STRUCTURES MMTB Flashcards
The basic questions of
configuration, arrangement,
size and weight, and
performance are answered
Conceptual Design
Begins when the major changes are over
Preliminary Design
Begins in which the actual
pieces to be fabricated are designed.
Detail Design
Mathematical modeling of the outside
skin of the aircraft with sufficient
accuracy to ensure proper fit between its
different parts designed by different designers.
Lofting
Structural Weight is between 30 to 35%
of the total weight
PRELIMINARY WEIGHT ESTIMATE
Total Weight of the aircraft as it begins the mission for which it was designed.
Design Take-off Gross Weight
𝑊𝐶𝑟𝑒𝑤 + 𝑊𝑝𝑎𝑦𝑙𝑜𝑎𝑑 + 𝑊𝑓𝑢𝑒𝑙 + 𝑊𝑒𝑚𝑝𝑡
𝑊0/ total weight
Part of the fuel supply that is available for
performing the mission
Mission Fuel
Fuel which cannot be pumped out of the
tanks
Trapped Fuel
The firing of gun and missiles, and is often
left out of the sizing analysis
Weapon Drop
Rate of fuel consumption divided by the
thrust
Specific Fuel Consumption
A measure of the design’s overall aerodynamic efficiency
Lift-to-Drag Ratio
Curvature characteristics of most airfoil
Camber
Line equidistant from the upper and lower surfaces
Mean Camber Line
Maximum thickness of the airfoil divided by its chord
Airfoil Thickness Ratio
𝑡/c
Thickness Ratio
Point about which the pitching moment
remains constant for any angle of attack
Aerodynamic Center
Ratio between the dynamic and the
viscous forces in a liquid
Reynold’s Number
Lift coefficient at which the airfoil has the
best 𝐿⁄𝐷
Point in the airfoil drag polar that is tangent to a line from origin and closest
to the vertical axis
DESIGN LIFT COEFFICIENT
Stall from the trailing edge
Turbulent boundary layer increases with
angle of attack
Fat Airfoils (𝒕⁄𝒄 > 𝟏𝟒%)
Flow Separates near the nose at a very small angle of attack but reattaches itself so that little effect is felt.
At higher angle of attacks the flow fails to
attach, which almost immediately stalls
the entire airfoil
Moderate Thick Airfoils (6-14%)
The flow separates from the nose at a
small angle and reattaches almost
immediately
Very Thin Airfoils (𝒕⁄𝒄 < 𝟔%)
Cause the wing to stall first at the root.
Twisting/Washout
Drag increases with increasing thickness
due to separation
AIRFOIL THICKNESS RATIO
For a wing of fairly high aspect ratio and
moderate sweep, a larger nose radius
provides higher stall angle and greater
maximum lift coefficient
AIRFOIL THICKNESS RATIO
Wing structural weight varies approximately inversely with the square
root of the thickness ratio
AIRFOIL THICKNESS RATIO
Angle of concern in supersonic flight
It is common to sweep the leading edge behind the Mach cone to reduce drag.
Leading Edge Sweep
Sweep most related to subsonic flight.
Quarter-Chord Line Sweep
Aerodynamic Center for SUBSONIC
0.25c
Aerodynamic Center for SUPERSONIC
0.4c
Has tips farther apart making them less affected by the tip vortex and the tip vortex strength is reduced
High aspect ratio wings
Wing weight increasing with___
increasing aspect ratio
will stall at a
higher angle of attack than higher aspect ratio wings
Lower aspect ratio wings
If the Aspect ratio is High, the Induced Drag is _______
Low
If the Aspect ratio is High, the Lift-Curve Slope is _______
High
If the Aspect ratio is High, the Pitch Attitude is _______
Low
If the Aspect ratio is High, the Ride in Turbulence is _______
Poor
If the Aspect ratio is High, the Wing Weight is _______
High
If the Aspect ratio is High, the Wing Span is _______
Large
If the Aspect ratio is Low, the Induced Drag is _______
High
If the Aspect ratio is Low, the Lift-Curve Slope is _______
Low
If the Aspect ratio is High, the Pitch Attitude is _______
High
If the Aspect ratio is Low, the Ride in Turbulence is _______
Good
If the Aspect ratio is Low, the Wing Weight is _______
Low
If the Aspect ratio is Low, the Wing Span is _______
Small
Primarily used to reduce the adverse
effects of transonic and supersonic flow
WING SWEEP
are wings with one wing
swept aft and the other swept forward.
