The document discusses several key advancements in aeronautical engineering history. It describes the early pioneers of flight including George Cayley who invented the concept of the modern airplane and introduced ideas like fixed wings and horizontal and vertical stabilizers. It also discusses Otto Lilienthal and Octave Chanute who continued experimenting with gliders. However, the most significant advancement discussed was the invention of the jet engine, which revolutionized aeronautics by enabling vastly higher speeds and altitudes compared to piston engines. The jet engine required redesigning all aspects of airplanes to withstand the new pressures and temperatures. It also drove the development of new high-performance materials.

1. Which Aeronautical advancement was the most
significant?
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2. Contents
FOREWORD..................................................................................................................................3
INTRODUCTION............................................................................................................................ 4
THE AGE OF GLIDERS .................................................................................................................... 5
The Works of Sir George Cayley 1773-1857 ................................................................................ 5
Otto Lilienthal-The Glider Man (1848-1896) ............................................................................... 6
Aeronautics came to the USA- Octave Chanute 1832-1910.......................................................... 7
Summary..................................................................................................................................8
THE JET ENGINE REVOLUTION .......................................................................................................9
Engine Propulsion..................................................................................................................... 9
Problems................................................................................................................................ 10
Improvements and New Problems........................................................................................... 11
Performance........................................................................................................................... 12
Summary................................................................................................................................ 14
MATERIALS................................................................................................................................. 15
Before the Jet Engine.............................................................................................................. 15
After the Jet Engine................................................................................................................. 16
High Temperature Materials.................................................................................................... 16
High Pressure Materials .......................................................................................................... 17
High Tensile Strength Materials............................................................................................... 17
Summary................................................................................................................................ 18
CONCLUSION.............................................................................................................................. 19
BIBLIOGRAPHY........................................................................................................................... 20
Internet sources ..................................................................................................................... 20
Books and Journals....................................................................... Error! Bookmark not defined.
Audio-visuals.......................................................................................................................... 21

3. FOREWORD
Aeronautics, as I define it, means to movein the air, with Aero meaning ‘air’ and nautic
meaning ‘to move' or 'to navigate’. To be an aeronautical engineer is to be able to effectively
design and mentor the manufacturing of machines whichmove in the air; such as an aeroplane.
However,does that mean building and flying a kite makes youan aeronautical engineer? Well
no, to be an accomplished engineer, the machines and systems youbuild must be for the
forwarding of mankind and life on Earth.
Aeronautics is something whichhas interested me formany years. My interest in this subject
blossomed during a family holiday in 2011, sitting by the window seat in a Boeing 787; I
observed how the wing shape changes during the various stages of flight. When I saw the flaps
of the wing extend down, increasing the wing area during takeoff,and the flaps comeup during
landing, I was fascinated to say the least. This Extended ProjectQualification(EPQ) allowedme
to explore my interest in aerodynamics, and other aspects of aeronautical engineering too. I
have come to admire the complexity and creativity of engineering and respect how aeronautics
benefits mankind.
The purpose of this EPQis topresent to youthe journey of my first glimpse into the subject I
wish to study at University and hold as my profession. Visiting libraries to access different types
of books and accessing information on the internet, introduced me to the basics of aeronautical
engineering. My EPQalso touches upon the historical aspect of aeronautics because of my own
separate passion forhistory, whichI believe is naturally intertwined with a passion for science.
It is very interesting to see how our technology and understanding of the forces and
mechanisms around us have advanced and strengthened through the years.
I decided tochoose the question 'Whichtechnicaladvancement in the history of Aeronautical
Engineering was the most significant and beneficial?' as my guide. I thought it was a question
whichwould involveless reading and copying frombooks, and more thought and evaluation.
I hope you enjoy this brief project.

4. INTRODUCTION
Flying has alwaysbeen seen as a miraculous spectacle. Eventoday, scientists still actually
ponder how a change in pressure across the wings, or some theoretical application of Newton’s
laws, allows something to become airborne. It was this principle of flight, founded by the fathers
of aeronautics, whichallowed the skies to become our highways. From the onset of the
pioneering age, key figures such as George Cayley,Otto Lilienthal and the Wright Brothers
edged us closer and closer to finally fulfilling the dream etched into the minds of mankind,
sustainable flight.
The need to advance and ease human travel is what shapes the designs of our aeroplanes today
and it is whatdrives our engineers to improve this exciting method of transportation. For
example, cargo planes should be made to have larger wings, a passenger plane should be built to
be more fuel efficient,and a fighter jet's structure should be designed to be more agile and to
travel further on the same fuel. This essay is centred around the various improvements in
aeronautical history from the very first powered flight, whichopened up the doorway to the
pioneering age of discovery and luxury, to the most significant advancement of them all, the jet
engine, which separated the old fromthe new and the archaic fromthe modern.
The jet engine, coulddeliver so much thrust it required a rethink and redesign of every aspect of
the aeroplane. The aerodynamics of the aeroplane had to survivethe higher speeds and
altitudes whichcould not be achieved withan internal combustion engine. New materials were
needed to cope with the pressure changes and drop in temperature whichcame with flyingat
the altitudes whichhad not been reached before, but materials also needed to cope with the
higher temperatures of the powerfuljet engines. It was this new powerful method of propulsion
whichbegan the exponential growth of aeronautical technology and allowed our global travel
market to be what it is today.

