Structures and Design Part 2 1Aero Flashcards
1
Q
if Wash out is Large then Induced Drag is
A
High
2
Q
if Wash out is Small then Induced Drag is
A
Small
3
Q
If Wash out is Large then Tip Stall is
A
Good
4
Q
If Wash out is Small then Tip Stall is
A
Poor
5
Q
If Wash out is Large then Wing Weight is
A
Midly Lower
6
Q
If Wash out is Small then Wing Weight is
A
Midly Higher
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
8
Q
Used to minimize drag at some operating condition, usually cruise.
A
Angle of Incidence
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
10
Q
Large Angle of Incidence means Cruise Drag is
A
High
11
Q
Small Angle of Incidence means Cruise Drag is
A
Low
12
Q
Large Angle of Incidence means Cockpit Visibility is
A
Good
13
Q
Small Angle of Incidence means Cockpit Visibility is
A
Watch out
14
Q
Large Angle of Incidence means Landing attitude in terms of nose gear hitting runway first is
A
Watch out
15
Q
Small Angle of Incidence means Landing attitude in terms of nose gear hitting runway first is
A
No problem
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
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
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
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
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
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
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
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
24
Q
Wing Position where:
▪ Given enough ground clearance, aft-fuselage
▪ upsweep can be reduced, reducing drag
A
Low Wing
24
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
Low Wing
25
▪ Commonly adapted by large commercial transports which normally operate in well-equipped airfields; loading and unloading is not a problem
Low Wing
25
Wing Position where:
▪ Ground clearance problems may be alleviated by a dihedral; but too much dihedral can cause Dutch roll tendencies.
Low Wing
26
Wing Position where:
▪ Placing the propellers higher above the wing increases interference effects and cruise fuel consumption.
Low Wing
27
If the Wing Position is High then the Interferance Drag is
Poor
28
If the Wing Position is Mid then the Interferance Drag is
Good
29
If the Wing Position is Low then the Interferance Drag is
Poor
30
If the Wing Position is High then the Dihedral effect is
Negative
31
If the Wing Position is Mid then the Dihedral effect is
Neutral
32
If the Wing Position is Low then the Dihedral effect is
Positive
33
If the Wing Position is High and Mid then the Landing Gear: Wing Mounted , Fuselage Mounted is
Long/Heavy possibly draggy
34
If the Wing Position is Low then the Landing Gear: Wing Mounted , Fuselage Mounted is
Short/Light
35
the ratio between the shorter to the longer wing
Span Ratio
35
the vertical distance between the two wings
Gap
36
the longitudinal offset of the two wings relative to each other (positive, when upper wing is closer to the nose; negative, otherwise)
Stagger
37
relative incidence between the two wings (positive, when upper wing has a larger incidence; negative, otherwise)
Decalage
38
Biplane that has smaller lower wing than the upper wing
Sesquiplane
39
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.
Wing Spar
40
is designed to be subjected to shear, bending and torsion.
Wing Spar
41
* Form the wing box for stable torsion resistance
* It may be classified as tension-field beam or shear resistant beam
Wing Spar
42
Spar Location : 12 to 17 % chord
Front Spar
43
Spar Location : 65% to 75%. Usually 70% to accommodate 25% chord aileron
Rear Spar
44
These consist of the upper and lower flanges attached to the
spar webs.
Spar Cap (flange)
45
carry the bending moment
generated by the wing in flight.
spar caps
46
The upper (Blank) will be
loaded in compression and the lower in tension for a positive
load factor (wing bending upward).
spar caps
47
also form a boundary onto which wing skin is attached and support the wing skin against buckling.
Spar Cap (flange)
48
Concentrated load points such as
engine mounts or landing gear are attached to the
main spar
49
consists of the material between the spar caps and maintains a fixed spacing between the them.
Spar web
50
This allows the spar caps to act in pure tension and compression (bending) during flight.
Spar web
51
is responsible for carrying the vertical shear loads (lift) which arises from the
aerodynamic loading of the wing.