Oblique wings
tend to have lower wave
drag
Oblique wings
improves stability
Wing sweep
increases the effectiveness of vertical tails at the wing tips
Wing sweep
Better ride through turbulence characteristics
Wing sweep
Increases Critical Mach Number
Wing sweep
Highly undesirable tendency, upon
reaching an AOA near stall, to suddenly
and uncontrollably increase AOA
Pitch up
Solution to constant sweep problems
Variable Sweep
Complex and attendant balance problems
Variable Sweep
If there is an increased wing sweep forward, the Lift-Curve Slope is ___
Low
If there is an increased wing sweep forward, the Pitch Attitude in Low
Speed, Level Flight is ___
High
If there is an increased wing sweep forward, the Ride through Turbulence is ___
Good
If there is an increased wing sweep forward, the Asymmetric Stall is ___
Best
If there is an increased wing sweep forward, the Lateral Control at Stall is ___
Best
If there is an increased wing sweep forward, the Compressibility Drag is ___
Low
If there is an increased wing sweep forward, the Wing Weight is ___
Highest
If there is an increased wing sweep on none, the Lift-Curve Slope is ___
High
If there is an increased wing sweep (none), the Pitch Attitude in Low
Speed, Level Flight is ___
Low
If there is an increased wing sweep (none), the Ride through Turbulence is ___
Poor
If there is an increased wing sweep (none), the Asymmetric Stall is ___
Good
If there is an increased wing sweep (none), the Lateral Control at Stall is ___
Good
If there is an increased wing sweep (none), the Compressibility Drag is ___
High
If there is an increased wing sweep (none), the Wing Weight is ___
Low
If there is an increased wing sweep aft, the Lift-Curve Slope is ___
Low
If there is an increased wing sweep aft, the Pitch Attitude in Low
Speed, Level Flight is ___
High
If there is an increased wing sweep aft, the Ride through Turbulence is ___
Good
If there is an increased wing sweep aft, the Asymmetric Stall is ___
Poor
If there is an increased wing sweep aft, the Lateral Control at Stall is ___
Poor
If there is an increased wing sweep aft, the Compressibility Drag is ___
Low
If there is an increased wing sweep aft, the Wing Weight is ___
High
Ratio between the tip chord and the centerline tip chord
Taper Ratio
Affects the distribution of lift along the span of the wing
Taper Ratio
More taper
lesser the weight
Less taper means
more fuel volume
If there is High Taper Ratio, the Wing Weight is ____
High
If there is High Taper Ratio, the Tip stall is ____
Good
If there is High Taper Ratio, the Wing Fuel Volume is ____
Poor
Used to prevent tip stall and to revise the
lift distribution to approximate an ellipse
TWIST
Actual change in airfoil angle of incidence, usually measured with respect
to the root airfoil
Geometric Twist
Twist angle changes in proportion to the distance from the root airfoil
Linear Twist
Angle between zero-lift angle of an airfoil
and the zero-lift angle of the root airfoil
Aerodynamic Twist
If identical airfoil is used root to tip, aerodynamic twist is_____ as the
geometric twist
the same
If there is a Large Twist Angle the Induced Drag is,
High
If there is a Small Twist Angle the Induced Drag is
Small
If there is a Large Twist Angle the Tip Stall is,
Good
If there is a Small Twist Angle the Tip Stall is
Poor
If there is a Large Twist Angle the Wing Weight is,
Mildly Lower
If there is a Small Twist Angle the Wing Weight is,
Mildly Higher
The pitch angle of the wing with respect
to the fuselage
WING INCIDENCE
Minimizes drag at some operating conditions, usually cruise
WING INCIDENCE
If the WING INCIDENCE IS LARGE, the Cruise Drag is ___
High
If the WING INCIDENCE IS SMALL, the Cruise Drag is ___
Small
If the WING INCIDENCE IS LARGE, the Cockpit
Visibility is ___
Good
If the WING INCIDENCE IS SMALL, the Cockpit