5. THE AGE OF GLIDERS
From the dawn of human intelligence, the idea of flyingwas etched into the minds of all those
yearning to take the sky and join the birds in their flight. The first attempts in taking the sky was
a very primitive one; simple bird imitations would forsome centuries be the ideal method of
conquering the sky and of course would alwaysend in failure. However,it is wrong to think that
imitating birds is an absolute waste of time and effort when in factmuch of our highly advanced
aeroplanes today use mechanisms which evolvearound the imitation of birds.
By the end of the 18th century, one man would change the conceptof flight and aeronautics
forever. Inspired by Leonardo Da Vinci, George Cayley would cometo change the pathway of
aeronautics by inventing the modern airplane in 1799. Cayley’s experiments and designs would
come to inspire a chain of ambitious aeronautical engineers and flight enthusiasts, such as Otto
Lilienthal and OctaveChanute. Through their individual works they paved the way for one of
mankind's greatest achievements of the 20th century;powered and controlled flight.
The Works of Sir George Cayley 1773-1857
Cayley completely abandoned the conceptof “wingflapping” as his basis of flight; imitating
birds had been the main concept for centuries. Instead, Cayley envisaged that flight would only
be successful by separating liftand propulsion completely.He introduced horizontal and
vertical stabilizers in the tail forflight stability and came up with the concept of fixed wings.
Cayley was also the first to state that lift was generated by low pressure on the upper surface of
the wing. By this Cayley opened the door to modern aeronautical science and earned his title as
the "Father of aviation". 18
Fig 1.0 Cayley's invention of the first modern aeroplane in 1799 Source: Introduction to flight p1-35 (18)
Sir George Cayley's first design of the glider was also the first design of the modern aeroplane,
whichwould inspire generations that later culminated into the Wright Brothers success. Figure
1 shows the first model designed, built and flownby 1804; it was the first to have a fixed wing
and also had an adjustable tail.
Howeverthe aeroplane was too young of a technology and flight using balloons (First achieved
by Montgolfier in 1783)25 was much more experienced and suitable to the premature industry
of the time.
George Cayley maintained his efforts to produce an airplane, and in 1849, he built and tested the
first full size aeroplane, the infamous BoyCarrier.

6. Fig 1.1 George Cayley's Boy Carrier, Source: Introduction to flight p1-35 (18)
The “boy carrier "was a triplane; Cayley was the first to suggest this sort of idea of wings fixed
on top of each other mainly as a caution in case one wing broke. This concept perpetuated into
the early 20th century and laid the foundation of aerostructures, such as bi-planes, in the late
19th and early 20th century.
This aircraft was made with:
 A fixed wing at an angle of incidence for lift
 An adjustable tail for horizontal and vertical stability
 A pilot operated elevator and rudder
 A fuselage in the form of a car
What was special about this model is the factthat it contained a pilot operated elevator and
rudder, the first of its kind and a technology which is still being used today.Nonetheless, flight
was still very immature in the mind 19th century and Cayley was forced to revert backto using
flappers forpropulsion, simply due to one glaring problem; a suitable engine was simply too
heavy for effectivelift.This problem, which encased the mind of every aeronautical engineer,
was finally solved in 1903 by the Wright Brothers.
Otto Lilienthal-The Glider Man (1848-1896)
Otto Lilienthal was the first human to sustainably fly before the invention of powered and
controlled flight in 1903, whichrespectfully earned him the title of 'GliderMan'.In1891, Otto
Lilienthal literally jumped into the air with his monoplane glider and flew in a fairly controlled
fashion.
Lilienthal was very much influenced by the works of Leonardo Da Vinci and George Cayley,
howeverhis methods of research and investigating were unique compared to other early
aeronautical engineers. He focusedvery precisely on the anatomy of bird wings as the basis of
the structure of his monoplane glider and combined that with the fixed wing idea proposed by
Cayley. In 1889 Lilienthal published a book titled “Birdflight as thebasis of aviation” 18.
Lilienthal wouldalso come to have a philosophical impact on aeronautics forthe next couple of
years since he believed that the best way to study flight was by getting up into the air and
experimenting yourself.

