Tension-field beam

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55
Q
  • designed so that the shear web will not wrinkle under limit loads
  • In order to increase the shear load that the web can withstand, stiffeners are attached at specified intervals
A

Shear resistant Beam

56
Q

The primary purpose of (Blank) in wings is to add bending strength to the wings

A

Stringers

57
Q

spacing is determined by the number required for the loads imposed.
Longitudinal members are spaced from 6 to 12 inches apart around the largest cross section.

A

Stringers

58
Q

Since the cross section gradually decreases in size, the spacing is closer towards the tail post so that alternated members may be stopped at a forward frame.
It is desirable not to end all the longitudinal members at the same frame.

A

Stringers

59
Q

The primary function of the (blank) in the wing are
1. to maintain the chordwise shape of the airfoil
2. Act as supports of the wing skin panel or envelope
3. Transmit the pressures on the wing to the spanwise members

A

Ribs

60
Q

they also serve to act as the support members to which the landing gear members or engine mount members are attached or as support for fuel tanks, control systems and localized loads

A

Ribs

61
Q

The spacing of (blank) may be determined by the need to prevent oil canning of the skin or by the optimum panel proportions.
For preliminary considerations, (blank) spacing from 6 to 18 inches may be assumed

A

Ribs

62
Q

Wing Attachments:
- reduction of the bending moment imposed produces Lighter structure

A

Externally braced - Semi-Cantilever

63
Q

Wing Attachments:
- Any gain in wing structure may be offset by the additional supporting structure
- Causes more drag

A

Externally braced - Semi-Cantilever

64
Q

Wing Attachments:
- No external brace
- May be heavier due wing junction will carry the bending moment
- Less drag

A

Externally braced - Semi-Cantilever

65
Q

This devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag.

A

Wing Devices

66
Q

their intended effect is always to reduce an aircraft’s drag by partial recovery of the tip vortex energy. Such devices increase the effective aspect ratio of a wing without greatly increasing the wingspan

A

Wing Devices

67
Q

Types of Wing Tips:
is more effective than a rounded tip in alleviating tip vortex effects

A

sharp tip

68
Q

Types of Wing Tips:
is the most widely used low-drag wingtip

A

Hoerner tip

69
Q

Types of Wing Tips:
increase effective span without increasing actual span

A

Tip curved upwards/downwards

70
Q

Types of Wing Tips:
addresses the condition that vortices tend to be located at the trailing edge of the wing tip; increases torsional load

A

swept wing tip

71
Q

Types of Wing Tips:
is used for supersonic aircraft; part with little lift is cut-off; reduced torsional load

A

Cut-off forward swept

72
Q

Types of Wing Tips:
is an intuitive solution to the leakage of the high pressure flow below the wing to the low pressure flow above it.

A

endplate

73
Q

Positive factors of Wing Tip Devices:
* Induced drag is reduced at

A

takeoff and cruise

74
Q

Positive factors of Wing Tip Devices:
is sometimes reduced a little at cruise due to the change in span load produced by the device.

A

Shock Drag

75
Q

Offsetting factors of Wing Tip Devices:
* Profile drag is increased due to:
– Increased

A

Wetted Area

76
Q

Offsetting factors of Wing Tip Devices:
* Weight is increased due to:

A

Weight of the device itself

77
Q
  • areas inside the aircraft structure that have been sealed to allow fuel storage
  • Inspection panels must be provided to allow internal inspection, repair, and overall servicing
A

Integral fuel tank

78
Q
  • The Vertical Tail surface consist of the fixed surface and the movable surface (rudder)
A

Vertical Stabilizers

79
Q

Its function is to provide directional stability and control in flight

A

Vertical Stabilizers

80
Q
  • It is very important that these tail surfaces be located that they are not blanketed by the fuselage
A

Vertical Stabilizers

81
Q
  • The aspect ratio of the (Blank) surface may somewhat restricted by the possible torsional moment imposed on the fuselage
A

Vertical Tail

82
Q
  • Typical aspect ratio is around range 2 to 4
A

Vertical Stabilizers

83
Q
  • Dependent on the distance from C.G.
  • Range from 10 to 15 percent of wing area
A

Vertical Stabilizers Area

84
Q

is around 30 to 50 percent of stabilizer area

A

Rudder

85
Q
  • Located at the distance from C.G to the estimated CP of the horizontal or vertical stabilizer is form 2.5 to 3.5 times the wing mean geometric chord
A