Spar web
52
are collectively referred to as the wing spar
The spar webs and caps
53
- 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.
Tension-field beam
54
- 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
Tension-field beam
55
- 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
Shear resistant Beam
56
The primary purpose of (Blank) in wings is to add bending strength to the wings
Stringers
57
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.
Stringers
58
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.
Stringers
59
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
Ribs
60
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
Ribs
61
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
Ribs
62
Wing Attachments:
- reduction of the bending moment imposed produces Lighter structure
Externally braced - Semi-Cantilever
63
Wing Attachments:
- Any gain in wing structure may be offset by the additional supporting structure
- Causes more drag
Externally braced - Semi-Cantilever
64
Wing Attachments:
- No external brace
- May be heavier due wing junction will carry the bending moment
- Less drag
Externally braced - Semi-Cantilever
65
This devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag.
Wing Devices
66
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
Wing Devices
67
Types of Wing Tips:
is more effective than a rounded tip in alleviating tip vortex effects
sharp tip
68
Types of Wing Tips:
is the most widely used low-drag wingtip
Hoerner tip
69
Types of Wing Tips:
increase effective span without increasing actual span
Tip curved upwards/downwards
70
Types of Wing Tips:
addresses the condition that vortices tend to be located at the trailing edge of the wing tip; increases torsional load
swept wing tip
71
Types of Wing Tips:
is used for supersonic aircraft; part with little lift is cut-off; reduced torsional load
Cut-off forward swept
72
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.
endplate
73
Positive factors of Wing Tip Devices:
* Induced drag is reduced at
takeoff and cruise
74
Positive factors of Wing Tip Devices:
is sometimes reduced a little at cruise due to the change in span load produced by the device.
Shock Drag
75
Offsetting factors of Wing Tip Devices:
* Profile drag is increased due to:
– Increased
Wetted Area
76
Offsetting factors of Wing Tip Devices:
* Weight is increased due to:
Weight of the device itself
77
* 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
Integral fuel tank
78
* The Vertical Tail surface consist of the fixed surface and the movable surface (rudder)
Vertical Stabilizers
79
Its function is to provide directional stability and control in flight
Vertical Stabilizers
80
* It is very important that these tail surfaces be located that they are not blanketed by the fuselage
Vertical Stabilizers
81
* The aspect ratio of the (Blank) surface may somewhat restricted by the possible torsional moment imposed on the fuselage
Vertical Tail
82
* Typical aspect ratio is around range 2 to 4
Vertical Stabilizers
83
* Dependent on the distance from C.G.
* Range from 10 to 15 percent of wing area
Vertical Stabilizers Area
84
is around 30 to 50 percent of stabilizer area
Rudder
85
* 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
Tail Length
86
May be added to increase the fin area
(1) increase directional stability of the original surface
Dorsal Fin
87
(2) transmit the loads on the fin to greater number of the fuselage frames
(3) reduce torsional moment about the longitudinal axis
Dorsal Fin
88
(4) reduce height of the vertical tail
(5) possible weight saving
Dorsal Fin
89
Located below the fuselage
More effective since area is not blanketed by the fuselage
Ventral Fin
90
▪ Lighter construction
▪ Fuselage blankets the vertical Stabilizer
Single Vertical Tail
91
▪ 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
Multiple Vertical Tail
92
▪ Endplate effect on the horizontal tail; reduced size possible
▪ Heavier than conventional
Multiple Vertical Tail
93
* Horizontal Tail consist of the (blank) and the elevator
* This should be located that any blanketing by the wing or the fuselage is avoided.
Horizontal Stabilizers
94
* 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
Horizontal Stabilizers
95
▪ It works! Adapted by about 70% or more of aircraft in service (Raymer)
▪ Relatively lightweight
Conventional Tail
96
▪ 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
Conventional Tail
97
▪ 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
T-Tail
98
▪ 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
T-Tail
99
Tail Configurations:
▪ Contributes to lift; higher aspect ratio for reduced induced drag; greater camber for increased lift
Canard
100
▪ 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.