7. “One can get a proper insight into the practice of flying only by actual flying experiments…The manner in which
we have to meet the irregularities of the wind, when soaring in the air, can only be learnt by being in the air
itself…”
Fig 1.3 Otto Lilienthal's Philosophy on aeronautical research, Source: Introduction to flight p1-35 (18).
Lilienthal tookhis own adviceand in 1894 and made the first successful non-powered flight
with his monoplane hang-glider.
Fig 1.4 Lilienthal’s flight attracted large audiences, Source: secret of
flight (8)
Lilienthal’s No.11 glider was the most reliable
one he built, made from willow branches and
English shirting material, this devicemade its
first flight in 1894, flying hundreds of metres.
Lilienthal made over2000 flights with his gliders and his inventions became imperative to the
future of flight. The main conceptlearnt from Lilienthal was that flight could be maintained
without putting in any effort,contrasting previous ideas of looking at flight in a brute force
manner. Lilienthal's workwas quintessential to understanding flight stability.
Aeronautics comes to the USA- Octave Chanute 1832-1910
For the decades between the 1850's and 1890's, Britain and Europe where at the centre of the
early aeronautical advancements. In contrast, throughout this time the United States was busy
consolidating its new government and expanding its frontiers. There was not much interest in
aeronautics at the time however,in 1875, a French-born US citizen named OctaveChanute
intensively researched the worksof previous pioneers' work on aeronautics and aviation, and
built his famous Biplane Hand Glider in 1896.
Of all the gliders built by Chanute, this Biplane was the most successful. Its outstanding feature
was the use of verticalstruts and wire
cross-bracing to make the wing structure,
whichwas the same cross bracing method
used in railway bridges at the time.
Weighing only 14kg, this system combined
strength and lightness so effectively thatit
was to become the standard forbiplanes
ever since and be the standard structure
for the Wright Brothers' airplane. Most
importantly the biplane was so safe that
Chanute allowed journalists to fly it.
Fig 1.5 Chanute's biplane hand glider, , Source: Smithsonian National Air and Space Museum (9)

8. Summary
The advancements of pioneers of the late 19th century were small, but precious. Sir George
Cayley opened the door to modern aeronautics with his design of the fixed wing aeroplane. Otto
Lilienthal's wing design, inspired by birds, would also lay the foundations of monoplane wing
design. Finally,OctaveChanute's cross-bracing wouldbe the basis of wing design for biplanes; a
short-lived but a substantial era of aeronautics where aeroplanes wouldplay a greater role.
Gliders broke us away from the idea of flapping like birds to fly and brought closer to controlled
and sustained flight. With the revolutionary flight in Kill Devil Hills in 1903, the beginning of the
20th century was full of an adventurous zeal forflying; the world witnessed the first insight into
a method of transportation whichwouldrevolutionize our travel, global connectivity and
warfare.
However,the advancements which these pioneers contributed to aeronautics were not the most
significant. Although their designs lay vital foundations of understanding, new challenges
emerged such as making flight safe, increasing flight ranges so that flight can be commercialized
and making flight more sustainable. Their works unfortunately did not perpetuate through the
decades, but planted the seed forfixed wing aircraft. New evolutionary advancements in
aerostructures replaced their designs.

9. THE JET ENGINE REVOLUTION
In the year 1903, the Wright brothers revolutionized aeronautics with the first engine
propelled flight. Aeroplanes could fly further, faster and higher. Likewise, in the mid 1940's
another propulsion revolutionoccurred withthe invention of the first practical jet engine,
whichmade high-speed flight possible with aeroplanes reaching speeds, altitudes and flight
distances that could not be achieved using piston engines. Jet engines also opened the world to
safe, reliable and efficienttravel. However,this revolution of propulsion would come to induce
another much needed upgrading of the material industry, since with greater altitude and speed
comes a much greater performance requirement from the aircraft materials. Also, the
aerodynamics of aeroplanes had to be adapted to cope with these new speeds.
This remaining chapter begins by firstly discussing the differencein engine performance
between the early piston engines and the jet engine. As engine performance came to be at the
centre of aircraftmodernization and overall enhancement, this is followedby how the jet engine
has affectedaerodynamics and material performance.
Engine Propulsion
Propulsion before the invention of the jet engine was mainly produced frominternal
combustion engines and propellers.
Propellers use aerodynamic forceto generate thrust; a method widely used in the internal
combustion era due to inefficient engine performance. The illustration shows that these
propellers have a cross section similar to aerofoil sections, howeverunlike wings; the aerofoils
are not in the same direction. The propeller is twisted so that at the root nearest to the hub, the
chord line is parallel to the relative wind, while at the tip it is almost perpendicular. The shear
stress and pressure distribution overthe propeller blade creates an aerodynamic force;
howeverthese forces actin different directions (vectors) due to the twisted blade. These two
forcesare lift and drag, where the resultant is the net thrust.
Fig 3.0 Diagram of a standard propeller, Source: Introduction to flight p475-449 (18)
The basic operation of internal combustion engines is a piston moving back and forth, which
powers a machine with a typical fourstroke cycleas illustrated below18:
a) INTAKE STROKE: the intake valveis opened and the piston moves
down and the gasoline enters the cylinder.As the volume is increased,
its pressure stays the same since the valveis open.

