
English: 
Hello, welcome to my talk on the history of
aerodynamics, Part 2, the history of further explorations of
aerodynamics in the 19th century and beyond. Here the 'beyond'
is just a few years into the 20th century.
The history of aerodynamics is not the fully
same as the history of basic fluid
dynamics
basically fully established in the first
half of the 18th century the
establishment
of the labia stocks equation but
the exploration in aerodynamics
for developing flying machine was
the ongoing with the attempt to
understand

English: 
Hello, welcome to my talk on the history of
aerodynamics, Part 2, the history of further explorations of
aerodynamics in the 19th century and beyond. Here the 'beyond'
is just a few years into the 20th century.
The history of aerodynamics is not the fully
same as the history of basic fluid dynamics,
basically fully established in the first half of the 18th century,
the establishment of the Navier-Stokes equation, but
the exploration in aerodynamics for developing flying machine was
still ongoing, with the attempt to understand

English: 
the generation of lift and drag on the flying bodies.
It is interesting to see there was no much technology transfer from the general
fluid dynamics to the field of applied aerodynamics
before the 20th century.
A good example is that the first use of
Bernoulli's equation in the aerodynamic literature
occurred in a paper published in Oct 1904.
In this presentation, I will talk about the history in two different lines:
the history of the theoretical aerodynamics
and flow dynamics and of the experimental aerodynamics or applied
aerodynamics. In the first part the main focus would

English: 
the generation of lift and drug
on the flying bodies it is
interesting to see there was no much
technology transfer from the general
flow dynamics
to the field of applied aerodynamics
before the 20th century a good
example is that the first use of
bernoulli's equation in the aerodynamic
literature
occurred in a paper published in
october 1904
in this presentation i will talk
about the history in two different lines
the history of the theoretical
aerodynamics
and the flow dynamics and of the
experimental aerodynamics or applied
aerodynamics
in the first part the main focus would

English: 
be the establishment
of the fourth floor dynamics equation
and the attempt for solving the flow
dynamics
equation especially on how to
mathematically calculate the force
the lift of the flying bodies
since euler equation in 1757
it took more than 65 years
that the researchers started to figure
out
how to include the fluid viscose force
into the flow dynamic equation
the first attempt was navier in 1822
who employed the pure molecular force
as their fluid with ghost force for
deriving the
complete through dynamic equation
in 1827 kochi took

English: 
be the establishment of the full fluid dynamics equation
and the attempts for solving the fluid dynamics equation,
especially on how to mathematically calculate the force,
the lift of the flying bodies.
Since Euler equation in 1757, it took more than 65 years
that the researchers started to figure out
how to include the fluid viscous force into the fluid dynamic equation.
The first attempt was Navier in 1822, who employed the pure molecular force
as the fluid viscous force for deriving the
complete fluid dynamic equation.
In 1827 Cauchy took

English: 
the fluid as the perfect inelastic body and introduced the symmetric strain stress,
which was adopted from his laws of motion for elastic bodies.
In 1829 Poisson took the fluids as the temporary solids,
together with the introduction of the pressure
into the symmetric stress tensor.
In 1834 Saint-Venant used the concept of molecular, slides and approximations
to derived fluid the dynamics equation;
and in 1845 Stokes
derived the full dynamic equation by employing the Cauchy's symmetric stress
Tensor. His derivation is in a very similar
form as we see in many textbooks.

English: 
the fluid as the perfect inelastic body
and introduced the strand stress
which was adopted from his laws of
motion for elastic bodies
in 1829 poisson took
the flute as the temporary started
together with the introduction of the
pressure
into the symmetric stress tensor
in 1834 cenvalang
used the concept of molecular
slides and approximations
to derived through the dynamics equation
and in 1845 stokes
derived the fourth dynamic equation by
employing the cauchy's symmetric stress
tensor
its derivation is in a very similar

English: 
form as we see in many texts book
in 1934 navier stock's equation was
first learned
when planta gave lectures on
fundamentals
of hydro and arrow mechanics
according to the reference to here
harman wong m hodge was a german
physicist
and physician and he made his
contributions
to the modern aerodynamics
in 1858 he studied
the difference between the irrotational
and the rotational flows and
he could basically employ the
concept of vorticity and
vortex filament water sheet
to represent the feature of notation of

English: 
In 1934 Navier-Stokes equation was
first named when Prandtl gave lectures on
'Fundamentals of Hydro- and Aero-mechanics'.
according to the reference [2] here.
Hermann von Helmholtz was a German physicist
and physician, and he made his contributions
to the modern aerodynamics.
In 1858 he studied
the difference between the irrotational and the rotational flows,
and he could basically employ the concept of vorticity and
vortex filament/vortex sheet to represent the feature of rotational flows.

