Basic Aerodynamics& Theory of Flight
ByAhmad Ahsan
Course Grading
Marks Distribution
Aircraft Structure• Aircraft structure is required to support two types of
load• Ground Load: movement on the ground ( taxiing,
landing, and towing)• Air Loads: loads during flight by maneuvers and
gusts • Function of Aircraft Structure:• To transmit and resist loads.• To provide and maintain shape.• To protect passengers, payload, and systems from the
environmental conditions.
A. Fuselage
B. Wings
C. Empenage or
Tail
D. Power Plant
E. Landing Gear or
Undercarriage
Aircraft Components
Propeller
Landing Gear
Wing
Left Aileron
Fuselage
Empennage
Nacelle
Right Aileron
WingHorizont
al Stabilize
r
Vertical Stabilize
r
Rudder
Elevator
Main body of airplane Pilot & cargo compartments Generally constructed in two or more sections Carries accessories and other equipments Includes numerous access doors, inspection plates,
landing wheel wells, and other openings
Fuselage
• Airfoils attached to each side of the fuselage
• Main lifting surfaces
• Various design size and shape
• May be attached at the top, middle, or lower
portion of the
fuselage
- High-wing, mid-wing, and low-wing
• The number of wings can also vary
- Monoplanes, biplanes
Wing
Know n as tail section
Consist of
◦ Vertical Stabilizer
◦ Rudder
◦ Horizontal Stabilizer
◦ Elevators
Empennage - Tailplane
Power PlantA unit or machine that converts chemical energy
contains in the fuel to thrust force. Thrust force is
essential for moving the airplane forward and
producing lift force. With the piston engine, the
propeller is used to convert torque at engine shaft to
be thrust.
With the jet engine,
the jet engine
output is the
thrust force.
Located underneath of the
fuselage with shock strut
Fixed / Retractable
Provides means of landing taxiing
Tri- cycle –Conventional type
Floating gear for seaplane /ski-
equipped for ice surface landing
etc..
Landing Gear
Material use in Airframe Construction
Airframe Materials Properties
- High Strength to Weight ratio
- Light weight
- Corrosion Resistant
- Should be non flammable
- High quality
• WOOD
• STEEL & ITS ALLOYS (Strong)
• ALUMINIUM & ITS ALLOY (Commonly used)
• TITANIUM ALLOYS (Heat Barriers)
• MAGNESIUM ALLOYS (light and strong)
• PLASTICS & COMPOSITE MATERIAL (modern
and latest)
Material use in Airframe Construction
Fuselage Structure DetailTYPES OF STRUCTURETYPES OF STRUCTURE
TRUSS TYPE
- PRATT TRUSS
- WARREN TRUSS
MONOCOQUE
SEMI-MONOCOQUE
TRUSS TYPE
• Most early aircraft used this technique with
wood and wire trusses.
• The truss type fuselage frame is assembled with
members forming a rigid frame e.g. beams, bars, etc
• There are two types of truss structure.
- PRATT TRUSS
- WARREN TRUSS
PRATT TRUSSPRATT TRUSS• Early aircraft
• Wooden or metal
structure
• Heavy weight
• Box like structure
Diagonal members of tubing or solid rods
• Conical Type structure• Force transfer to other supporting beams• Capable to carry tension + compression• More space , strength , rigidity• Better streamline
WARREN TRUSSWARREN TRUSS
MONOCOQUE MONOCOQUE • In this method, the exterior surface of the fuselage is
the primary structure.
•A later form of
this structure uses
fiberglass cloth
impregnated with
polyester or epoxy
resin, instead of
plywood, as the skin.
MONOCOQUE MONOCOQUE
SEMI-MONOCOQUESEMI-MONOCOQUE•This is the preferred method of constructing an all-
aluminum fuselage.
•Includes a series of frames in the shape of the
fuselage cross sections are held in position on a
rigid fixture, or jig.
•These frames are then joined with lightweight
longitudinal elements called stringers.
•These are in turn covered with a skin of sheet
aluminum, attached by riveting or by bonding with
special adhesives.
SEMI-MONOCOQUESEMI-MONOCOQUE
Fuselage Sections are joined by usingfasteners.Fuselage Sections are joined by usingfasteners.
Basic TermsVertical Members :
• Formers: a structural member of an aircraft
fuselage, of which a typical fuselage has a
series from the nose to the empennage.
• Typically perpendicular to the longitudinal axis
of the aircraft.
• The primary purpose of formers is to establish
the shape of the fuselage, reduce the length
of stringers, and prevent instability.
Basic TermsVertical Members :
• Frame : The mechanical structure of the
aircraft including its fuselage, wings, and
empennage.