10. b) COMPRESSIONSTROKE:The intake valvecloses and the piston
compresses the gasoline liquid, increasing the pressure of the cylinder.
At the end of this, the mixture is ignited usually by an electric spark,
drastically increasing the pressure while the volumeis constant. The
energy let off by the ignition leads to the next stroke.
c)POWERSTROKE:The energy of the gasoline ignition forcesthe
piston downwards,releasing the pressure and turning the crankshaft
whichdrives the propeller to produce thrust.
d) EXHAUSTSTROKE:As the piston is forceddown, the pressure
decreases. Then the exhaust valveopens and the ignited gasoline is
forcedout by the piston in another stroke. The pressure of the
cylinder is returned to how it was during the intake stroke, and the
cyclebegins again.
Fig 3.1 Series of diagrams on the sequence of piston engine strokes Source: Introduction to flight p449-479 (18).
Problems
The main problem with both the propeller and the combustion engine was the efficiency of
their poweroutput. The piston engine is on average 15% efficient.Energy is lost in many ways,
mainly through frictionin the components and heat transfer. Itis this low efficiency which
means piston engine aircraft could fly no faster than 300 km/h. In addition to the hindrance in
speed, these factors affectthe engines power output, which directly affectsthe power output of
propellers. Maintenance of Piston engine aircraftwas also more intensive than Jetengines, with
Piston engines requiring maintenance approximately every 2000 hours, due to more moving
parts13.
Jet engines were being developed in the mid 1940's by both British and German engineers
during the Second WorldWar, with both countries vyingto be the supremacy of the skies. The
invention of the Jet engine by Frank Whittle and Hans van Ohain was an example of how war
can be a driving stimulus forscientific and technological breakthroughs. Nonetheless, the Jet
engine was revolutionary due to its impact on the worldof aircraft, military and civil.
The way the Jet engine produces thrust is an example of Newton'sthird law. However,another
way the jet engine produces thrust is similar to how propellers produce thrust. The result of the
high pressure in the engine forcesthe hot air out similar to the pressure described previously in
the cylinder of a piston engine. The followingparagraphs look at the Newtonian aspect of thrust
generation of jet engines, using Turbofanengines as the example since the power the majority
of planes today.
Turbofans worksimilarly to Turbo Jets; air is sucked in, pressurized and rapidly depressurises
when it is blasted out through the nozzle at a much greater velocity than when it entered. The
forceof the exhausted air against still air particles is whatthrusts the aircraft forward,hence
Newton'sthird law; howeverwith Turbofans the engine is fitted with a powerfulfront-end fan,

11. whichsucks in more air and creates a secondstreamtocool downthe engine. The followingis
the sequence of how turbofans produce thrust;
1. The large fan, which is a large diameter encased propeller at the front of the engine,
accelerates a primary airflow through the various components of a typicalturbofan engine. The
secondary airflow passes only through the fan and cools the engine; this airstream is also
exhausted in the exhaust assembly.
2. The air passes through the low and high pressure compressors, whichgradually increase the
pressure of the air. The temperature in the compressor chambers can reach as high as 450oC.
3. The pressurised air then enters the combustion chamber, jet fuel is mixed withair and
ignited; the temperature reaches up to 1700oc.
4. The accumulated energy from the increase in pressure is convertedin the stages of the
turbine chamber; the pressure of the air drops as it expands and passes through the turbines
making them spin. This concentric spinning of the turbines within one another operate the fan
and the compressor fans. The Turbofan is therefore a flow cycleengine, since the turbines
operate the fan and compressors.
5. Finally, the hot air is forcedout of the exhaust assembly, which is narrowed to maximize the
speed of the exhausted air, generating more thrust.
Source:CFM International26
Fig 3.2 Diagram of
a turbofan engine
Source:
Introduction to
flight (18).
Improvements and New Problems
Due to the jet engine having fewerparts the flight hours before maintenance is approximately
3000 hours, which is much longer than the older internal combustion engines. So, although jet
engines are more expensive to build, their maintenance costs are much lower. They are also
lighter compared to a piston engine whichproduces the same thrust12. The jet engine has made
flight much more affordableand sustainable, whichgreatly expanded the air travel sector and
allowed businesses to invest more in global air travel. Jet engines are also far more efficient.
Efficiency isgreater when the velocity of the exhausted air is closer tothe velocity of the
aircraft, whichis why jet aircraft flyingat greater altitudes are more efficient. At a greater
altitude, the atmosphere is thinner, so there is less drag. ;This means that less energy is required
for an aircraft flyingat a higher altitude than an aircraft flyingat the same speed, but a lower
altitude, or, the same amount of energy will see an aircraft at higher altitude fly faster that an
aircraft at a lower altitude.