English: 
rows
he could use the irrotational flows
plus vorticities to represent
the real flows is more important the
contribution
would be the three hemholes waters
syrians for the behavior of the
vorticities in the invasive flood
the stance of the vortex tube does not
vary with time through the element
lying on vortex 9
at some instant could continue to lie
on that vertex 9.
the fluid elements initially free of the
vorticities
remain free of verticity
he further studied the mathematical
lecture of
the vorticity water experiments and
vortex sheet which lead to

English: 
He could use the 'irrotational flows
+ vorticities' to represent the real flows. His more important
contribution would be the three Helmholtz vortex
theorems for the behavior of the vorticities in the inviscid fluid.
- the strength of the vortex tube does not vary with time;
- fluid element
lying on a vortex line at some instant could continue to lie
on that vertex line.
- the fluid elements initially free of the
Vorticities remain free of vorticity.
He further studied the mathematical nature of
the vorticity, vortex filaments and vortex sheet, which led to

English: 
the development of the cell called
the surface of discontinuity in
we see the fruit which was published
in 1868
in two days application the physical
symbol layer and the wake around an
aerofoil can be expressed using the
vortex
sheet for simplifying and solving the
problem
see this picture here as such
the viscose effect around the aerofoil
can
be included in the analysis of
invasive flows
shortly after the hem hose paper
in 1868 and the concept
of the surface of discontinuities
some researchers saw this may

English: 
the development of the so-called the 'surface of discontinuity' in
inviscid fluid, which was published in 1868.
In today's application, the physical thin boundary layer and the wake around an
aerofoil can be expressed using the vortex
sheet for simplifying and solving the problem,
see this picture here. As such, the viscous effect around the aerofoil
can be included in the analysis of
inviscid flows.
Shortly after the Helmholtz' paper in 1868 and the concept
of the surface of discontinuities, some researchers saw this might

English: 
provide a method for predicting the aerodynamic
drag on bodies, so to solve the zero-drag problem,
the D'Alembert paradox.
In 1869, Kirchhoff
first considered the force perpendicularly
exerted on a flat plate, see here. From the picture.
We can see a large region of 'dead air' behind the flat plate,
and for this it can be understood the difference
between the higher and lower pressures on both sides
of the plate would create a drag force on the plate. But
Kirchhoff did not calculate the force for the case
of the inclined plate.

English: 
provide a method for predicting the
aerodynamic
drug on bodies so to
solve the zero drug problem
the the long bed paradox
1869 job
first considered the force
perpendicularly
excited on a flat plate
see here from the picture
we can see a large region
of dead air behind the front plate
and for this it can be understood the
difference
between the higher and the lower
pleasures on both sides
of the plate would create
a jack force on the plate but the
ketchup
did not calculate the force for the case

English: 
In 1876 Lord Rayleigh, the 1904 Nobel Laureate in physics for his discovery of
Argon, independently examined the same problem
using the same concept, and he managed to obtain the
normal force coefficient CN, given at this.
this might not be correct in today's understanding,
but it was a good attempt to mathematically
calculate the fluid drag. In today's understanding the flow
Pattern would not be correct, since
in a small angle of attack, due to the fluid viscosity, the flow on the upper
surface would be fully attached to the surface,

English: 
of the inclined plate
in 1876 lord the lady
the 1904 lobbia lorded
in physics for his discovery of
argent independently examined the same
problem
using the same concept and he
managed to obtain the
normal force coefficient cn
given at this this
might not be correct in today's
understanding
but it was a good attempt to
mathematically
calculate the fluid drug
in today's understanding the flow
pattern
would not be correct since
in a small angle of attack due to the
fluid viscosity the flow on the upper
surface
would be fully attached to the surface

