Introduction

to Aircraft
Engineering
Unit 1
History and Aircraft Configurations
• A short history: The history of aeronautics has
extended over more than two thousand years.
• The earliest attempts begin with the kites and gliders,
Early air vehicles
and continued with powered heavier than
air, supersonic and hypersonic flight.
• The first form of man-made flying objects was kites.
• The earliest known record of kite flying is from around
200 BC in China.

• Then it was the time of balloons, ancient European

kingdoms support for the design of new concepts of
balloons.

• In December 1903 that laws of flight were finally given

by human beings to a degree sufficient to allow a heavier
than air, powered, human carrying machine to execute a
successful sustained flight through the air. December 17,
1903 at 10.35 is ORVILLE and WILLOUR WRIGHT flied the
first successful flying machine at KILL DEVIL HILLS, North
Carolina.
• Before the Wright brothers first flight,
there were no successful airplane designs,
hence no successful demonstration of
airplane performance, however there were
plenty of attempts.

• All early thinking of human flight

centered on the imitation of birds. Various
unsung ancient people fashioned wings and
always unsuccessful consequence in leaping
from towers or flapping vigorously.

• It was replaced by the concept of wings

flapped up and down by various mechanical
mechanisms powered by same type of
human arm, leg or body movement. These
machines are called “ORNITHOPTERS”.
The Dawn of Flight-

• KITE
1. A journey into the skies began in the
5th century with the invention of kites in
ancient China.

2. Kites served as both art and science,

capturing the imagination of
civilizations.

3. They were essential for understanding

aerodynamics and controlled flight.

4. This marked the starting point of

humanity's fascination with flight.
Leonarda da vinci: Designed Nemours such ornithopters in the period from 1486-1490.

Leonarda da vinci made the first real studies of flight in the 1480’s. He had over 100
drawings that illustrated theories on flight. The ornithopters flying machine was never
actually created it was a design that Leonarda da vinci created to show how man could fly.
The modern day helicopter is based on this concept.
 Sir George cayley (1773-1857) - The true
inventor of the airplane.
• George cayley worked to discover a way that man
could fly.
• He designed many different versions of gliders that
used the movements of the body to control.
• He changed the shape of the wings so that the air
would flow over the wings correctly.
• He designed a tail for the gliders to help with the
stability.
• He tried a biplane design to add strength to the glider.
• He also recognized that there would be a need for
power if the flight was to be in the air for a long time.
William Samuel Henson
William Samuel Henson (3 May 1812 – 22
March 1888) was a British-born pre-Wright
brothers aviation pioneer, engineer and inventor.
He is best known for his work on the aerial
steam carriage alongside John Stringfellow.

Starting c. 1838, Henson became interested in

aviation.
In April 1841 he patented an improved
lightweight steam engine, and with fellow
lacemaking-engineer John Stringfellow in c.
1842 he designed a large passenger-carrying steam-
powered monoplane, with a wing span of 150 feet,
which he named the "Henson Aerial Steam
Carriage". He received a patent on it in 1843 along
with Stringfellow.
• Henson, Stringfellow, Frederick
Marriott, and D.E. Colombine,
incorporated as the Aerial Transit
Company in 1843 in England, with
the intention of raising money to
construct the flying machine.

• Henson built a scale model of his

design, which made one tentative
steam-powered "hop" as it lifted, or
bounced, off its guide wire.

• Attempts were made to fly the

small model, and a larger model with
a 20-foot wing span, between 1844
and 1847, without success.
 Felix du temple
• Félix du Temple de la Croix (18 July
1823 – 3 November 1890) was
a French naval officer and an inventor, born
into an ancient Norman family.

• He is widely credited with achieving the

first successful powered flight of a
heavier-than-air machine in 1874.

• He designed and built a monoplane that

was powered by a steam engine.

• Although the flight only involved a brief

glide after taking off from an inclined
ramp, this marked a significant step toward
powered flight.
• His aircraft was made of lightweight
materials, including aluminum, which
was an advanced choice for the time.

• Temple filed a patent in 1857 for an

aircraft design that combined the
elements of powered flight and gliders.

• His aircraft featured retractable landing

gear, a feature still common in modern
aircraft, showing his forward-thinking
approach to aviation design.

• His early attempt at powered flight was

a precursor to later breakthroughs by
pioneers such as the Wright brothers.
 Alexander Mozhauski
• Alexander Fedorovich Mozhaysky was an
admiral in the Imperial Russian
Navy, aviation pioneer, researcher and
designer of heavier-than-aircraft.

• In 1909 a Russian newspaper claimed

Mozhaysky's hop was the first powered
flight. This claim was later repeated in
many Soviet publications.

• In 1971-1981 Central Aerohydrodynamic

Institute researched the topic and disproved
the claim.
• His original aircraft was found incapable of
generating lift because of low engine
capacity.
• It was understood that with a more powerful
engine, which Mozhaysky had planned
shortly before his death, the aircraft might
have been able to fly.
• Nevertheless, Mozhaysky's aviation
achievements, particularly with
regard to flight
controls and propulsion, were
considerable given the limits of the
technology available to him.

• He was honored in Russia as a key

figure in the history of aviation.

• While his aircraft did not fly, his

innovative work represented an early
attempt at achieving controlled
powered flight and is seen as a
precursor to later advancements in the
field.
 Otto lilenthal (1848 – 1896 )-
the glider man
• Otto Lilienthal was born on May 23 1848 at
Germany, a germen mechanical engineer, also
called as glider man.

• He studied aerodynamics and worked to design a

glider that would fly.

• He was the first person to design a glider that

could fly a person and able to fly long distances.

• He was fascinated by the idea of flight. Based on

his studies of birds and how they fly, he wrote a
book on aerodynamics that was published in 1889
and this text was used by the wright brothers as
the basis for their designs.

• After more than 2500 flights, he was killed when

he lost control because of a sudden strong wind
and crashed into the ground.
Wright Brothers

Orville and Wilbur Wright were very

deliberate in their quest for flight. First,
they read about all the early developments
of flight.
They decided to make "a small
contribution" to the study of flight control
by twisting their wings in flight.