12. More precisely;
Where c is the exhaustspeed,visthe aircraftvelocityandηp is the efficiency.
(Source:http://en.wikipedia.org/wiki/Propulsive_efficiency)13
.
More specifically:
Fig 3.3 Graph highlighting how an increase in Mach number of aircraft increases efficiency of engine. Source: Propulsive efficiency ( 13).
The Mach number is defined as the ratio of the speed of the objectto the speed of sound. Bypass
ratio is the ratio of the air sucked in by the fan into the secondstreamtothat used in the
combustion sequence. Therefore, as the speed/mach number increases, the efficiency of the
engine increases.
Performance
Beforethe jet engine there was still a great deal of research being conductedin finding the
most effectiveaerofoil to increase the area of laminar flow and even today there is a great deal
of research and experimentation being conductedto achieve as close to 100% laminar flow on
wings as possible. The maximum speed of aircraft steadily increased during the age of
propellers and piston engines; the maximum speed achieved in 1920 was 125 mph to nearly
450 mph during WW2. The highest maximum speed shown is forthe P-51Daircraft whichhad a
speed of 437 miles per hour at 25,000 feet. Late in the war,a Republic P-47J achieved a speed in
level flight of 507 miles per hour at 34,000 feet. The maximum speed is reliant on the engine
power, whichalso steadily increased in the pre-jet era16.

13. Before the jet engine was invented progress in creating more powerful engines was relatively
slow. Therefore, a great deal of research went into designing new aerofoils and aero structures
whichwould reduce drag so that higher speeds were achieved with the same engine. .
However,with the design of the jet engine and with more thrust being generated, there was an
urgent need to refine the wing design and body structure of aircraft to minimise the drag
created by the fast moving wind. A new design was needed forthe structure to survive these
speeds and enhance performance.
Today a common design used for aeroplanes to endure these new speeds is with swept and
delta wings.
Nearly all modern high speed aircraft have swept and delta wings, but why?The benefit lies in
how this design allowsthe aircraftto reach greater speeds. When the wings are swept back,
only a component of the oncoming airflow would contribute to the induced drag. There is an
alternate explanation to why a swept wing increases the maximum speed; a swept wing will
decrease the thickness ratio of the wing thus reducing drag and allowing the Mach number to
increase.
Fig 3.5 The French Dassault-Breguet Mirage 2000c is an excellent example of
effective delta wings, Source: Introduction to flight p182-226 (18)
Fig2.6 Vectors involved in swept wing design Source: Introduction to flight
p182-226 (18)
After the invention of the jet engine, flaps on wings became much more common. An aeroplane
usually experiences its slowest speeds during take-off and landing. The slowest speed in which
an aircraftcan fly at level flight is called the stalling speed. Stalling speed must be as small as
possible for vitalsafety reasons, so that during take-off or landing (where stall speed is almost
reached) the pilot wouldnot lose controlof the aeroplane. Todecrease the stalling speed, the
maximum coefficientof lift must be increased. Flaps are used to "artificially"enhance the lift
properties of a wing; flaps increase the coefficientof liftas;
1. When using a flap the camber of the wing is increased; the more camber an aerofoil has at a
given angle of attack,the higher the lift coefficient.
2. When the flap is deflecteddownwards it constitutes a chord line whichcauses an increase in
the angle of attack.