English: 
only in the cases of very large
angles of attack the flow on the up
surface
would be fully separated but
it would be more complicated for the
flow
above the upper surface rather than the
simplification
as the dead air
yourself warrington business was a
french
mathematician and physicist who
proposed the bosnica's hypothesis
on eddie viscosity he actually
reported the idea in 1872
and published it in 1877
in which he reasoned that the turbulent
flow could be sedia represented
by the average flow but as

English: 
only in the cases of very large angles of attack, the flow on the upper
Surface would be fully separated, but
it would be more complicated for the flow
above the upper surface, rather than the simplification
as the 'dead air'.
Joseph Valentin Boussinesq was a French
mathematician and physicist, who proposed the Boussinesq's hypothesis
on eddy viscosity. He actually reported the idea in 1872
and published it in 1877, in which he reasoned that the turbulent
flow could be still represented by the average flow, but it's

English: 
viscosity, the artificial viscosity, would be greatly increased, a relation
would be given as this, as the Boussinesqís hypothesis.
But it must be noted Boussinesq did not carry out the averaging as
Reynolds did. It is well known today in the turbulence
Modelling, the expression for the Reynolds stresses
is often expressed as this, here k is the turbulent
kinetic energy and MU_t is the eddy viscosity.
A misunderstanding here is the Boussinesq's
eddy viscosity provided an answer for the Reynolds stress, but in fact,
Boussinesqís relation appeared 18 years earlier than the Reynolds stress, which
was published in 1895, see the next slide.

English: 
viscosity the artificial viscosity
would be greatly increased adoration
would be given as this as the postnessus
hypothesis
but it must be noted posness
did not carry out the averaging as the
nanos did
it is well known today in the turbulence
modeling
the expression for the nano suggest
is often expressed as this
here k is the turbulent
kinetic energy and the mu t
is the eddy viscosity
a misunderstanding here is the
posiniscus
eddy viscosity provided an answer
for the nano's suggest but in fact
us discuss relation appears 18 years
earlier than the nanos suggests which

English: 
And the Reynolds
did not link the Boussinesq's eddy viscosity
with the Reynolds stress tensor. According to Rodi from the reference [2]
here, it was Prandtl who in
1925 firstly linked the Reynolds stress tensor and the Boussinesq's
eddy viscosity together, a relation now being employed in most
popular turbulence models.
Osbourne Reynolds was an innovator in the understanding of fluid dynamics.
and in 1895 he employed the ensemble averaging approach for the
Navier-Stokes equation, in which he gave the averaging calculation as this.

English: 
was published in 1895
see the next slide and the nano
did not linger the business case at the
viscosity
with the nano's stress tensor
according to roddy from the reference 2
here
it was a prompter who in
1925 first three linked the
name of stress tensor and the postnessus
at the viscosity together elevation
now being employed in most
popular turbulence models
osbourne learners was an innovator
in the understanding of flow dynamics
at the in 1895 he employed the
ensemble averaging approach for the
navier stocks equation in which
he gave the averaging calculation at

English: 
this based only notes u bar here
is the velocity of x direction
at each instantaneous center of
gravity of the fruit element
delta v this expression itself
might not be very physical since the
denominator
sigma no has no physical meaning
but if we time a constant
delta v on both the numerator
and the denominator then we can see this
averaging velocity
is the momentum average velocity
and the nanos give the component the
moment
or the specific moment of the component
and this so he obtained the expression
for the
velocity as the average velocity u bar
plus the fluctuation velocity u plan

English: 
Based on Reynolds, u_bar here is the velocity of x direction
at each instantaneous center of gravity of the fluid element
DELTA_V, this expression itself might not be very physical, since the
denominator SIGMA RHO has no physical meaning,
but if we time a constant DELTA_V on both the numerator
and the denominator, then we can see this averaging velocity
is the momentum average velocity.
And Reynolds gave the component
Momentum or the specific momentum of the component
as this, so he obtained the expression for the
velocity as the average velocity u_bar plus the fluctuation velocity, u'.