Then they began to test their ideas with a

kite. They learned about how the wind
would help with the flight and how it could
affect the surfaces once up in the air.
The next step was to test the shapes of
gliders much like George Cayley did
when he was testing the many different
shapes that would fly. They spent three
years testing and learning about how
gliders could be controlled at Kitty Hawk,
North Carolina.
They designed and used a wind tunnel to
test the shapes of the wings and the tails
of the gliders. In 1902, with a perfected
glider shape, they turned their attention to
how to create a propulsion system that
would create the thrust needed to fly.

The early engine that they designed

generated almost 12 horsepower. That's
the same power as two hand-propelled
lawn mower engines!
• The "Flyer" lifted from level ground to the north
of Big Kill Devil Hill, North Carolina, at 10:35
a.m., on December 17, 1903. Orville piloted the
plane which weighed about six hundred pounds.
 • The first heavier-than-air flight travelled
one hundred twenty feet in twelve seconds.
The two brothers took turns flying that day
with the fourth and last flight covering 850
feet in 59 seconds. But the Flyer was
unstable and very hard to control.

• The brothers returned to Dayton, Ohio,

where they worked for two more years
perfecting their design. Finally, on October
5, 1905, Wilbur piloted the Flyer III for 39
minutes and about 24 miles of circles around
Huffman Prairie. He flew the first practical
airplane until it ran out of gas.

https://www.youtube.com/watch?v=dtZ8MxuePno
1783 - Joseph and Jacques Montgolfier- the First Hot Air Balloon

• The brothers, Joseph Michel and Jacques

Etienne Montgolfier, were inventors of the
first hot air balloon.

• They used the smoke from a fire to blow hot

air into a silk bag. The silk bag was attached to
a basket. The hot air then rose and allowed the
balloon to be lighter-than-air.

• In 1783, the first passengers in the colorful

balloon were a sheep, rooster and duck. It
climbed to a height of about 6,000 feet and
traveled more than 1 mile.
• After this first success, the brothers
began to send men up in balloons.
The first manned flight was on
November 21, 1783, the passengers
were Jean-Francois Pilatre de Rozier
and Francois Laurent.
Types of flight
vehicles

Classifications
 Lighter than air aircraft:
➢ The first flying object
➢ Density is very less compare to the density of
air
➢ It easily float on the air
➢ They are airships, free balloons and kite
balloons

Working Principle:

Lighter-than-air (LTA) aircraft are vehicles that

remain buoyant and can fly by displacing air, using
a gas lighter than air, such as helium or hydrogen.

These aircraft rely on the principle of buoyancy

rather than generating lift through aerodynamic
forces like airplanes do.
Types of Lighter-than-Air Aircraft:

• Balloons:
• Hot air balloons: Heated air inside the
balloon provides lift.
• Gas balloons: Filled with lighter-than-air
gases like helium or hydrogen.

• Airships (Dirigibles):
• These are powered, steerable aircraft that can
navigate using propulsion systems. They
include rigid, semi-rigid, and non-rigid
airships (blimps).
• Kite:
• A kite is a tethered aircraft that flies by
harnessing wind power. It consists of a
lightweight frame, often covered with fabric
or paper, which is attached to a string or line.
Airships:
It is used for transportation in earlier days(19 century).

Nonrigid Airships (Blimps):

• These are essentially large gas-filled balloons
with a car (or gondola) attached by cables. The
gas inside provides the necessary buoyancy for
flight.
Feature: The airship's shape is entirely
dependent on the gas inside. If the gas escapes,
the entire balloon collapses because there is no
internal structure to maintain its form.

Example: Used for advertising or short-term

observational flights.
Semirigid Airships:
• A nonrigid airships in that they also rely on
internal gas for lift and shape, but they have an
additional feature—a metal keel or framework
running along the bottom of the airship.

• Feature: This keel adds structural support,

especially for the car or gondola (which carries
passengers or cargo). While the gas still
maintains most of the shape, the keel provides
some stability and support.
• The metal keel prevents the entire airship
from collapsing if some gas escapes, offering
more reliability than nonrigid airships.
 Rigid Airships:
Rigid airships have a solid internal structure made of a
lightweight material, like aluminum-alloy beams. This
structure is covered with fabric, but the fabric itself is
not airtight.

Feature: Inside the rigid framework are multiple gas-

filled balloons or cells. These individual gas cells can
be filled or emptied as needed to control the airship's
buoyancy.
Advantage: A rigid airship keeps its shape even if some or all of the gas escapes, because
the shape is maintained by the framework, not by the gas. This makes them more robust and
capable of handling larger payloads.

Example: The famous Zeppelins are examples of rigid airships, used for long-distance
travel and heavy lifting.
Free Balloon

A balloon is a lighter-than-air aircraft

that is not engine driven, and that
sustains flight through the use of
either gas buoyancy or an airborne
heater.
Kite Balloon
A kite balloon is a tethered balloon which is shaped to help make it stable in low and
moderate winds and to increase its lift. It typically comprises a streamlined envelope with
stabilizing features and a harness or yoke connecting it to the main tether and a second
harness connected to an observer's basket.
They can fly in higher winds than ordinary round balloons which tended to bob and spin in
windy conditions. They were extensively used for military observation during World War I
and similar designs were used for anti-aircraft barriers, as barrage balloons in both world
wars.
Heavier than Air (AERODYNE)
Engine Driven
i) Aeroplane

An airplane or aeroplane (informally plane) is a fixed-wing aircraft that is propelled forward by thrust from
a jet engine, propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing
configurations.

Amphibian plane Land Plane Sea Plane

ii) Rotary Wing Aircraft
A rotorcraft or rotary-wing aircraft is a heavier-than-air aircraft with rotary wings or rotor blades, which
generate lift by rotating around a vertical mast. Several rotor blades mounted on a single mast are referred to as
a rotor.