14. Fig 3.7 Different designs and variations of flaps that artificially increase the coefficient of lift, Source: Introduction to flight p182-226 (18).
Summary
Beforethe Jetengine revolutiona great range of aero structures did not exist; all
advancements in aerodynamics beforeWW2 were evolutionary and were only feeding off the
slow evolutionof internal combustion engines. However,even without the introduction of the
jet engine the performance of aircraftwas enhanced with the introduction of the modern
aerofoil shape and moving away from the wing design of biplanes. The Jet engine however,had
such a significant impact on aerodynamics, (due to the higher levelof thrust produced which
allowed aircraftto reach speeds never achieved before). Higher speeds meant that the
aerodynamics of high speed aircrafthad to be redesigned. The jet engine opened a gateway to
various new wing designs and aero structures, such as swept forward/backwings, delta wings
and winglet design, cementing its significance in the advancement of aeronautical engineering.

15. MATERIALS
The De Havilland DH 106 cometwas the first jet powered commercial aircraft. However,a year
into service the aircraftsuffered catastrophic metal fatigue in the airframes with three of its
aircraft breaking up in mid-flight completely ruining this aircrafts prospects in the commercial
travel business. This is an example of how the aerospace industry of the 1950's was still
immature and was not ready to cope with fast high altitude flight made possible by jet engines.
Nonetheless, the jet engine had a drastic effecton aerospace materials.
The demand for more advanced aerospace materials was introduced with the invention of the
jet engine; the importance of structural integrity and material performance became integral to
aircraft advancements.. Although the performance of aerospace materials has changed, fromthe
very first fabrics, to the advanced alloysand composites used today,one important aspect
regarding aerospace materials has remained the same; the need touse environmentally friendly
and costeffectivematerials. As stated by the institute of physics in the introduction of their
book, “Aerospacematerials”
“It is essential that the supply chain in the industry faces the prime drivers of cost (initial and life cycle), to-to-
market and platform performance. Aerospace materials and associated design and manufacturing processes
must be optimized in an integrated manner so as to deliver product competitiveness. The demands of
increasing environmental constraints enforced by local and worldwide legislations must also be addressed.
These challenges will only be met if the platform suppliers and material and semi-product manufacturers
collaborate effectively in strong partnerships to deliver the goals of minimum cost and maximum performance
in the required time-scales.”
Fig 3.8 Source: Institute of physics: Materials science and Engineering: Aerospace materials
Important definitions for understanding material properties are;
 Specific strength: The specific strength is otherwise known as the strength-to-weight
ratio, the units are
𝜌
𝑘𝑔/𝑚3
.
 Ultimate tensile strength: UTS is the ultimate stress a material can withstand before
breaking, where stress is defined as
𝐹
𝐴
.
 Yield strength: Yield strength is the stress point at which a material begins to plastically
deform; plastic deformation being the point where a material deforms out of shape to
never return to its original form.
 Ductility:Ductility is the materials ability to stretch while under a stretching force and
return to its original form.
 Malleability: Malleability is a materials ability to perform under a compressive forceand
return to its original position.
Before the Jet Engine
The first aerospace materials used where organic and fromnaturally occurringresources.
Although primitive compared to the materials used today, the materials selected had to be of the

16. highest quality. These included such materials as timber for wing structures
with fabric and dope to cover them; the timber would carefully selected14.
With the First World War the age of pioneering was ground to a halt and the aeroplane was
quickly transformed into a war machine. With the new demand of fighter aircraft the British
National PhysicalLaboratory was responsible for"one of the first deliberately designed
aerospace material"14. This material, the Y-alloy,wasthe first of a series of high strength, high
temperature HiDuminium alloys. The name HiDuminium is derived fromhigh duty aluminium
alloys18.
Before the Jet engine advancement of material technology was used mainly in refining the
manufacturing process with new evolutionary breakthroughs. The manufacturing process and
aircraft performance was steadily made more efficientwith new composite materials and
coatings being discovered.
A great deal of research also wentinto aircraftengine materials whichbenefitted from
improvements in the car industry. The use of refractory alloyswith very high melting points
made aircraft engines much more reliable, increasing the range of flight.
After the Jet Engine
The advancement of alloys and other materials was intertwined with the advancement of
aeroplane engines. For instance, with the invention of turbine engines by Frank Whittle and Van
Ohain, there was a demand forhigh-temperature materials which wouldsurvive inside
combustion chambers and the nozzle. Similarly, with new speeds being achieved by aeroplanes
pressure resistant materials were now in high demand.
Historically, the advancements in materials technology have been evolutionary.However,with
the Jet engine revolutionunder-way, new revolutionary materials were required to maintain
the performance of jet aircraft. Composites were the fundamental basis of these new
revolutionary materials; they are materials made from a combination of elements whether it be
different metals making up an alloy or different orientations of carbon fibre or glass fibre, to
combine and improve the properties of the individual elements
Even now there is a high demand for stronger, tougher, but lighter materials as commercial
aeroplanes continue to become bigger to maintain the booming global air travel market. This is
important as wedon't want aircraft to become heavier with increased toughness, since this
would result in greater fuel consumption.
High Temperature Materials
Increasing the temperature of the atmosphere a material is in has many effects;it reduces the
strength, increases the rate of corrosion and oxidisation of materials. High temperature
materials are at the coreof material engineering. It is the science of maintaining material
properties to as high of a temperature as possible.
Carbon Composites are used extensively in modern aircraft due to their high specific strength.
The ability to withstand high temperatures without increasing in size makes it an effectivehigh
temperature material. However, carbon composites, in their natural form, are susceptible to
significant oxidisation (rusting) at temperatures above 500℃. To address this problem a layer
of Silicon raises the limit to approximately 2200℃.