English: 
if we look at the picture and here this
is
for an unsteady flow so the average
would be carried out on a short period
t here so the overall velocity
would be severe unsteady
and then nanos applied the averaging to
the
navier-stokes equation and due to the
non-linearity of the navier-stokes
equation
averaging the equation would need an
additional term
which is now named as the name of the
stress
given as the store i j equally minus
u plus i and u plan j average
so this is the specific nano stress
tensor
although the simple expression this term
contains all their turbulent information
for their topping the flow

English: 
if we look at the picture at here, this is
for an unsteady flow, so the average would be carried out on a short period
T here, so the overall velocity would be still unsteady,
and then Reynolds applied the averaging to the
Navier-Stokes equation, and due to the non-linearity of the Navier-Stokes
Equation, averaging the equation would lead an
additional term, which is now named as the Reynolds
stress, given as this, TAU_ij equal minus
u'_i and u'_j average, so this is the specific Reynolds stress tenor,
Although the simple expression, this term
contains all the turbulent information for the turbulent flows,

English: 
and it causes the tremendous
difficulties for serving the fluid
dynamic equation
ludwig pronter was a german flo
dynamicist
and engineer in 1904
planter reasoned that at the large
laners number
which is true for many practical flows
the velocity
transition from a certain value
away from the wall to zero
directly at the wall takes
place in a scene layer
see the layer detector
layer which is named as
the boundary layer by planter

English: 
and it causes the tremendous difficulties for solving the fluid
dynamic equation.
Ludwig Prandtl was a German fluid dynamicist
and engineer. In 1904, Prandtl reasoned that at the large
Reynolds number (which is true for many practical flows),
the velocity transition from a certain value
away from the wall to zero directly at the wall takes
place in a thin layer, see the layer, the dark
layer, which is named as the boundary layer by Prandtl.

English: 
accordingly the flow domain
can be separated into two
regions the region
away from the solid boundary the flow
viscosity
can be neglected or the viscose effect
is
much smaller than the added viscosity
thus the flow can be treated as the
potential flows
the flow near the wall as seen
with corresponding air in which
the fluid with cause effect is important
so the boundary layer it's a very useful
concept and this concept that can be
used
for solving the problem
like the lumbar paradox
the flow past the simple structure such
as

English: 
Accordingly the flow domain can be separated into two regions:
- the region away from the solid boundary, the flow
Viscosity can be neglected or the viscous effect
Is much smaller than the eddy viscosity.
thus the flow can be treated as the potential flows;
- the flow near the wall, a thin viscous boundary layer, in which
the fluid viscous effect is important.
So the boundary layer is a very useful
concept and this concept can be used
for solving the problems: like the D'Alembert's paradox;
the flow past the simple structure, such as

English: 
air foils and the wall functions
this is very useful in the modern
cfd modeling where near the
wall boundaries wall functions are often
employed
for numerical modeling and the
transition from
nominal to turbulent the boundary layer
separation ether
in this slide kutta yokowski
crm is discussed
in 1902 kota in his
phd dissertation firstly showed
the possibility for calculating the air
foil lift
using the mathematical formulation
for instance for the the entire
arc effort he obtained the
lift given in this form

English: 
Airfoils; and the wall functions, this is very useful in the modern
CFD modelling, where near the wall boundaries, wall functions are often
Employed for numerical modelling;
and the transition from laminar to turbulent; the boundary layer
Separation, etc.
In this slide, Kutta-Joukowski theorem is discussed.
In 1902 Kutta in his PhD dissertation firstly showed
the possibility for calculating the airfoil lift
using the mathematical formulation,
for instance, for the Lilienthal's
arc airfoil, he obtained the lift, given in this form,

English: 
for this circular arc aerofoil
apply this to the lydian type circular
arc aerofoil
it gives the lift coefficient as
1.047 this is for the 2d aerofoil
compared to the leading entire stata
the coefficient 0.381
is 3d from the experiment data
even applied the 3d collection
quotas calculation would the b is d
larger than the experiment data and in
here
the lady enters data might be not
so accurate in 1906
zhikovsky provided a complicated
mathematical elevation to calculate
the lift gave the expression as
this the lift is proportional