Helicopter
Gyroplane
iii) Ornithopters

An ornithopter (from Greek ornithos "bird" and pteron "wing") is an aircraft that flies by flapping its wings.
Designers seek to imitate the flapping-wing flight of birds, bats, and insects. Though machines may differ in
form, they are usually built on the same scale as these flying creatures. Manned ornithopters have also been
built, and some have been successful. The machines are of two general types: those with engines, and those
powered by the muscles of the pilot.
COMPONENTS OF FIXED WING AIRPLANE AND THEIR FUNCTIONS
Wing Configurations
Rectangular Tapered Elliptical Swept back

Swept forward Delta Complex Delta

Empennage or the tail of the airplane
 Design
Configuration
Conventional Configurations:

▪ Variations regarding
powerplant & intake location,
▪ Vertical wing position,
▪ Tail unit layout and
▪ Landing gear.

Unconventional Layouts:

▪ Biplanes,
▪ Variable sweep,
▪ Canard designs,
▪ Twin booms,
▪ Multi-hulls,
▪ Blended wing body designs.
Special Configuration in aircraft

▪ Short Take-Off & Vertical

Landing,
▪ Stealth,
▪ Waterborne
Conventional Configuration
in Aircraft

➢ Cantilevered monoplane wing.

➢ Separate horizontal and vertical tail
surfaces. Control via ailerons, elevators
and rudder.
➢ Discrete fuselage to provide volume and
continuity to airframe.
➢ Retractable tricycle landing gear.
➢ Minimum number of powerplants needed
to meet power and operational
requirements.
Conventional Configuration in Aircraft

Within the category of conventional aircraft there are many variations from the standard to
be considered:

➢ Powerplant Location – nose, wing podded, rear fuselage podded, internal.

➢ Intake Location – nose, side, ventral, dorsal.

➢ Wing Vertical Location – high, low, mid.

➢ Tail Unit Arrangements – variable incidence, all-moving, T-tail, multi-finned,

butterfly.

➢ Tricycle Landing Gear Configuration – numbers of legs, bogeys and wheels.

Powerplant Location:

Nose-Mounted

Most logical position for any single tractor propeller engine aircraft

Advantages include – symmetry of layout, good propeller clearance, access and

maintainability.
 Powerplant Location:
Wing-Mounted (Outer Wing)

Many uses:
➢ Large aircraft with propellers, turbojets or
turbofans.
➢ For jets/fans, these will be podded and
mounted onto under-wing pylons.
➢ For props, these will be mounted directly
Over/Under-wing Mounted - Examples
onto the wing structure.

Advantages include:
Versatility – use of alternative engines.
Compact overall layout.
Inertial relief – reducing required wing
structural mass.
Ease of access for maintenance.
Also several drawbacks and necessary considerations:

Ground clearance may be a problem in which case

high wings may be used (with tall landing gear) or
possibly top-wing mounting (e.g. BAe 748) with
aerodynamic penalty.

Spanwise location – should depend on propeller

diameter or statistical analysis of fan burst trajectory
and impact on neighbor.

Typical values are 30% and 55% semi-span for a 4-

Over/Under-wing Mounted - Examples
engine design; large values give big engine-out yaw
problems and larger rudder sizes.
Power plant Location

Integrated into Wing

• Mounting an aircraft's power plant (engines)

integrated into the wing, also known as
embedded engines, refers to the placement of
engines within the wing structure, as opposed
to the more common practice of mounting
engines on pylons beneath the wings.

• While this design concept has been explored

in various experimental aircraft, it is less
common in commercial aviation due to
engineering and operational challenges.
 Lower Noise Levels:
• With engines embedded in the wing, noise levels in the passenger cabin
can be reduced, as the engine is enclosed within the airframe, providing
additional sound insulation compared to traditional under-wing engine
mounts.

Advantages Structural Efficiency:

• Integrating the engines into the wing can reduce the need for heavy
of Integrating pylons and mounting structures, which might decrease the aircraft’s overall
structural weight.
Power Plants Protection from Ground Hazards:
into the • Since the engines are inside the wing, they are better protected from
potential foreign object damage (FOD) during takeoff and landing, as there
Wing: are no exposed engine nacelles that could be impacted by debris on the
runway.

Improved Wing Lift:

• Without external engine nacelles disrupting the airflow over the wing, the
lift-to-drag ratio of the wing can be improved, enhancing the overall
aerodynamic efficiency of the aircraft.
 Maintenance and Accessibility Challenges:
• One of the biggest drawbacks of integrating engines into the
wing is the complexity of maintenance. External engines are easier
to access for routine checks, repairs, or engine swaps, whereas
embedded engines would require more significant disassembly of
Disadvantage the wing structure, increasing maintenance time and costs.

s of Structural Complexity:
• Integrating engines into the wing requires reinforcing the wing
Integrating structure to handle the additional stresses of housing and operating
Power Plants the engines. This can increase the overall weight of the aircraft and
complicate wing design, potentially offsetting some of the
into the aerodynamic benefits.

Wing: Fuel Tank Design Limitations:

• Most aircraft wings house fuel tanks, and embedding engines
into the wings can reduce the available volume for fuel storage.
Designers would need to balance engine placement and fuel
capacity, which could limit the range or performance of the
aircraft.
Power plant Location

Buried in wings

B-1 Lancer

DeHavilland Comet
Powerplant Location

Rear Fuselage-Podded

Used on many moderate sized transport aircraft of the past and also many modern small
business jet aircraft.

Advantages

Reduced engine-out yaw smaller rudder size.

Disadvantages

Rearwards movement of CG stability problems.

Structural acoustic fatigue.

Difficult to inspect during turn around time.

 Example of Aircraft Engine Located Above the Fuselage

Due to the PiperJet’s unique engine installation

in the tail, ground personnel can walk around
the aircraft without being exposed to its jet
blast.

With the engine thrust line well above the

aircraft’s center of gravity, Piper engineers
worked on developing a system that
automatically compensates horizontal stabilizer
position for the changing pitching moments
introduced through changes in engine power.
Advantages of Aircraft Engines Located Above the Fuselage:
Noise Reduction in Cabin:

The positioning of engines above the fuselage can help to reduce cabin noise, as the engines
are farther from the passenger compartment compared to traditional under-wing
configurations.