Visibility is ___
Watch out
If the WING INCIDENCE IS LARGE, the Landing
Attitude is ___
Watch out
If the WING INCIDENCE IS SMALL, the Landing
Attitude is ___
No problem
Angle of the wing with respect to the horizontal when seen from the front
DIHEDRAL
Tends to roll an aircraft whenever it is banked
DIHEDRAL
_____of sweep provides about 1° of effective dihedral
10°
Produced by excessive dihedral effect
Dutch Roll
Repeated side-to-side motion involving yaw and roll
Dutch Roll
To counter the tendency of Dutch Roll, the vertical
area must be _____
increased
If there is a POSITIVE DIHEDRAL, the Spiral Stability is ____
Increased
If there is a POSITIVE DIHEDRAL, the Dutch Roll Stability is ____
Decreased
If there is a POSITIVE DIHEDRAL, the Ground Clearance is ____
Increased
If there is a NEGATIVE DIHEDRAL, the Spiral Stability is ____
Decreased
If there is a NEGATIVE DIHEDRAL, the Dutch Roll Stability is ____
Increased
If there is a NEGATIVE DIHEDRAL, the Ground Clearance is ____
Decreased
Allows placing of the fuselage closer to
the ground
High Wing
Provides sufficient ground clearance without excessive landing gear length
High Wing
Wingtips less likely to strike the ground
High Wing
usually presents less
weight but struts adds to drag
strutted wing
For a ______ aircraft, a high wing provides ground clearance for the large flap necessary for high CL
STOL
Prevents floating which makes it hard to
land on desired spot
High Wing
Intended to operate at unimproved fields
High Wing
External blisters and stiffening is needed
which adds weight and drag
High Wing
Better visibility towards the ground
High Wing
Restricted visibility towards the rear
High Wing
Obscures pilot vision in a turn
High Wing
Blocks upward visibility in a climb
High Wing
Least interference drag
Mid Wing
to a degree, has the ground clearance
advantage of the high wing
Mid Wing
Superior aerobatic maneuverability due
to absence of actual or effective dihedral
which will act in the wrong direction in
inverted flight
Mid Wing
Needs fuselage stiffening; means more weight
Mid Wing
Carry-through structure will limit space for a passenger or cargo aircraft
Mid Wing
Landing gear can be attached to the wing
Mid Wing
Allows for a shorter landing gear strut which means less weight; however there still must be enough ground clearance
Mid Wing
Given enough ground clearance, aft fuselage upsweep can be reduced,
reducing drag
Mid Wing
Ground clearance problems may be alleviated by a dihedral
Mid Wing
Placing the propeller above the wing
increases interference effects and cruise fuel consumption
Low Wing
Affects take-off and landing field length,
cruise performance, ride through turbulence and weight
WING SIZE AND WING LOADING
Wings can be kept small using ___
flaps
For flight at high altitudes and at low speeds, a ______ is required
larger wing
In High Wing aircraft the Interference Drag is _____
Poor
In High Wing aircraft the Dihedral Effect is _____
Negative
In High Wing aircraft the Passenger Visibility is _____
Good
In High Wing aircraft the Fuselage Mounted is _____
Long/Heavy
In High Wing aircraft the Wing Mounted is _____
Possibly Draggy
In High Wing aircraft the Loading & Unloading is _____
Easy
In Mid Wing aircraft the Interference Drag is _____
Good
In Mid Wing aircraft the Dihedral Effect is _____
Neutral
In Mid Wing aircraft the Passenger Visibility
is _____
Good
In Mid Wing aircraft the Fuselage Mounted is _____
Long/Heavy
In Mid Wing aircraft the Wing Mounted is _____
Possibly Draggy
In Mid Wing aircraft the Loading & Unloading is _____
Easy
In Low Wing aircraft the Interference Drag is _____
Poor
In Low Wing aircraft the Dihedral Effect is _____
Positive
In Low Wing aircraft the Passenger Visibility
is _____
Poor for some
In Low Wing aircraft the Fuselage Mounted is _____
Long/Heavy