• Bulkhead : A dividing wall within an aircraft or
ship.
Longitudinal Members
• Longerons : longitudinal structural component
of an aircraft's fuselage usually along the
length of fuselage.
• Stringers : longitudinal structural components
between sections of
fuselage.
Wing Structure•In most modern airplanes, the fuel tanks are an
integral part of the wing structure, or consist of
flexible containers mounted inside of the wing.
• Attached to the rear, or trailing, edges of the wings
are two types of control surfaces referred to as
ailerons and flaps.
Empennage•The empennage includes the entire tail group,
consisting of fixed surfaces such as the vertical
stabilizer and the horizontal stabilizer.
•The movable surfaces include the rudder, the elevator,
and one or more trim tabs.
• A second type of empennage design includes a one-
piece horizontal stabilizer that pivots from a central
hinge point. ( called stabilator )
•The rudder is attached to the back of the vertical
stabilizer.
•Trim tabs are small, movable portions of the trailing
edge of the control surface. These movable trim
tabs, which are controlled from the cockpit, reduce
control pressures. Trim tabs may be installed on
the ailerons, the rudder, and/or the elevator.
Empennage Structure
Spar
RibsStringers
Skin
Spar
Stringers
Stabilator
•The landing gear is the principle support of the
airplane when parked, taxiing, taking off, or when
landing.
•The most common type of landing gear consists of
wheels. T
•The landing gear consists of three wheels — two
main wheels and a third wheel positioned either at the
front or rear of the airplane.
Landing Gear Structure
Landing Gear Types
Landing Gear Types: Tricycle, Tailwheel, Bogey
Landing Gear Types
Landing Gear Types
Other Landing Gear Types : Float & Ski
•The power plant usually includes both the engine and
the propeller. •The primary function of the engine is to provide the
power to turn the propeller. •It also generates electrical power, provides a vacuum
source for some flight instruments, and in most single-
engine airplanes, provides a source of heat for the
pilot and passengers. •The engine is covered by a cowling, or in the case of
some airplanes, surrounded by a nacelle. •The purpose of the cowling or nacelle is to streamline the
flow of air around the engine and to help cool
engine.
Power Plant
• Wing Pod Mount – Commonly use on commercial airplane since fuel is
carried in wing– Less noise– Bad yawing moment effect– Ground clearance limitation higher gear strut
• Clean wing , shorter take off.• No ground clearance limitation• Less yawing effect• Weight penalty Aft Cg. and load distribution • Cabin Noise and Vibration• Fuel pump
Fuselage Mount
• “Any surface, such as a wing, propeller, rudder, or even a trim tab, which provides aerodynamic force when it interacts with a moving stream of air.” FAA
•The mean camber line is a line drawn midway between the upper and lower surfaces
• The chord line is a straight line connecting the leading and trailing edges of the airfoil.
The Airfoil
The angle of attack is the angle between the
chord line and the average relative wind.
Greater angle of attack creates more lift (up to a
point).
Angle of Attack
Bernoulli’s Principle & Airfoil• The upper surface of an
airplane’s wing is designed to have a greater curvature or camber as compared to lower surface. This greater curvature causes air to flow faster over the upper surface.
• Due to higher speed, the pressure decreases.
• On the lower pressure, the lesser curvature causes decrease in speed and increase in pressure.
• This creates “Lift”
Four Forces of Flight
DRAG
WEIGHT
THRUST
LIFT
Lift• Lift is the force created by the interaction between the wings
and the airflow. • It opposes the downward force of weight. • Lift is an aerodynamic force and is directly proportional to the
square of velocity. • It is produced by the dynamic effect of the air acting on the
airfoil. • It acts perpendicular to the flight path.• Aircraft lift acts through a single point
called the center of pressure. • Lift Equation: L=½ ρ V2A CL
LIFT
Weight• Weight is the combined load of the aircraft, crew, fuel,
passengers, and the cargo. • Weight pulls the aircraft downward because of the force of
gravity. • It opposes lift, and acts through the aircraft’s center of gravity
(CG)• Weight is not constant
WEIGHT
Thrust• Thrust is the forward force produced by the
powerplant,propeller or rotor. • It opposes or overcomes the force of drag.• Direction of thrust depends on design
THRUST
Drag• Drag is a rearward acting force that resists the motion of
aircraft through the air.• It is an aerodynamic force and like lift varies to square of
velocity.• Two broad drag classifications.• Parasite drag: caused by disruption of airflow by the wing,
rotor, fuselage, and other parts of structure. • Induced drag: produced as reaction of lift• Drag Equation: D= ½ ρ V2A CD
DRAG
The Ailerons control movement on the lateral axis called
“rolling”.
Control around the Longitudinal AxisAssignment
The End