Improved Ground Clearance:

Placing the engines above the fuselage provides greater ground clearance, making the
aircraft less susceptible to foreign object damage (FOD) during takeoff and landing,
especially on rough or unpaved runways.

Enhanced Safety for Water Landings:

For aircraft designed with amphibious capabilities or those likely to operate near water, such
as seaplanes, having engines located above the fuselage reduces the risk of engine water
ingestion during water landings or taxiing.
Efficient Wing Aerodynamics:
•Without engines mounted under the wings, designers can optimize wing design for better
aerodynamics, potentially improving fuel efficiency.
Disadvantages of Aircraft Engines Located Above the Fuselage:
Increased Drag:
•Mounting engines on top of the fuselage can create more aerodynamic drag compared to
engines mounted under the wings, which may reduce fuel efficiency.

Weight Distribution Challenges:

•Placing engines high on the fuselage can shift the center of gravity, leading to challenges in
weight balance. This may require compensations in aircraft design to maintain stability and
control.

Engine Installation Complexity:

•The structural design of the fuselage must be reinforced to handle the stresses and vibrations
of engines mounted above, potentially increasing the aircraft’s structural complexity and
weight.
Powerplant Location
Wing-Podded vs. Fuselage-Podded
Wing-Podded vs. Fuselage-Podded
Wing-Podded vs. Fuselage-Podded
Powerplant Location:- Internally Housed

Used on many single and twin turbojet/turbofan engine aircraft such as military trainers
and fighters.

Advantages:

➢ Compact layout.
➢ Reduced drag.

Disadvantages:

➢ Engine removal and maintenance problems.

➢ Structural acoustic fatigue due to jet efflux.
➢ Jet pipe length minimized by moving engine rearwards but this affects CG, stability
and control
Air Intake Location in
aircraft

• A nose intake is an aircraft

engine air intake located at the
front of the fuselage or the nose of
the aircraft.

• This design is primarily used in

jet aircraft, particularly military
fighters and supersonic aircraft,
where aerodynamic efficiency and
engine performance are critical.
 Advantages of a Nose Intake in Aircraft:

Efficient Airflow:
•A nose intake provides a direct, unobstructed path for air to enter the engine, especially
during high-speed flight. This ensures optimal airflow into the engine, which is critical for
maintaining engine performance at various speeds, including supersonic flight.

Improved Engine Performance:

•Since the intake is located at the front of the aircraft, it is not affected by turbulent airflow
around other parts of the airframe (like wings or fuselage). This results in smoother, more
efficient air ingestion into the engine, improving overall engine efficiency and thrust.

Simplified Design for Single-Engine Aircraft:

•For single-engine aircraft, the nose intake provides a straightforward solution for routing
air to the engine. It eliminates the need for complex ductwork, as seen in designs where
engines are mounted on wings or the rear of the fuselage.
Disadvantages of a Nose Intake:
Limited Placement Options for Equipment:
•A nose intake can limit the available space in the nose for other essential aircraft
components, such as radars or avionics systems. For military aircraft, this is a significant
drawback, as the nose is a prime location for radar antennas (as seen in most modern
fighter jets).

Risk of Foreign Object Damage (FOD):

•Since the nose intake is at the front of the aircraft and closer to the ground during takeoff
and landing, it is more exposed to debris on the runway. Foreign objects like stones or
loose debris can be ingested into the engine, potentially causing damage or failure.

Increased Noise in Cockpit:

•Having an intake so close to the cockpit can lead to increased noise and vibration levels
for the pilot, which may reduce comfort and necessitate additional soundproofing
measures. In long-duration flights, this can lead to pilot fatigue and require ergonomic
solutions.
Limited to Certain Aircraft Designs:
•Nose intakes are mainly feasible for single-engine designs or aircraft with engines placed
near the fuselage. They are not suitable for twin-engine aircraft .

•This limits the use of nose intakes to specific military or experimental aircraft
configurations.
 Intake Location

Side Intake (Below Wing)

• Used on the majority of modern high-

wing strike and combat aircraft
designs.
• Leaves the nose area free for radar
equipment installation.
• The wing is often extended above the
intakes to improve high- performance.
• Flow diverters are needed to
accommodate fuselage boundary layer Tornado F2
growth.
Dassault Breguet F1 Mirage
 Intake Location

Side Intake (Above Wing)

• Used on many low-wing design trainer and combat aircraft.

• Wings may be used to shield the intakes and reduce the maneuvering .

• Any sharps bends have to be avoided to prevent flow distortions.

• Short intake lengths are possible with low overall volume requirements.
 Intake Location
Ventral Intakes

Situated on underside of fuselage - an increasingly common position for high

performance combat aircraft.

Advantages

➢ Gives very good high-α maneuverability.

➢ Low flow distortion and pressure losses into intake.

Dis-advantages

➢ Prone to FOD and debris ingestion.

➢ Complicates nose wheel positioning/stowage.

➢ Restricts carriage of under-fuselage stores.

F16 Falcon
Intake Location
Dorsal Intake

➢ Situated on top-side of fuselage.

➢ Only tends to be used on 3-engine airliners with 3rd engine buried in the rear
fuselage/fin area with a few exceptions.

➢ Gives poor performance at high- α due to separated flow ahead of intake.

 Vertical Location of Wing

High Wing

Gives an efficient spanwise lift distribution leading to low lift-induced drag.

Improves lateral static stability.

Preferred for most freight and military transport aircraft:

➢ Low floor line for easy loading & unloading.

➢ Good all-round vehicular access when on ground.
➢ Wing fuel load away from ground when landing with failed landing gear.
➢ Good ground clearance for powerplants, especially props.
C-17_Globemaster
 Vertical Location of Wing
Low Wing

➢ Improves lateral manoeuvrability.

➢ Preferred for most passenger transport aircraft.
➢ Wing structure conveniently passes below floor.
➢ Volume free fore and aft of wing structure for cargo holds, luggage and landing
gear stowage.
➢ Minimizes landing gear length and mass.
➢ Wing provides buoyancy when ditching into water and also a platform for
emergency evacuation.
 Vertical Location of Wing
Mid Wing
Advantages of Mid-Wing Aircraft:

Aerodynamic Efficiency: Mid-wing designs can provide better aerodynamic efficiency

at various speeds, allowing for improved performance in cruise flight.