Tail Length

86
Q

May be added to increase the fin area
(1) increase directional stability of the original surface

A

Dorsal Fin

87
Q

(2) transmit the loads on the fin to greater number of the fuselage frames
(3) reduce torsional moment about the longitudinal axis

A

Dorsal Fin

88
Q

(4) reduce height of the vertical tail
(5) possible weight saving

A

Dorsal Fin

89
Q

Located below the fuselage
More effective since area is not blanketed by the fuselage

A

Ventral Fin

90
Q

▪ Lighter construction
▪ Fuselage blankets the vertical Stabilizer

A

Single Vertical Tail

91
Q

▪ Undistrubed flow in vertical tails at high angles of attack
▪ May enhance engine out control in multiengine aircraft with the rudders positioned in the propwash

A

Multiple Vertical Tail

92
Q

▪ Endplate effect on the horizontal tail; reduced size possible
▪ Heavier than conventional

A

Multiple Vertical Tail

93
Q
  • Horizontal Tail consist of the (blank) and the elevator
  • This should be located that any blanketing by the wing or the fuselage is avoided.
A

Horizontal Stabilizers

94
Q
  • Partial blanketing usually exist, however certain features may be incorporate to limit the effect.
  • Conventional airplane locate the tail surface about 2.5 to 4 MAC length behind the CG to assure reasonable static longitudinal stability
A

Horizontal Stabilizers

95
Q

▪ It works! Adapted by about 70% or more of aircraft in service (Raymer)
▪ Relatively lightweight

A

Conventional Tail

96
Q

▪ Horizontal tail is in the wake of the wing
▪ Does not allow for an aft-mounted engine
▪ Low horizontal tails are best for stall recovery

A

Conventional Tail

97
Q

▪ Heavier than conventional due to strengthening of the vertical tail to support the horizontal tail
▪ Allows for a smaller vertical tail due to end plate effect

A

T-Tail

98
Q

▪ Horizontal tail is clear of wing wake and propwash
▪ Allows for an aft-mounted engine
▪ Prone to deep stall due wing blanketing at High angle of attack

A

T-Tail

99
Q

Tail Configurations:
▪ Contributes to lift; higher aspect ratio for reduced induced drag; greater camber for increased lift

A

Canard

100
Q

▪ Theoretically more efficient than an aft-tailed aircraft; wing lift reduced - smaller wing; in aft-tailed aircraft, tail produces negative lift for stability – wing must produce more lift – bigger wing.

A

Canard

101
Q

▪ Pushes wing aft; bigger pitching moments due to flaps

A

Canard

102
Q

Tail Configurations:
is closer to CG; less effective pitch control; surface must be increased; resulting in more trim drag
▪ Pitch up tendencies are avoided

A

Canard

103
Q

Tail Configurations:
▪ May allow for a reduced wetted area
▪ Reduced interference drag

A

V-Tail

104
Q

Tail Configurations:
▪ Control/Actuation complexity
▪ Adverse roll-yaw coupling
▪ Surfaces are out of the wing wake

A

V-Tail

105
Q

Tail Configurations:
▪ Theoretically offers minimum trim drag
▪ Additional weight; more interference drag; complexity

A

Three (3) Plane

106
Q

Weight of the aileron, elevator, rudder & flaps controls is assumed to be a function of Wingspan

A

Design Consideration

107
Q

Primary Flight Controls:
* control roll about the longitudinal axis.
* attached to the outboard trailing edge of each wing

A

Ailerons

108
Q

Primary Flight Controls:
* move in the opposite direction from each other.
* Around 25 to 27% chord of the wing

A

Ailerons

109
Q

is the natural and undesirable tendency for an aircraft to yaw in the opposite direction of a roll.

A

Adverse Yaw

110
Q

The downward deflected aileron produces more lift as evidenced by the wing raising, it also produces more drag.

A

Adverse Yaw

111
Q

This added drag causes the wing to slow down slightly. This results in the aircraft yawing toward the wing which had experienced an increase in lift (and drag).