17. Ceramic is another example of a good high temperature material; used extensively in the nose
caps of space shuttles to withstand soaring temperatures of atmospheric re-entry. They are also
used as coating layers for turbine blades20.
High Pressure Materials
As previously mentioned, carbon fibres have useful high temperature properties. Although
being expensive, their excellent strength-to-weight ratio makes them the ideal material for
aeroplane structures20.
fig. 3.9 Carbon fibre wings used in the A350 XWB. Source: Airbus Official Website.
High Tensile Strength Materials
Hybrid composites are materials whichare constituted with three materials, withat least one
of them being a metal. These Hybrid composites, otherwise knownas Metal Matrix Composites
(MMC) are more advanced compared to most composites.
Titanium-Aluminium Alloys are an example of MMC; they have very high tensile strength and
they can withstand oxidisation to temperatures up to 1600℃. They also have a very high
melting point making them ideal foruse in landing gear systems, as they are able to withstand
shock and impact and the high frictionaltemperature20.

18. Fig 3.91 The Landing gear of a Boeing 777-300 Source: Wikipedia: Landing gear (11).
Summary
Material advances can be linked backto how the jet engine was at the core of the
revolutionary aeroplane redesign. Materials were gradually improving before the 1940’s, with
advancements in melting points and tensile strength. But, with the catastrophe of the De
Havilland in 1954 it was made clear that new, advanced materials were required foruse on
aeroplanes. The jet engine's impact on flight required revolutionary materials designed to
handle the higher altitudes, greater changes in pressure, new extreme temperatures (hot and
cold),increased forces and stresses; it was composite materials whichwould be at the core of
modern aircraftdesign.

19. CONCLUSION
Boththe first powered flight in 1903 and the invention of the jet engine were revolutionary
advancements. However,in my opinion, the invention of the Jet engine was more significant for
many reasons; their impact on propulsion allowed aeroplanes to fly much faster, travel longer
distances and to provide thrust far more efficiently.Standard aerodynamic designs of
aeroplanes had to be entirely rethought in order for the aeroplane to survive these speeds, and
new materials had to be invented to withstand the soaring pressures and temperatures of jet
flight. Not only that, but the jet aircraft has allowedflight to become commercialized, due to the
efficiency of this new technology;as a consequence our worldis more interlinked than ever
before, and flyingis now regarded as a common formof transportation within our global
society.
From what I learnt frommy research, by the end of the 18th century,the mind-set of the first
aeronautical engineers was a more adventurous one. Even after 1903, flying was regarded as an
adventure and a luxury. The pioneering age following1903 involveda great deal of racing and
bizarre records, such as playing tennis on a flyingaeroplane. This comes to show that the
technology of flight was still not taken very seriously; it was regarded as a luxury and only small
advancements tookplace with nothing strikingly advancing the technology of flight. The only
major leap before the jet engine was leaving the biplane wing design introduced by Octave
Chanute. The last Biplane to be mass produced was the Italian Fiat CR.42 Falco in May
193824.The evolution frombiplane to monoplane wing design was also a product of war
demand, with the Spanish civilwar underway and the Second World War at hand, European
nations and the USA were racing to evolvetheir aircraft and were vyingfor supremacy of the
skies.
In the intense aerial combat of the Second World Warthere was a huge demand fornew cutting
edge aeroplanes, with the Messerschmitt and the spitfire as prime examples of how war can be
the most pressing demand foraeronautical engineers. Unsurprisingly, the jet engine was
invented in the heat of the Second World War. This revolutionary invention, whichmixed
efficiency and power so well, wouldchange flight forever.
Today our global air travel market is one of the most technologically advanced of them all with
amazing new aeroplanes such as the A380 and the Boeing 787 being invented. We are entering
an age of exponential growth and advancement, howeverwith new breakthroughs come new
challenges. In our age, fuel efficiency,noise reduction, reduced maintenance and building costs,
increased safety and efficient propulsion are at the core of our thinking. Is the next
revolutionary invention- an eco-friendly,economical, super-efficient, sustainable, but powerful
propulsion system? With our depleting natural resources, it looks like it must be.