Improved Ground Clearance: Mid-wing designs often provide better ground clearance
than low-wing aircraft, which can be beneficial for operations on rough terrain or during
takeoff and landing.

Improved Maneuverability: The placement of the wings near the center of gravity
enhances the aircraft’s maneuverability and control responsiveness. This is especially
beneficial for military aircraft and aerobatic planes that need to perform rapid and precise
maneuvers, as it allows the pilot to maintain better control during complex movements.
Disadvantages of Mid-Wing Aircraft:

1. Complexity in Design: The structural requirements for mid-wing designs can be

more complex, potentially leading to increased weight or cost in construction.

2. Reduced Visibility: Pilots may have limited visibility compared to high-wing

designs, especially when it comes to ground operations or during certain maneuvers.

3. Less Natural Stability: While they do offer stability, mid-wing aircraft may not
have the same inherent lateral stability as high-wing designs, requiring more
attention from the pilot.

4. Reduced Cabin Space:The placement of the wings in the middle of the fuselage
often intrudes into the cabin space. This can be a disadvantage in larger commercial
or transport aircraft because the wing spars take up internal space, making it harder
to accommodate passengers or cargo efficiently.
Mid Wing
Aero Design DG-1

Republic F-84F Thunderstreak

 Tail Unit (Empennage)

Conventional Layout

➢ Approximately 70% of aircraft in service have a “conventional” arrangement

comprising separate fixed horizontal stabilizer and vertical fin surfaces for stability
and moving elevator and rudder sections attached to fixed surfaces for control.

➢ This is the simplest solution & provides optimum overall performance in the
majority of cases.
Conventional Layout
 Tail Unit (Empennage)

Variable Incidence Tailplane

➢ Here the forward (main) section of the horizontal surface is not fixed but is capable
of rotation through a small range of angles of attack.

➢ As such, it is generally used to adjust pitch trim rather than using the conventional
elevators.

➢ It is especially useful for countering the effects of significant pitching moment

increments caused by deployment of powerful high lift devices.

➢ Elevators are still used for pitch control.

Vought F-8 Crusader

Mooney airplanes:
 Tail Unit (Empennage)

All-Moving (Slab) Tailplane

➢ Whole of the horizontal tailplane surface is used for both pitch control and trim
(with no separate hinged elevator).

➢ This offers significant advantages at transonic and supersonic speeds when

effectiveness of conventional trailing edge surfaces is dramatically reduced.

➢ Universally adopted for supersonic fighter designs.

➢ Most also use differential movement of opposite sides to improve roll rate (then
known as tailerons).

➢ Powered controls are necessary due to the large control force requirements.
 Tail Unit (Empennage)

T-Tail

➢ Horizontal tailplane mounted on top of fin.

➢ Often used on large high-mounted sweptwing designs and also smaller

low-wing aircraft.
T-Tail - Advantages

➢ Provides substantial “end-plating” effect to fin, improving its effectiveness and reducing
the fin size requirement.

➢ Lifts the horizontal tail clear of any propwash & the wing wake during cruise flight,
therefore reducing buffet and fatigue.

➢ Allows engines to be mounted on the aft-fuselage, if required.

T-Tail - Disadvantages

➢ Gives a large mass penalty to the empennage due to the higher loading and aeroelastic
effects.
➢ Increased likelihood of “deep stall” – puts tail in wake of stalled wing, making
recovery difficult or even impossible.
 Tail Unit (Empennage)
Multi-Finned

➢ If fin-sizing exercise results in large single fin dimensions then sometimes preferable
to use two (or more) smaller fins instead.

➢ Allowed Constellation to operate from existing hangars.

➢ Also produces desirable “end-plating” effect to horizontal tailplane, reducing its size
requirements.

➢ Fins have to be positioned far enough apart so that undesirable mutual aerodynamic
interference effects are not too severe.

➢ Not generally used nowadays for single-boom layout transport aircraft.

 Tail Unit (Empennage)

Twin Fin Fighter Aircraft

➢ Twin fins nowadays more associated with supersonic fighters.

➢ More compatible with twin-engine aircraft (F14/F15/F18) than single (F16) due to
“engine-out” sizing considerations.

➢ Can also provide infrared shielding of engine exhaust to improve stealth, especially if
canted (F22).

➢ Resultant reduced fin height improves aeroelastic behavior.

F-22 Raptor
 Tail Unit (Empennage)
V-Tail

➢ In this case the conventional tail surfaces are combined into a pair of inclined
surfaces.
➢ The separate roles of the tailplane/elevator and fin/rudder are combined.

Advantages include:

Less interference drag; smaller total surface area; improved stealth characteristics.

Disadvantages include:

Cross-coupling of stability/control characteristics; handling difficulties; need for fully

automatic flight control system
LOCKHEED F-117 NIGHTHAWK

BEECHCRAFT BONANZA 35
 Landing Gear Layout

Tricycle Gear Configuration

The most conventional, comprising:

➢ Pair of main legs behind aircraft CG.

➢ Single nose leg ahead of CG.

Each leg incorporates:

➢ Shock absorber to dissipate vertical landing energy.

➢ Single or two side-by-side wheels or multiple bogie arrangement.

➢ Only main wheels are generally fitted with brakes.

Tricycle Gear Configuration – Further Comments

➢ Only the nose wheel is usually steered for ground maneuvering.

➢ For effective steering, nose leg should support between 6 and 10% of the aircraft
mass.

➢ Provision must be made for attachment and stowage of landing gear units.

➢ Lateral positioning (track) dictated by need to prevent overturning during ground

maneuvering.
 Tricycle Gear Configuration – Number of Wheels
As the aircraft mass increases, operations from runways of given strength dictate need
for more wheels to spread the load – many possible variants:

➢ Two-axle bogie
➢ Three-axle bogie
➢ Three or four main legs
➢ Multiple legs on single axes
Two-Axle Bogie

• The main legs are split

into two-axle bogies, with
usually two wheels per
axle.