A

Adverse Yaw

112
Q

one aileron is raised a greater distance than the other aileron is lowered for a given movement

A

Differential Ailerons

113
Q

when pressure is applied to the control wheel or control stick, the aileron that is being raised pivots on an offset hinge. This projects the leading edge of the aileron into the airflow and creates drag

A

Frise-Type Ailerons

114
Q

Corrects for aileron drag by automatically deflecting the rudder at the same time the ailerons are deflected

A

Coupled Ailerons and Rudder

115
Q

Combine both aspects of flaps and ailerons. A mixer is used to combine the separate pilot inputs into this single set of control surfaces

A

Flaperons

116
Q

An aileron flap combination could be employed whereby the aileron function would take place form any flap position

A

Flaperons

117
Q

Primary Controls:
* Both (blank) operate at low speed to give maximum control

A

Inboard and Outboard Aileron

118
Q

Primary Controls:
* Only (blank) operates at high speed to avoid over control

A

inboard Aileron

119
Q

controls pitch about the lateral axis.

A

Elevator

120
Q

Elevator controls:
* When the control column is pulled, the elevator goes

A

up and aircraft pitches up

121
Q

Elevator Control:
*When the control column is pushed, the elevator

A

down and aircraft pitches down

122
Q

Stability, power, thrust line, and the position of the horizontal tail surfaces on the empennage are factors in elevator effectiveness - ?

A

controlling pitch.

123
Q

Factors that affect Elevator effectivity
* Distance from

A

C.G

124
Q

Factors that affect Elevator effectivity:
* Aerodynamic effectiveness of

A

Surface

125
Q

Factors that affect Elevator effectivity:
- Thrust -?

A

Line

126
Q

Factors that affect Elevator effectivity:
* position of the horizontal tail surfaces on the

A

empennage

127
Q

controls movement of the aircraft about its vertical axis. This motion is called yaw

A

Rudder

128
Q
  • When the (blank) is deflected into the airflow, a horizontal force is exerted in the opposite direction.
A

Rudder

129
Q

(Blank) effectiveness increases with speed; therefore, large deflections at low speeds and small deflections at high speeds may be required to provide the desired reaction

A

Rudder

130
Q

Secondary Flight Controls:
- Attached to the trailing edge of the wing, increase both lift and induced drag for any given AOA

A

Flaps

131
Q

Secondary Flight Controls:
- It increases the airfoil camber, resulting in a significant increase in the coefficient of lift (CL) at a given AOA.
It greatly increases drag and moves the center of pressure (CP) aft on the airfoil

A

Plain Flaps

132
Q

Secondary Flight Controls:
- is deflected from the lower surface of the airfoil and produces a slightly greater increase in lift than the plain flap. More drag is created because of the turbulent air pattern produced behind the airfoil

A

Split Flaps

133
Q

Secondary Flight Controls:
The high energy air from the slot accelerates the upper surface boundary layer and delays airflow separation, providing a higher CL. Higher CL than lain and split Flap

A

Slotted Flaps

134
Q

Secondary Flight Controls:
Instead of rotating down on a hinge, it slides backwards on tracks.

A

Fowler Flaps

135
Q

Secondary Flight Controls:
In the first portion of its extension, it increases the drag very little, but increases the lift a great deal as it increases both the area and camber.

A

Fowler Flaps

136
Q

Leading Edge Devices:
- Direct airflow to the upper wing surface and delay airflow separation at higher angles of attack.

A

Fixed Slot

137
Q

Leading Edge Devices:
- The slot does not increase the wing camber, but allows a higher maximum CL because the stall is delayed

A

Fixed Slot

138
Q

Leading Edge Devices:
- At low angles of attack, each slat is held flush against the wing’s leading edge by the high pressure that forms at the wing’s leading edge

A

Moveable Slot

139
Q

Leading Edge Devices:
Opening a slat allows the air below the wing to flow over the wing’s upper surface, delaying airflow separation

A

Moveable Slot

140
Q

Leading Edge Devices:
used to increase both CL-MAX and the camber of the wings. frequently used in conjunction with trailing edge flaps and can reduce the nose-down pitching

A

Leading Edge Flap

141
Q

Leading Edge Devices:
Increase both CL-MAX and the camber of the wings. The fixed nature of leading edge cuffs extracts a penalty in maximum cruise airspeed

A

Leading Edge Cuff

Aircraft Structures and Design 1Aero (10 decks)

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