In Low Wing aircraft the Wing Mounted is _____
Short/Light
In Low Wing aircraft the Loading & Unloading is _____
Need Stairs
If the Wing Loading is High, the Field Length is ____
Long
If the Wing Loading is High, the Stall Speed is ____
High
If the Wing Loading is High, the Max. Lift-to-Drag Ratio is ____
High
If the Wing Loading is Low, the Stall Speed is ____
Low
If the Wing Loading is High, the Ride quality in
Turbulence is ____
Good
If the Wing Loading is High, the Weight is ____
Low
If the Wing Loading is Low, the Field Length is ____
Short
If the Wing Loading is Low, the Max. Lift-to-Drag Ratio is ____
Low
If the Wing Loading is Low, the Ride quality in
Turbulence is ____
Bad
If the Wing Loading is Low, the Weight is ____
High
A ____ tip is more effective than a rounded tip in alleviating tip vortex
effects
Sharp
The ____ tip is the most widely used low-drag wingtip
Hoerner
Tip curved upwards/downwards increase effective span without increasing actual span
WING TIPS
A ______ tip addresses the condition that vortices tend to be located at the
trailing edge of the wing tip; increases torsional load
swept wing
It is used for supersonic aircraft; part with little lift is cut-off; reduced torsional load
Cut-off forward swept
Low structural Weight
BIPLANE WINGS
Relatively short wing span
BIPLANE WINGS
Half induced drag compared to monoplane producing same lift
BIPLANE WINGS
The vertical distance between the two wings
Gap
The ratio between the shorter to the longer wing
Span Ratio
The longitudinal offset of the two wings relative to each other
Stagger
When upper wing is closer to the nose
Positive Stagger
When lower wing is closer to the nose
Negative Stagger
Relative incidence between the two wings
Decalage
When upper wing has a larger incidence
Positive Decalage
Rear section of the airfoil is hinged so that it can be rotated downward
Plain Flap
With a _____ flap, CLmax can be almost doubled
simple plain flap
Creates more lift simply by mechanically increasing the effective camber of the airfoil
Plain Flap
Increases the drag and pitching moment
Plain Flap
Only the bottom surface of the airfoil is hinged
Split Flap
Causes a slightly higher CLmax than that for
a plain flap
Split Flap
Performs the same function as a plain
flap, mechanically increasing the effective
camber
Split Flap
Produces more drag and less change in the pitching moment compared to a plain
flap
Split Flap
A small, highly cambered airfoil located
slightly forward of the leading edge of the
main airfoil
Leading Edge Slat
Essentially a flap at the leading edge, but
with a gap between the flap and the
leading edge
Leading Edge Slat
CLmax is increased with no significant
increase in drag
Leading Edge Slat
The slot allows the higher-pressure air on
the bottom surface of the airfoil to flow
through the gap, modifying and
stabilizing the boundary layer over the
top surface of the airfoil
Single-Slotted Flap
Higher CLmax compared to a single-slotted
flap
Double-Slotted Flap
This benefit is achieved at the cost of increased mechanical complexity
Double-Slotted Flap
Mechanically sucks away a portion of the
boundary layer through small holes or
slots in the top surface of the airfoiI
which delays flow separation
Boundary Layer Suction
Translates or tracks to the trailing edge of
the airfoil to increase the exposed wing
area and further increase lift
Fowler Flap
A leading-edge slat which is thinner, and
which lies flush with the bottom surface
of the airfoil when not deployed
Krueger Flap
The ______ exists mainly for trim, stability and control
empennage
Lightweight
Horizontal tail is in the wake of the wing
Does not allow for aft-mounted engine
Low horizontal tails are best for stall
recovery
Conventional
Heavier due to strengthening of the
vertical tail to support the horizontal tail