• Such as arrangement is
generally necessary if the
aircraft mass is between
about 90 and 200 tones.

• It is common to many
civil and military transport
aircraft types.
 Landing Gear Layout
Three-Axle Bogie

For very large aircraft (e.g. > 210 tones), the load has to be spread even further – one
option is to use a 3-axle bogie arrangement.

On the Boeing 777, the extra axle is put in the

centre of the bogie.

On the C-5 the extra axle is put sideby-side with

the rear axle – the aircraft has 28 wheels in
total! Both have main bogie steering to reduce
turn radius & tyre scrubbing.
 Landing Gear Layout
Three Main Legs

Some large aircraft use an additional main leg to spread the load, e.g. Airbus A-340: 2-
wheel nose gear and 3 main gear, each of double-wheel 2- bogie – 14 wheels in total.
 Four Main Legs
➢ This will generally be the
case for very large transports
(> 300 tones) with low wing
(e.g. Boeing 747).

➢ It poses significant problems

for airframe attachment &
stowage.

Boeing 747 is a long-range wide-body airline

Four Main Legs – Boeing 747
 Landing Gear Layout
Multiple Main Legs with Single Axles
Good option for heavy high wing military transports with retraction into fuselage blisters.

The Antonov An-124 Condor has 24 wheels:

two side-by-side, 2-wheel nose legs, and ten
main legs (5 each side), each with 2 wheels.
Tail Wheel Configuration:

➢ Here the two main wheels are located forward of the CG and a tail wheel or skid
provides the third support point.

➢ This is a simpler, lighter and cheaper design than a tricycle layout but has significant

Disadvantages: Difficult ground maneuvering and take-off/landing due to inhibited

visibility.

This was the norm for many early aircraft but its application is nowadays limited to
simple light aircraft where emphasis is on simplicity and low cost – often with fixed
(rather than retractable) legs.
 Landing Gear Layout

Bicycle Configuration
This is a specialized form of the single main leg configuration but with the rear leg
significantly further back.

This results in the nose leg carrying a similar proportion of the mass as the rear leg.

Advantage is an uncluttered wing and long length of available fuselage space (e.g. for
a bomb bay).

Disadvantages are:

➢ Highly loaded nose leg makes ground maneuvering very difficult.

➢ Specialized landing technique needed, especially if in cross-winds.

 • Outriggers needed for ground roll stability.
Disadvantages
• The configuration is not recommended unless
there is no viable alternative.

Boeing B47E Stratojet

B-52 Stratofortress
 Unconventional Configurations
Biplane

➢ The norm for the first 30 years of aviation.

➢ Early airfoils were very thin requiring external bracing so that biplanes gave best
structural efficiency.

➢ Many penalties of use, especially at higher speeds – increased total mass, drag and
aerodynamic interference.

➢ Aerodynamics and materials advances have led to increased wing loadings (W/S) so
that biplanes are mostly redundant nowadays – main exception is aerobatics aircraft
where low W/S is an advantage and specialized aircraft such as crop-sprayers.
 Biplane Unequal span Biplane Sesquiplane Inverted Sesquiplane

Forward stagger Biplane Backward stagger Biplane Triplane Quadruplane

Multiplane aircraft
 Unconventional Configurations

Variable Sweep (Swing-Wing)

Design Problem:

➢ High sweep usually needed for transonic/supersonic speed designs but this affects low
speed performance.

➢ Possible solution is to use variable sweep wings.

➢ This gives a better matched performance over a wide speed range and offers an
aircraft multi-role capabilities over subsonic and supersonic speed ranges.
 Unconventional Configurations

Variable Sweep - Disadvantages

➢ Increased mass over conventional design due to heavy actuation system.

➢ Increased system complexity and costs.

➢ Increased drag due to interaction between fixed and moving parts of the wing.

➢ Trim and stability/control problems due to movements of aerodynamic centre and

CG
 Unconventional Configurations
Variable Sweep Aircraft

F-14 Tomcat
 Unconventional Configurations
Canard Layout
The conventional aft horizontal tailplane is replaced by a foreplane (or canard) while the
main wing is then moved rearwards for stability purposes.
Or
Canard are small forward wing (the canard) is placed ahead of the main wing of an
aircraft—offers several advantages and disadvantages. These vary depending on whether
the canard is designed primarily for lift or control.

Two main categories:

➢ Lifting canard – canard provides substantial lift as well as longitudinal trim and
control.
Examples: Dassault Rafale, Eurofighter Typhoon, Saab Gripen

➢ Control canard - longitudinal trim and control only.

Examples: Concorde, Rockwell B-1 Lancer, Grumman X-29, Saab 37 Viggen.

Canard Layout – Configuration Advantages

Improved Stall Characteristics:

The canard often stalls before the main wing, causing the aircraft's nose to drop gently
rather than leading to a full stall. This makes canard-equipped aircraft more resistant to
deep stalls, enhancing safety.

Better Pitch Control:

Canards can offer improved pitch control, especially in high-performance or highly
maneuverable aircraft. This is because the control surfaces at the front provide quicker
response for pitch adjustments.

No Tail Downforce:

Conventional aircraft with rear tailplanes require a downward force from the tail to
maintain balance, which slightly increases overall drag. In contrast, a lifting canard
balances the aircraft without needing such downforce, which can be more aerodynamically
efficient.
Canard Layout – Configuration Disadvantages

Lift Interference:
In certain conditions, the airflow from the canard can interfere with the airflow over the
main wing, reducing its effectiveness, especially at high angles of attack. This can limit the
overall lift or cause stability issues in some flight regimes.

Reduced Payload Capacity:

The need to position the center of gravity more forward in a canard design can limit the
payload distribution and volume. This might restrict internal space or limit the aircraft's
ability to carry heavy loads in certain areas.

More Complex Design Requirements:

Canard aircraft require careful design to ensure proper balance and stability. Achieving an
optimal weight distribution and handling characteristics is often more complex than in
conventional aircraft, leading to more intricate design and testing.
Dassault Rafale
Saab Gripen
Long-Coupled Canard Layout

• Small canard located far enough

forward from main wing so that
interference effects are small.