English: 
for this circular arc aerofoil. Apply this to the Lilienthal's circular
arc aerofoil, it gives the lift coefficient as
1.047, this is for the 2D aerofoil. Compared to the Lilienthal's data,
the coefficient 0.381 in 3D from the experiment data.
Even applied the 3D correction, Kutta's calculation would be still
larger than the experiment data. And in here
the Lilienthal's data might be not so accurate.
In 1906 Joukowski provided a complicated mathematical derivation to calculate
the lift, gave the expression as this: the lift is proportional

English: 
to the circulation of the flow around the airfoil.
This is the exact formula we can see in many textbooks. These two developments
together formed the Kutta-Joukowski theorem, which is often regarded as the
fundamental theorem for the modern aerodynamics.
This is especially true for developing the method
for calculating the aeorfoil's lift before the CFD
was used to solve the Navier-Stokes equation.
According to the reference, the circulation
theory of lift is still widely used today, as we see in the modern panel
techniques for calculating lift values for aerofoil in inviscid flows,
such technologies are still being revised and

English: 
to the circulation of the flow around
the airfoil
this is the exact formula we can see
in many textbooks these two developments
together from the kuta yokowski
cerium which is often regarded as the
fundamental
syrian for the modern aerodynamics
this is especially true for developing
the method
for calculating the error foils left
before the cfd
was used to serve the navier stocks
equation
according to the reference the
circulation
theory of left is the sedea widely used
today as we see in the modern panel
techniques for calculated lift values
for aerofoil in invasive flows
such technologies as deer being devised
and

English: 
improved and thus the circulation theory
of
lift is there evolving today
after more than 100 years
since its first introduction
and based on the same reference lancast
was actually the first researcher
who proposed the flow past and aerofoil
can be expressed as the uniform flow
past the circulatory flow lancast
presented the idea in 1897
but the idea only appeared
in his popular book aerodynamics which
was published in 1907
the second aspect is the experimental
aerodynamics
of flow dynamics in 19th century
this is especially important for

English: 
Improved, and thus the circulation theory of
lift is still evolving today, after more than 100 years
since its first introduction.
And based on the same reference, Lancaster
was actually the first researcher who proposed the flow past an aerofoil
can be expressed as the uniform flow + a circulatory flow. Lancaster
presented the idea in 1897, but the idea only appeared
in his popular book, 'Aerodynamics', which was published in 1907.
The second aspect is the experimental aerodynamics
of fluid dynamics in 19th century. This is especially important for

English: 
applying aerodynamics or fluid dynamics, since
many pioneers sought all different ways to make the 'heavier-than
Air' flight possible. Although the fluid dynamics equation was
fully established in the first half of the 19th
century, solving the equation was impossible, thus the experimental
Aerodynamics became the only way for solving many
practical problems.
In the introduction for George Cayley, he was an English engineer, inventor
and aviator, not an aerodynamicist. The reason for this
is that he contributed little to the theoretical aerodynamics, even he used

English: 
applying
aerodynamics of low dynamics since
many pioneers sought all different
ways to make the heavier than
air of ride possible although the fluid
dynamics equation was
fully established in the first half of
the 19th
century solving the question was
impossible thus the experiment the
aerodynamics
become the only way for solving many
practical problems
in the introduction for george cady
he was an english engineer inventor
and aviator but then
another emissions the reason for this
is that he contributed later to the
theological aerodynamics even he used

English: 
both flight tests and the lab experiments
to gain an understanding of the basic aerodynamics.
- Cayley performed
the series measurements of the variation of lift
with different angles of attack to show the emphasis on the aerodynamic lift,
where other researchers might only be interested in drag.
- Cayley's basic concept of mechanism of lift on a fixed wing was
totally different from the mechanism of propulsion, like the Da Vinci's
aerial screw helicopter, this is a large leap in the advancement
of the technical aeronautics.
- Cayley was the first to appreciate

English: 
the both
flight tests and the lab experiments
to gain an understanding of the basic
error dynamics kelly formed
the serious measurement of the variation
of left
with different angle of attack to show
the emphasis on the aerodynamic left
where other researchers might
only be interested in drug
kerry's basic concept of magnesium
of lift on a flexed wing was
totally different from the mechanism of
proportion like the damages
earlier screw helicopter this
is a large lip in the advancement
of the technic aeronautics
kedi was the first to appreciate