T-Tail
Allows for a smaller vertical tail due to
end plate effect
T-Tail
Horizontal tail is clear of wing wake and propwash
T-Tail
Allows for an aft-mounted engine
T-Tail
Most prone to Deep Stall, Where the wing blankets the Elevator causing a stall
T-Tail
Compromise between conventional and
T-tail
Cruciform
Less weight penalty compared to T-tail
Undisturbed flow in lower part of rudder
at high angles of attack
No endplate effect
Cruciform
Undisturbed flow in vertical tails at high
angles of attack
H-Tail
May enhance engine out control in
multiengine aircraft with the rudders
positioned in the propwash
H-Tail
Endplate effect on the horizontal tail;
reduced size possible
H-Tail
Heavier than conventional
Hides hot exhaust from heat seeking
missiles
H-Tail
Allows for smaller/shorter vertical tail
H-Tail
May allow for a reduced wetted area
Reduced interference drag
V-Tail (Butterfly)
Control/Actuation complexity
Adverse roll-yaw coupling
Surfaces are out of the wing wake
V-Tail (Butterfly)
Proverse Roll-Yaw Coupling
Reduced spiraling tendencies
Ground clearance problems
Inverted V-Tail
Avoids complexity of ruddervators
V surfaces provide pitch control only
Rudder in third surface
Y-Tail
Avoids blanketing of the rudders due to
wing and forward fuselage at high angles
of attack
Twin Tails
Reduces height; area is distributed between the two vertical tails
Usually heavier than a single centerline
mounted vertical tail
Twin Tails
Allows for a pusher propeller
configuration
are typically heavier than a
conventional fuselage construction
May be connected or not; high-, mid-, or
low-mounted horizontal tail, which can
have a V configuration
Boom-Mounted Tails
Doubles as a propeller shroud
Conceptually appealing, however proven
inadequate in application
Ring Tail
Negligible contribution to lift
Used to control angle of attack of wing
Used to balance pitching moments due to
flaps
Control Canard
Contributes to lift; higher aspect ratio for
reduced induced drag; greater camber for
increased lift
Pushes wing aft; bigger pitching moments
due to flaps
Canard is closer to CG; less effective pitch
control; surface must be increased;
resulting in more trim drag
Pitch up tendencies are avoided
Lifting Canard
50% theoretical reduction in induced drag
because lift is distributed between the
two wings
Aft wing experiences downwash and
turbulence caused by the forward wing
Wings must be separated as far as
possible
Tandem Wing
Theoretically offers minimum trim drag
Additional weight; more interference
drag; complexity
Three Surface
Incorporated into a faired extension of
the wing or fuselage
Used to prevent pitch up but can also
serve as a primary pitch control surface
Back Porch/Aft-Strake
Offers the lowest weight and drag
Reduced wing efficiency
Most difficult configuration to stabilize
Tailless
Drag of the proposed installation
Accessibility and Maintainability
The vertical and/or lateral location of the
thrust line(s) are critically important in
this respect
Weight and balance consequences of the
proposed installation
Inlet requirements and resulting effect on
‘installed‘ power and efficiency
Acceptable FOD characteristics
Geometric clearance when static on the
ramp:
o No nacelle or propeller tip may
touch the ground with deflated
landing gear struts and tires
Geometric clearance during take-off
rotation:
o No scraping of nacelles or of
propeller tips is allowed with
deflated landing gear struts and
tires
Geometric clearance during a low speed
approach with a 5 degrees bank angle
No gun exhaust gases may enter the inlet
a jet engine
ENGINE DISPOSITION CONSIDERATIONS
a) Wing-Mounted
b) Fuselage-Mounted
c) Empennage-Mounted
d)Any Combination of the Above
WING MOUNTING
The vector sum of the rotational speed
and the aircraft’s forward speed
Tip Speed
PROPELLER DIAMETER