• Particularly suited to long-range

supersonic aircraft designs
(bombers, transports, etc.).
Short-Coupled Canard Layout

• Foreplane placed just ahead of (&

usually above) wing.
• Careful location enables lift
effectiveness.

• Most applicable to high agility combat

aircraft designs.
 Unconventional Configurations

Blended Wing Body (BWB)

It is an innovative aircraft design that merges the wings and fuselage into a seamless,
integrated shape. Unlike conventional aircraft with distinct cylindrical fuselages and
attached wings, the BWB design is more like a flattened, airfoil-shaped body where the
entire aircraft structure contributes to lift.

Example for BWB- NASA X-48, Airbus MAVERIC, Experimental BWB prototype.

Advantages of Blended Wing Body Design:

Improved Aerodynamic Efficiency:

The BWB design reduces drag because the smooth, integrated shape allows for better
airflow over the entire aircraft. This reduction in drag can improve fuel efficiency, making
the aircraft more economical to operate.
Higher Lift-to-Drag Ratio:
•Since the entire body of the aircraft generates lift, not just the wings, the BWB has a higher
lift-to-drag ratio. This results in better fuel efficiency and range compared to traditional
designs.

Lower Fuel Consumption:

•Thanks to the improved aerodynamics, BWBs use less fuel for the same distance and
payload compared to conventional tube-and-wing designs, making them more
environmentally friendly.

Greater Payload Capacity:

•The wide, spacious interior of a BWB allows for more cargo or passenger space than a
traditional fuselage, enabling more efficient use of the aircraft’s volume.

Quieter Aircraft:
•BWBs can place engines on top of the aircraft, shielding them from the ground, which can
reduce noise pollution around airports. The blended design also allows for smoother airflow
around the engines, further decreasing noise.
Disadvantages of Blended Wing Body Design:

Passenger Comfort and Layout Challenges:

1. One of the biggest challenges for commercial BWB aircraft is ensuring passenger
comfort. In a wide-body BWB, passengers seated far from the centerline could
experience more turbulence and feel motion differently, leading to discomfort.
2. Designing an efficient layout for seating, aisles, and emergency exits is more complex
than in traditional tube-shaped fuselages.

Control and Stability Issues:

•The BWB's unusual shape creates different aerodynamic challenges. Ensuring stability,
particularly in yaw (side-to-side movement), requires advanced control systems and design
solutions, which add complexity to the aircraft.

Certification and Regulatory Hurdles:

•The unconventional design of the BWB may face challenges in meeting existing aviation
safety and certification standards, which are based on traditional aircraft configurations. This
could slow down the approval process for new BWB designs.
Ground Handling and Airport Compatibility:

•The BWB's wide, unique shape might require modifications to existing airport
infrastructure, such as terminals, jet bridges, and taxiways, to accommodate these
aircraft. This would involve significant investment and changes to airports.
Boeing X-48
 Unconventional Configurations

V/STOL Airlifters – Tilt-Wing

A tiltrotor aircraft is a type of aircraft that combines the vertical takeoff, hovering, and
landing capabilities of a helicopter with the high-speed, long-range flight performance of a
fixed-wing airplane.

How Tiltrotor Aircraft Work:

Vertical Takeoff and Landing (VTOL) Mode:
•In this mode, the rotors are in the vertical position, much like helicopter blades. The aircraft can take off
and land vertically, hover, and perform low-speed maneuvers. The rotors generate lift in the same way as a
helicopter’s rotors, making it ideal for operations in confined spaces or areas without runways.

Transition Mode:
•After takeoff, the nacelles (which house the rotors) tilt forward gradually, transitioning the rotors from a
vertical orientation to a horizontal one. During this transition, the lift gradually shifts from the rotors acting
as helicopter blades to the wings generating lift like an airplane.
Airplane Mode:
•Once the nacelles and rotors are fully tilted forward, the aircraft operates like a fixed-wing airplane. The
wings now provide most of the lift, and the rotors act as propellers to generate forward thrust. This allows
for much faster speeds and greater range than traditional helicopters can achieve.

Advantages of Tiltrotor Aircraft:

➢ Vertical Takeoff and Landing

➢ High Speed and Range
➢ Versatility

Disadvantages of Tiltrotor Aircraft:

➢ Mechanical Complexity.
➢ Cost as compared with conventional helicopters
➢ Heavier Weight: mechanisms needed for tilting
➢ Noise and Vibrations
STOVL (Short Take-Off and Vertical Landing) – Thrust Vecoring

A thrust vectoring use advanced technologies to direct the exhaust of their engines to
control the aircraft’s movement and allow for vertical or short-distance takeoffs and
landings.

Thrust vectoring allows the aircraft to manipulate the direction of the engine's thrust for
greater agility and maneuverability, especially in low-speed and hover flight modes.

Examples: Lockheed Martin F-35B Lightning II, AV-8B Harrier II / Sea Harrier:
 Advantages Disadvantages

Enhanced maneuverability in combat Increased mechanical and operational complexity

STOVL capabilities (e.g., for F-35B, Harrier) Higher maintenance and operational costs
Stealth integration (reducing control surfaces) Higher fuel consumption in non-optimal flight

Better control during low-speed flight or hover Increased pilot workload

Improved control at high angles of attack Added weight to the aircraft

Lockheed Martin F-35B Lightning II
 Unconventional Configurations
Stealth
Increasingly important for modern combat aircraft designs.

Final configuration depends heavily on overall priority of stealth against performance.

Stealth – Key characteristics

➢ Internal powerplants & weapons.

➢ Intakes with long curved ducts.
➢ Exhausts must be shielded.
➢ Avoid surfaces positioned at right angles to each other (e.g. use inclined fins).
➢ Minimize discontinuities in shape/surface.
➢ Surface edges parallel to each other.
Waterborne Aircraft

➢ Very common in the early days of aviation.

➢ Can operate from anywhere with a large stretch of reasonably calm water.