English: 
the benefit of the cambered lifting surface for creating more lift
for the fixed wing flight.
- Cayley's idea concerning the drag on
different components on the vehicle, like the drag on the wing, drag
on the fuselage, which were quite consistent with our modern conception
of the parasite drag and induced drag.
In 1871 in Britain, Francis Wenham, following the unsatisfactory
experiments with the whirling-arm, in which
the moving air with the whirling-arm made the airspeed measurement very difficult,

English: 
the benefit of the cambered
lifting surface for creating more lift
for the fixed wing flight
carries idea concerning the drug on
different components on the vehicle
like the jack on the wings jack
on the fuselage which were quite
consistent with our modern conception
of the palestine drug and the induced
drug
in 1871 in britain france's
vietnam following the unsatisfactory
experiment
with the weeding arm in which
the moving air with the reading arm made
the airspeed measurement very difficult

English: 
so he persuaded the Aeronautical Society of Great Britain to raise the funds
to build the world's 1st wind tunnel: this wind tunnel had the duck
of 12 feet (3.6m), and a work section
18 inches times 18 inches, which is 0.47m*0.47m,
and the airspeed is 40 mph,
about 18 m/s in the cross section. In today's
terminology, this wind tunnel is an open jet wind tunnel.
Although the poor flow quality, the tests carried out in the wind tunnel could
show two significant results:
- at the small angle of attack
the lift force varies in proportion to the

English: 
so he proceeded the aeronautical society
of greater britain to write the funds
to build the world first wind tunnel
this winter had the duck
of 12 feet 3.6
meter and the work section
18 inches times 18 inches
which is 0.47 meter times
0.40 meter and the airspeed
is 40 miles per hour
about 18 meters per second in the
cross section in today's
terminology this ring turner is an
open jet wind tunnel although
the poor flow quality the tests
carried out in the wind tunnel could
show true significant
result at the small angle of attack
the lift force varies in proportional to
the

English: 
sine of the angle of attack, rather than the
square of the sine, which was indicated by Newton;
the wings of higher aspect ratio had higher lift to drag ratio (L/D)
than those of lower respect (ratio).
In the early 1880s, also in Britain, Horatio Phillips built a wind tunnel
of similar proportion, but with a steadier flow.
Using this wind tunnel, Philips could develop
and patent a series of cambered modern airfoils,
see the pictures here. And for the importance of the wind
tunnel, the Wright brothers made an important

English: 
sign of the angle of attack rather than
the
square of the sign which was
indicated by newton the wings
of high aspect ratio had higher lift
to drag ratio error over d
than those of law respect
in the early 1880s also in britain
malaysia phillips built an internal
of similar proportion but
with a steadier flow
using this internal philips could
develop
and patent a series of
cambered modern airfoil
see the pictures here
and for the importance of the wind
tunnel
the razer brothers made an important

English: 
decision in 1801 to build
their own wind tunnel and test
their wings rather than use the existing
data
which was the decisive step
which results in the initial successes
of the 1802 glider
and the huge success of the first
heavier than air flight
in 1903
in earlier 1880s
nanos perform a serious experiment
outflows
in pipes of different sizes
to examine the phenomenon of the flow
from nominal
to turbulent transition
in the data analysis nanos
use the different combinations of
the physical parameters and he could

English: 
decision in 1901 to build their own wind tunnel and test
their wings, rather than using the existing data,
It was the decisive step which resulted in the initial successes
of the 1902 gliders, and the huge success of the first
Heavier-than-air flight in 1903.
In earlier 1880s, Reynolds performed a series experiments of
flows in pipes of different sizes,
to examine the phenomenon of the flow from laminar
to turbulent transition. In the data analysis, Reynolds
used the different combinations of the physical parameters, and he could