𝑑 = 22 4^√𝐻p
Two Blade
PROPELLER DIAMETER
𝑑 = 18 4^√𝐻P
Three Blade
PROPELLER DIAMETER
𝑑 = 20 4^√𝐻P
Three Blade (Agricultural)
The propeller or inlet plane is forward of
the CG
There is a more effective flow of cooling
air for the engine
Tractor
Tend to be destabilizing with respect to
static longitudinal and directional stability
Tractor
The propeller is working in an
undisturbed free stream
Tractor
The propeller slipstream disturbs the
quality of the airflow over the fuselage
and wing root
Tractor
The propeller or the inlet plane is located
behind the CG
Tend to be stabilizing
May save empennage area
Pusher
Allows a shorter fuselage, hence smaller
wetted surface area
Higher-quality (clean) airflow prevails
over the wing and fuselage
Engine noise in the cabin area is reduced
Pusher
The pilot’s front field of view is improved
Propeller is more likely to be damaged by
flying debris at landing
Engine cooling problems are more severe
Pusher
PROPELLER CLEARANCES
Tricycle
7 inches
PROPELLER CLEARANCES
Conventional
9 inches
PROPELLER CLEARANCES
Over Water
18 inches
Employed by many sailplanes for its
simplicity
Single Main
Flat attitude take-off and landing
Aircraft must have high lift at low AOA
(high AR with large camber and/or flaps)
Bicycle
Used by aircraft with narrow fuselage and
wide wing span
CG should be aft of the midpoint of the 2
wheels
Bicycle
More propeller ground clearance
Less drag and weight
Easier lift production due to attitude,
hence initial AOA
Conventional/Tail Dragger
Inherently unstable (ground looping)
Limited ground visibility from cockpit
Inconvenient floor attitude
Conventional/Tail Dragger
Stable on the ground; can be landed with
a large “crab angle” (nose not aligned
with runway)
Improved forward ground visibility
Tricycle
Flat cabin floor for passenger and cargo
loading
Tricycle
Flat take-off and landing attitude
Permits a very low cargo floor
Quadricycle
For extra heavy aircraft (200-400 kips)
Redundancy for safety
Multi-Boogey
Maximum load anticipated in service
Limit or Applied Load
Maximum load, which a part of structure
is capable of supporting
Design or Ultimate Load
𝐷𝑒𝑠𝑖𝑔𝑛 𝐿𝑜𝑎𝑑 = 𝐿𝑖𝑚𝑖𝑡 𝐿𝑜𝑎𝑑 × 𝐹. 𝑆.
Design or Ultimate Load
Factor which the limit load must be
multiplied to establish the ultimate load
Normally 1.5 unless otherwise specified
Factor of Safety
Load factor corresponding to limit loads
Limit Load Factor
Load Factor corresponding to ultimate
load
Ultimate Load Factor
Ratio of the specified load to the total
weight of the aircraft
Load Factor
Greatest air loads on an aircraft usually
come from the generation of lift during
high maneuvers
Aircraft load factor expresses
maneuvering of an aircraft as a multiple
of the standard acceleration due to
gravity g(32.174 ft/sec2)
Maneuver Loads
At lower speeds, the highest load factor
an aircraft may experience is limited by
the maximum lift available
At Higher Speeds the maximum load
factor is limited to some arbitrary value
based upon the expected us of the
aircraft
Maneuver Loads
-The loads experienced when the aircraft
encounters a strong gust can exceed
maneuver loads in some cases
-When an aircraft experiences a gust, the
effect is an increase (or decrease) in
angle of attack
Gust Loads
Maneuvering Load Factors
For Normal Category
2.5 < 𝑛 < 3.8
Maneuvering Load Factors
For Utility Category
2.5 < 𝑛 < 4.4
Maneuvering Load Factors
For Acrobatic Category
2.5 < 𝑛 < 6.0
Negative limit Maneuvering Load Factor
Should not be less than
-0.4n
Normal and Utility
Negative limit Maneuvering Load Factor
Should not be less than
-0.5n
Acrobatic
Obtained in a pullout at the highest
possible angle of attack on the wing
The lift and drag forces are perpendicular
and parallel respectively to the relative
wind
Positive High Angle of Attack
Occurs in intentional flight maneuver in