Canard
101
▪ Pushes wing aft; bigger pitching moments due to flaps
Canard
102
Tail Configurations:
is closer to CG; less effective pitch control; surface must be increased; resulting in more trim drag
▪ Pitch up tendencies are avoided
Canard
103
Tail Configurations:
▪ May allow for a reduced wetted area
▪ Reduced interference drag
V-Tail
104
Tail Configurations:
▪ Control/Actuation complexity
▪ Adverse roll-yaw coupling
▪ Surfaces are out of the wing wake
V-Tail
105
Tail Configurations:
▪ Theoretically offers minimum trim drag
▪ Additional weight; more interference drag; complexity
Three (3) Plane
106
Weight of the aileron, elevator, rudder & flaps controls is assumed to be a function of Wingspan
Design Consideration
107
Primary Flight Controls:
* control roll about the longitudinal axis.
* attached to the outboard trailing edge of each wing
Ailerons
108
Primary Flight Controls:
* move in the opposite direction from each other.
* Around 25 to 27% chord of the wing
Ailerons
109
is the natural and undesirable tendency for an aircraft to yaw in the opposite direction of a roll.
Adverse Yaw
110
The downward deflected aileron produces more lift as evidenced by the wing raising, it also produces more drag.
Adverse Yaw
111
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).
Adverse Yaw
112
one aileron is raised a greater distance than the other aileron is lowered for a given movement
Differential Ailerons
113
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
Frise-Type Ailerons
114
Corrects for aileron drag by automatically deflecting the rudder at the same time the ailerons are deflected
Coupled Ailerons and Rudder
115
Combine both aspects of flaps and ailerons. A mixer is used to combine the separate pilot inputs into this single set of control surfaces
Flaperons
116
An aileron flap combination could be employed whereby the aileron function would take place form any flap position
Flaperons
117
Primary Controls:
* Both (blank) operate at low speed to give maximum control
Inboard and Outboard Aileron
118
Primary Controls:
* Only (blank) operates at high speed to avoid over control
inboard Aileron
119
controls pitch about the lateral axis.
Elevator
120
Elevator controls:
* When the control column is pulled, the elevator goes
up and aircraft pitches up
121
Elevator Control:
*When the control column is pushed, the elevator
down and aircraft pitches down
122
Stability, power, thrust line, and the position of the horizontal tail surfaces on the empennage are factors in elevator effectiveness - ?
controlling pitch.
123
Factors that affect Elevator effectivity
* Distance from
C.G
124
Factors that affect Elevator effectivity:
* Aerodynamic effectiveness of
Surface
125
Factors that affect Elevator effectivity:
- Thrust -?
Line
126
Factors that affect Elevator effectivity:
* position of the horizontal tail surfaces on the
empennage
127
controls movement of the aircraft about its vertical axis. This motion is called yaw
Rudder
128
* When the (blank) is deflected into the airflow, a horizontal force is exerted in the opposite direction.
Rudder
129
(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
Rudder
130
Secondary Flight Controls:
- Attached to the trailing edge of the wing, increase both lift and induced drag for any given AOA
Flaps
131
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
Plain Flaps
132
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
Split Flaps
133
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
Slotted Flaps
134
Secondary Flight Controls:
Instead of rotating down on a hinge, it slides backwards on tracks.
Fowler Flaps
135
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.
Fowler Flaps
136
Leading Edge Devices:
- Direct airflow to the upper wing surface and delay airflow separation at higher angles of attack.
Fixed Slot
137
Leading Edge Devices:
- The slot does not increase the wing camber, but allows a higher maximum CL because the stall is delayed
Fixed Slot
138
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
Moveable Slot
139
Leading Edge Devices:
Opening a slat allows the air below the wing to flow over the wing’s upper surface, delaying airflow separation
Moveable Slot
140
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
Leading Edge Flap
141
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
Leading Edge Cuff