English: 
finally
conclude one non-dimensional parameter
he named the k number in his publication
in 1883 this number
can be used to indicate the transition
from nominal to turbulent and
this k number was later named as
leno's number and in the publication
in 1895 he showed the experimental
result
for the laminar flow the nano's number
is smaller than 1900
nanos used the stable flow in the paper
for
the laminar flow and when the nano
number is
more than 2000 the flow becomes
turbulent
dynodes use unstable flow in the paper
this
experiment result is quite close to the
result

English: 
finally conclude one non-dimensional parameter,
he named the k number in his publication in 1883. This number
can be used to indicate the transition from laminar to turbulent, and
this k number was later named as Reynolds number. And in the publication
in 1895 he showed the experimental result:
for the laminar flow the Reynolds number is smaller than 1900,
Reynolds used the stable flow in the paper for
the laminar flow, and when the Reynolds number is
more than 2000, the flow becomes turbulent,
Reynolds used unstable flow in the paper. This
experiment result is quite close to the result

English: 
from what we take today as the critical
nameless number two thousand three
hundred
in today's understanding nano's number
becomes a very important parameter for
studying the
flow phenomena and from the
dimensional analysis the fluid pressure
left and the jug can be all
the function of the nano number
and the expressions of this aerodynamic
forces
would be normally given in the
non-dimensional form
as the nano's number is saved
author lydianta was the german pioneer
of variation as both researcher
and predictationer in application
lidianta as a researcher had been

English: 
from what we take today as the critical Reynolds number: 2300.
In today's understanding, Reynolds's number
becomes a very important parameter for studying the
flow phenomena, and from the dimensional analysis, the fluid pressure,
lift and drag can be all the function of the Reynolds number,
and the expressions of these aerodynamic forces
would be normally given in the non-dimensional form
as the Reynolds number itself.
Otto Lilienthal was the German pioneer of aviation, as both researcher
and practitioner in aviation. Lilienthal as a researcher had been

English: 
tested aerofoil with the reading arm
device
and later obtain the data from the other
side
in the wing he built the first set of
the data
in applied aerodynamics and
brought the data in a systematic
fashion the drug polar diagram
which respected the basic rules
of the fundamental flow dynamics
the data set was later used by others
including their writer brothers who
designed their 1900 and
lighting zero one gliders
lilianta's more important contribution
would
be the applied aerodynamics

English: 
tested aerofoil with the whirling-arm device
and later obtained the data from the outside
in the wind:
- he built the first set of the data
in applied aerodynamics and plotted the data in a systematic
fashion, the 'drag-polar-diagram', which respected the basic rules
of the fundamental flow dynamics;
- the dataset was later used by others,
including the Wright brothers, who designed their 1900 and
1901 gliders. Lilienthal's more important contribution
Would be the applied aerodynamics,

English: 
in which he played the other rules
inventor builder and the pilot
of the fourth platinik gliders
he himself had made more than 2000
glider flies and which
he lost his life in 1896
diriantha's successes in the glider
flight
had significantly inspired both
kuta through his phd supervisor
and jokowski for developing their
mathematical models for protecting the
lift of their foyer now
we know the kota yokowski cerium
the last piece of the mystery
aerodynamics
in understanding the heavier the airfly

English: 
in which he played the other roles: inventor, builder and the pilot
of the first practical gliders. He himself had made more than 2000
glider flights, and for which he lost his life in 1896.
Lilienthal's successes in the glider flights
had significantly inspired both Kutta (through his PhD supervisor)
and Joukowski for developing their mathematical models for predicting the
lift of the airfoils. Now we know the Kutta-Joukowski theorem,
the last piece of the mystery aerodynamics
in understanding the 'heavier-than-air' fly.

English: 
samuel appear upon the lonnie was an
american
as german physicist and aviation pioneer
nandi had become a series of
aerodynamic experiments in 1886
on a large wedding arm device
and the test data has been reported in
his book
experiments in aerodynamics which
was published in 1891
this was the important american
contributions to the aerodynamics
in the 19th century nanny's
contributions to aerodynamics in both
science
and engineering aspect
he explored the basic physical roles of
aerodynamics and demonstrated
scientifically the practical capability
of the powered heavier the air of light

English: 
Samuel Pierpont Langley was an American
as german, physicist and aviation pioneer. Langley had begun a series of
aerodynamic experiments in 1886 on a large whirling-arm device,
and the test data has been reported in his book
'Experiments in Aerodynamics', which was published in 1891.
This was the important American contributions to the aerodynamics
in the 19th century. Langley's contributions to aerodynamics in both
science and engineering aspects.
- he explored the basic physical roles of aerodynamics and demonstrated
scientifically the practicability of the powered 'heavier-than-air' flight.