which the air loads on the wing are down
or when the airplane strike suddenly
downwards while in level flight
Negative High angle of Attack
The wing has the smallest positive angle
at which the lift corresponding to the
limit-load factor may be developed
Positive Low Angle of Attack
Occurs at the diving-speed limit of the
airplane
Occurs in an intentional maneuver
producing a negative load factor or in a
negative gust condition
Negative Low Angle of Attack
AIRPLANE CATEGORIES
Limited to airplanes that have a seating
configuration, excluding pilot seats, of
nine or less, a maximum certificated takeoff of 12,500 pounds or less
Intended for non-acrobatic nonscheduled passenger, and non-scheduled
cargo operation
Limited to:
o Any maneuver incident to
normal flying
o Stalls except whip stall
o Lazy eights, chandelles, and
steep turns, in which the angle
of bank is less than 60°
Normal Category
AIRPLANE CATEGORIES
Limited to airplanes that have a seating
configuration, excluding pilot seats, of
nine or less, a maximum certificated takeoff weight of 12,500 pounds or less
Intended for Normal operations and
limited acrobatic maneuvers
Not suited for snap or inverted
maneuvers
Used in operations covered under the
normal and limited acrobatic operations
Limited to:
o Spins
o Lazy eights, Chandelles, and
steep turns, in which the angle
of bank is more than 60° but
less than 90°
Utility Category
AIRPLANE CATEGORIES
Limited to airplanes that have a seating
configuration, excluding pilot seats, of
nine or less, a maximum certificated take-off weight of 12,500 pounds or less
Have no specific restrictions as to type of
maneuvers permitted unless the
necessity therefore is disclosed by the
required flight test
Acrobatic Category
AIRPLANE CATEGORIES
limited to propeller-driven, multiengine
airplanes that have a seating
configuration, excluding pilot seats, of 19
or less, and a maximum certificated takeoff weight of 19,000 pounds or less
Cannot be type certificated with other
categories on a single airplane
Limited to:
o Normal flying
o Stalls (except whip stalls)
o Steep turns, in which the angle
of bank is not more than 60°
Commuter Category
LIMITED ACROBATIC MANEUVERS
The degree of back varies from 45 to 75°
Steep Turn
LIMITED ACROBATIC MANEUVERS
If done intentionally and a flight condition
if it occurs, which is a result of a complete
stall after which the airplane, still in
stalled altitude, loses altitude rapidly and
travels downward in a vertical helical or
spiral path
Spin
LIMITED ACROBATIC MANEUVERS
Airplane is operating at an angle of attack
of maximum lift
Loss of flying speed and in many cases
temporary loss of lift and control
Stall
LIMITED ACROBATIC MANEUVERS
The result of a complete stall in which the
nose of the airplane whips violently and
suddenly downward
In some cases, The airplane slides
backward a short distance before the
nose of the plane drops
Causes severe strains on the engine
mounts and all surfaces
Whip Stall
LIMITED ACROBATIC MANEUVERS
Combines the dive, turn and the climb
The nose of the airplane describes a
horizontal figure eight lying on its side
upon the horizon
Lazy Eight Flight
LIMITED ACROBATIC MANEUVERS
Maneuver of the composite type,
combining climb and turn, approach to a
stall and recovery back to normal flight
Chandelle
WING SPAR LOCATION
15-30% of the chord
Front Spar
WING SPAR LOCATION
65-75% of the chord
Rear Spar
WING RIBS SPACING
Light Airplanes
36 inches
WING RIBS SPACING
Transports
24 inches
WING RIBS SPACING
Fighters and Trainers
Vary Widely
EMPENNAGE SPAR LOCATION
Front Spar
15-25% of the chord
EMPENNAGE SPAR LOCATION
Rear Spar
70-75% of the chord
EMPENNAGE RIBS SPACING
Light Airplanes
15-30 inches
EMPENNAGE RIBS SPACING
Transports
24 inches
EMPENNAGE RIBS SPACING
Fighters and Trainers
Vary Widely