20. BIBLIOGRAPHY
Internet sources
1.Wikipedia (updated 2014) Propulsive efficiency-MechanicalEfficiency,
http://en.wikipedia.org/wiki/Propulsive_efficiency
2. Wikipedia (Updated 2014) Aerospace materials-History,
http://en.wikipedia.org/wiki/Aerospace_materials
3. Britannica Encyclopaedia website (2014), Leonardo Da Vinci Gallery,
http://www.britannica.com/EBchecked/media/95182/Leonardo-da-Vincis-plans-for-an-
ornithopter-a-flying-machine
4. History of Airships and Balloons, First Flight and the Montgolfier brothers,
http://inventors.about.com/od/astartinventions/ss/airship_2.htm
5. Hargrave: The Pioneers, Aviation and Aeromodelling Interdependent Evolutions and
Histories, http://inventors.about.com/od/astartinventions/ss/airship_2.htm
6. Aerospaceweb.org, Origins of Control Surfaces,
http://www.aerospaceweb.org/question/history/q0103.shtml
7. Elsecretodelospajaros, El-Boy Carriers,
https://elsecretodelospajaros.wordpress.com/2013/03/09/el-boy-carrier/
8. The Secret of Flight, Understanding why it is possible to fly,
http://secretofflight.wordpress.com/gliders-2/
9. Smithsonian National Air and Space Museum, The Breakthrough Concept,
http://airandspace.si.edu/exhibitions/wright-brothers/online/fly/1899/breakthrough.cfm
10. Aviastar, Langley Aerodrome, http://www.aviastar.org/air/usa/langley_aerodrome.php
11. Wikipedia Official Website, Landing Gear, http://en.wikipedia.org/wiki/Landing_gear
12. Shoreline Aviation( 2011) , Piston engine aircraft vs. Turboprop engine aircraft,
http://www.shorelineaviation.net/news---events/bid/50442/Piston-Engine-Aircraft-vs-
Turboprop-Engine-Aircraft
13. Official Wikipedia Website, Propulsive efficiency,
http://en.wikipedia.org/wiki/Propulsive_efficiency
14. Official Wikipedia website, Aerospace materials,
http://en.wikipedia.org/wiki/Aerospace_materials
Books and Journals
15. Yoseph Bar-Cohen (2014) HT materials, CRC PRESS: High Temperature Materials and
Mechanisms, p.5-7
16. Laurence K. Loftin Jr. (1985) The age of propellers, Quest for performance: The Evolution
of modern aircraft, p. 103-110, 152-153

21. 17. Rowland White (2013), The first Bird Imitations, In. Bobby Birchall (des.) TRANSWORLD
PUBLISHERS The Big book of flight, p. 8-15.
18. John D. Anderson (2011), Chapter 1: The First Aeronautical engineers, Chapter 5: Aerofoils,
wings and other aerodynamics shapes, Chapter 9: Propulsion. In. Anne T. Brown, Lyn
Beamesderfer and Scott Amerman (eds.) Mc Graw Hill Introduction to flight , p. 1-35, 182-226,
475-499.
Eric Brown (2007),
19. It is utter nonsense to believe flying machines will ever work, In. Amber Tokeley, and
Sarah Sherlock (eds.)DK: The colour encyclopaedia of incredible aeroplanes, P. 6-8
Airbus Official Website, A350 XWB, http://www.a350xwb.com/advanced/wing/#first-in-
composite-wing.
20. Types of Super Alloys (2013), Ed. Sam Zhang, Dongliang Zhao, Aerospace Materials
Handbook.
21. Chapter 7 Materials Developments in Aeroengine gas turbines (2001), Ed. David Clark,
Steve Bold, Aerospace materials
22. History of the Airbreathing Jet engine (2014), Saeed Farokhi, Aircraft Propulsion
23. History of Engines (2008), Saeed Farokhi, Aircraft propulsion and gas turbine engines
24. Early Fighters (2000), Christopher Chant, ISLAND BOOKS, The world's greatest aircraft, p
12-62
25. Richard Holmes (2013), KNOPF DOUBLEDAY, Falling upwards: How we took the air
Audio-visuals
26.CFM International, How does a turbofan CFM567 engine work,
https://www.youtube.com/watch?v=_LaKlE2h3Jw
27. Mohammad Tawfik (2014), Airfoils and Wings: Thickness Ratio,
https://www.youtube.com/watch?v=qgJBIZABWeM