English: 
- and he designed a series of flight machines
in order to confirm his conclusions from his whirling-arm data,
see this picture, the flying machine.
And the based on the reference, Langley's
most interesting and most controversy conclusion
from his experimental data was the 'Langley Law': the power required
for a vehicle to fly through the air decreases as the velocity increases,
which was based on his soaring measurements for the velocity less than
20 m/s. The calculation was wrong when compared to the practical applications.
Langley's contributions to aerodynamics
earned him the name: such as, NASA Langley Research Center; Langley Air

English: 
and he designed a series of ride
machines
in order to confirm his conclusions
from his winning arm data
see this picture the flying machine
and the based on the reference none is
most interesting and the most
controversy conclusion
from his experiment data was the lonely
law the power required
for a weaker to fly through the air
decreases as the velocity increases
which was based on his solving
measurements for velocity less than
20 meters per second the calculation
was wrong when compared to the platinic
applications
romney's contribution to aerodynamics
on him the name such as nasa
learning research center lonely air

English: 
force
base and some other names
in the last slide of the talk the red
brothers
flyers would be introduced in 1896
the legendary red brothers began the
interest
in the flying machine but the serious
study of the important information
did not begin until 1899.
in august 1899 the red brothers
constructed as more glider which
incorporated the wing wrap technique
for the larger control they invented
this
control technology in 1900
and 1901 the brothers used
the existing aerodynamic data in the

English: 
Force Base; and some other names...
In the last slide of the talk, the Wright brothers
flyers would be introduced.
- In 1896, the legendary Wright brothers began their
Interest in the flying machine, but the serious
study of the important information did not begin until 1899.
- In August 1899, the Wright brothers constructed a small glider, which
incorporated the wing wrapping technique for the lateral control, they invented
this control technology.
In 1900 and 1901 the brothers used the existing aerodynamic data in the

English: 
design of their gliders, but with no success.
- In 1901 after the test season, they were disappointed and discouraged
by the flight results. So they made their comments, such as:
'man would not fly for another 50 years', and another version would be: 'Not
within a thousand years would man ever fly'.
- In 1901 they built their own wind tunnel and started their test program in 1901
and 1902. This was the most important
decision they made which led to the new
remarkable success for glider in 1902;
- and on Dec 17 1903, the Wright brothers' flyer lifted into the

English: 
design of
their gliders but with no success
in 1901 after their test season
they were disappointed and discouraged
by the flight result
so they made their comments such as
man would not fly for another 50 years
and another washer would be not to
within a thousand
years would the man ever everfly
in 1801 they built their own wind tunnel
and started their test program in 1901
and
1902 this was the most important
decision
they made which led to the new
remarkable success for glider in
1902 and
on december 17 1803
the red brothers flyer lived into the

English: 
air
and flew for 12 seconds covering
120 feet over the over the ground
in a head wind this is actually heavier
than air flight
in the aviation history in which
the relative air speed is about 14.9
meters per second but the ground speed
is about
three meters per second and after that
more successful studies for example
less than a year in 1904
a four closed circuit flight was made
covering 1244 meters
in one minute 30 seconds
with the average speed 13.8
meters per second and more
successful stories this will be

English: 
air and flew for 12s, covering
120 ft over the ground in a head wind. This is actually heavier-
than-air flight in the aviation history, in which
the relative air speed is about 14.9 m/s, but the ground speed
is about 3m/s.
- And after that,
more successful stories, for example, less than a year, in 1904,
a full closed-circuit flight was made, covering 1,244 m
in 1min 30s, with the average speed 13.8m/s
- and more successful stories...
this will be discussed in my next talk.

English: 
discussed
in my next talk
you

English: 
A statement: 'All photos and drawings in this talk are either from Wikimedia Commons or my own works'.