➢ Use nowadays restricted to small aircraft operating in coastal regions or in remote

locations with many lakes & rivers.

➢ Two basic categories – float planes & flying boats

• Waterborne Aircraft – Float
Planes

• Conventional landing gear

replaced by large floats.

• Invariably propeller-driven.

• Usually only applicable to

small aircraft (12 tones max).

• Air drag of floats are high

Waterborne Aircraft – Flying Boats

➢ Usually larger than float planes.

➢ Fuselage used as a hull for waterborne

operations.

➢ Wing tip floats or fuselage sponsons used to

provide waterborne roll stability.

➢ Some types also have conventional

retractable landing gear and are then
amphibious.
 Development in Propulsion over
the years:
Power or Propulsion is the supplied energy given to the
aerodynamic body for the generation of lift and drag.
The past memories of aviation said, George
Cayley designed his air-plane with Paddles in 1799.

Henson and Stringfellow used steam

engines as the power source for the “Air-
screws”.
Felix Du Temple in 1874, and Mozhaiski in 1884 strongly
referred Hot-Air Engine such as steam engine. By the late
19th century, the early aeronautical engineers clearly
recognized that, a successful flight is depended on the
light weight and powerful engine.
Langley and the Wright Brothers designed their own
gasoline powered engines in order to obtain the high
horse power to weight ratio necessary for flight. These
Internal combustion reciprocating engines were used to
drive the propeller up to the world war-2.

An inline, four cylinder water-cooled engine, its crankcase

was made of aluminum to reduce weight, the first time an
aircraft engine had an aluminum component. Today, the
majority of aircraft engines are made of aluminum. In operation,
the engine could push 12 horsepower.

They designed the powerful engines of 12 hp to 2200

hp Radial engines with the velocities of 12.5 to 224
m/sec in the years between 1903 to 1945.
The 1st jet propelled engine was patented in 1930 by
a Britain man Frank Whittle. The 1st successful
German Heinkel He 178 air-plane flew with a
turbojet engine in 1939 designed by Dr. Hans
VohDhain. This led to the German Me 262 jet fighter
late in world war -2. The jet engine’s flight velocity
was improved up to speed of sound in 1950s and
beyond in the 1960s and 1970s.
 Evolution of Aircraft Material
The development of materials and structures in aircraft design has been a crucial area of
research and innovation, driven by the need for lightweight, durable, and high-strength
components that can withstand various operational stresses.

Here’s an overview of how materials and structural designs have evolved in aircraft over
time:

1. Early Materials and Structures (1900s - 1940s)

➢ Wood and Fabric Construction: The earliest aircraft, including the Wright brothers' flyer,
were made primarily of wood (such as spruce) and fabric. Wood was strong for its
weight, easy to shape, and provided the structural flexibility needed for early designs.
Fabric was used as a covering material due to its light weight.

➢ Steel Tubing and Wire Bracing: As aircraft technology advanced, lightweight metal tubes
(often steel) started to replace wood for internal frames and bracing, which allowed for
greater strength and durability. Wire bracing provided additional strength and structural
stability.
 Wood,
Fabric, and
Twine
2. The Introduction of Metals (1940s - 1960s)

•Aluminum Alloys: Aluminum became the dominant material

in aircraft structures during World War II due to its high
strength-to-weight ratio, resistance to corrosion, and ease of
fabrication. This transition allowed for stronger, lighter
aircraft capable of higher speeds and longer ranges.
•Monocoque and Semi-monocoque Designs: Structural
design shifted from truss-based systems to monocoque and
semi-monocoque designs, where the skin of the aircraft took
on more of the load. This design reduced the weight by
integrating the aircraft's skin as a load-bearing structure.
•Magnesium and Titanium: Magnesium alloys, although
prone to corrosion, were sometimes used due to their low
density. Titanium also began to emerge for certain applications
requiring high strength and temperature resistance, such as jet
engines and some structural parts, especially in military
aircraft.
3. Composite Materials and Advanced Alloys (1970s - 2000s)

•Carbon Fiber and Kevlar: In the 1970s, carbon fiber composites were introduced in
military and later commercial aircraft due to their very high strength-to-weight ratio and
corrosion resistance. Kevlar was used as a lightweight alternative, particularly in areas
requiring impact resistance.

•Advanced Aluminum Alloys: Advanced aluminum alloys, such as aluminum-lithium,

reduced weight and provided greater fatigue resistance, allowing aircraft to endure repeated
stress over long periods.

•Titanium Use in High-Temperature Zones: Titanium use expanded for high-temperature

areas in commercial aircraft, particularly in and around jet engines and in fasteners.
4. Modern Aircraft and Advanced Composites (2000s - Present)

•Widespread Use of Carbon Fiber Reinforced Polymer (CFRP): Modern aircraft like the
Boeing 787 and Airbus A350 use around 50% or more composite materials, primarily carbon
fiber-reinforced polymers (CFRP). CFRP materials are strong, lightweight, and resistant to
corrosion, allowing for complex aerodynamic shapes and fuel-efficient designs.

•3D-Printed Metals and Composites: Additive manufacturing, or 3D printing, is now being

used to produce complex shapes in metal and composite materials that would be difficult or
impossible with traditional manufacturing methods.

•Smart Materials and Structures: Emerging materials, such as shape memory alloys and
morphing structures, can adapt to environmental conditions or adjust their properties in real
time. This may lead to wings or control surfaces that can change shape for optimal aerodynamic
performance.
5. Future Trends and Innovations

•Hybrid Structures and Multimaterial Composites: The future may see hybrid
structures that combine metals, composites, and other advanced materials for optimal
performance. New alloy and composite combinations aim to maximize strength,
flexibility, and corrosion resistance while minimizing weight.

•Nanotechnology and Self-Healing Materials: Nanomaterials, such as carbon

nanotubes, are being explored for their potential to increase strength, reduce weight, and
improve electrical conductivity.

•Self-healing materials could allow small cracks or damage to repair autonomously,

potentially enhancing safety and longevity.
Today, manufacturers are developing advanced composites to build the aircraft of the future.
Main parts of helicopter