- On December 17th 1903, the history of the aviation
was changed forever when the Wright brothers
made the world's first successful flight.
You might think that they're design was so simple.
The propellors move the aircraft forward,
the wings produce the lift
and the aircraft stays in the air.
But when you examine it closely,
you will amazed but the numerous ingenuous technologies
these high school dropouts developed 100 years ago.
(upbeat music)
Their design was so complete
that even the current modern aircraft
used the same principles of flight.
First thing's first, to make an aircraft fly
you have to first overcome the pull of gravity,
or in other words, you have to produce a lift force.
The Wright brothers borrowed the idea
of lift generation from their own
earlier experience on gliders.
They knew that when air float over a curved surface,
it generated a lift force.
The higher the speed, the more would be the lift force.
An increase in angle of attack
also increase the lift force.
How is this lift generated?
That's a topic for another video.
To make the aircraft move forward,
two propellor blades were used.
They produced thrust force,
again, from the same airfoil principle.
The thin propellor blades
were a clever design choice.
Until then, the common belief
was that an aircraft propellor
should be something like that
of a ship's propellor.
However, the Wright brothers proved
that to work efficiently in air,
a high speed narrow blade was the ideal choice.
Moreover, you will notice that the blades
were rotating in opposite directions.
This was another crucial design decision.
Without this, control of the aircraft
would not have been possible.
We will learn about that at the end of the video.
The blades were driven by an engine which sat on the wing.
To fly an aircraft, you have to obey
the following force equations of flight.
To come up with an aircraft design
which satisfy these equations,
the Wright brothers developed
their own lift data by abandoning
all the wrong lift data that was available at that time.
The Wright brothers' wing
had a top point near the leading edge.
This design produced more lift
than the top at centre design used at that time.
With an optimized wing design alone,
this aircraft would not lift from the ground.
The Wright brothers realized that the existing
heavy automobile engines being used
were the main villains.
They had to make the engine lighter
without compromising its power output.
Only a powerful engine could give
the aircraft a good speed.
As explained earlier, the more the speed
the more the lift.
Unable to find any such engine,
with the help of their mechanic,
the Wright brothers designed
and built their own engine.
A light-weight, 12 horse power petrol engine.
Even before the new engine development,
the Wright brothers had calculated
that they needed an engine
of less than 200 pounds in weight,
with at least eight horse power
to meet the equations of flight.
To reduce weight, they even
cast the crank case with aluminum,
a first at that time.
They painted the crank case black
so that their competitors would not know
about the construction material.
You can see the details of the chain and sprocket
mechanism used to transfer power
from the engine to the propellor blades.
With this design, at proper airplane speed,
the lift force would overtake the gravitational pull,
and they would have take-off.
Did you notice a rail track in this visual?
That was another clever design decision
from the Wright brothers.
They knew that it was impossible
to get a good airplane speed in the sandy terrain,
so they used a 60 foot long
rail track arrangement for a smooth take-off.
The Wright brothers' main innovation
was the development of successful flight controls.
Aircraft crashes were a common issue
in those days, and nobody knew how to control them.
To have a successfully flight,
the Wrights had to control their plane in three axes.
Pitch,
roll,
and yaw.
They again relied on the principles
of the airfoil to accomplish this task.
To pitch the airplane, the right flyer
had an elevator arrangement at the front.
You can see that by moving this lever,
a rope mechanism change the angle of the elevator.
If the elevator's rotated up,
there would be an upward lift force
as per the air flow principle.
The torque produced by this lift force
could push the whole aircraft up as shown.
To push the aircraft nose down,
they just did the reverse.
In modern airplanes the elevators are fitted at the back.
To roll the aircraft, Wilbur Wright had a great idea:
wing warping.
It was clear that by twisting
the wing along its length at one end,
the angle of attack would be positive
and the other end, it would be negative.
This would obviously create a lift differential
and the airplane would roll.
To the understand how the Wright brothers
practically achieved the wing warping,
let's have a look at this animation.
The pilot controls a cradle, using his hip,
which in turn controls two separate cables attached to it.
The cable movement makes the wing warp
through a clever mechanism.
This is a brilliant mechanism.
We need a separate, dedicated video
to understand the details of it.
In modern aircraft, ailerons are used
to generate the lift differential.
However, when the Wright brothers
tried to roll the aircraft using wing warping,
the result was disastrous.
They noticed that along with the rolling,
the airplane took an unintended turn as shown.
They called it a "steering reversal problem."
This phenomenon is now called, "adverse yaw."
The physics behind the adverse yaw
are now well understood.
The airflow above the high angle wing region
produces high drag.
On the other tip, the drag force is low.
The difference in the drag force
makes the airplane yaw as shown.
The Wright brothers overcame this issue
with the help of a rudder arrangement.
If the aircraft was yawing in this way,
they turn the rudder as shown,
in such a way that the torque produced by the rudder
would exactly cancel the adverse yaw torque.
Here the Wright brothers made another smart move.
Since the rudder had to be operated
whenever there was wing warping,
they connected the rudder
and wing warping controls together.
Both these motions were simultaneously operated
from the hip control.
By using these controls effectively,
the Wright brothers were able to give the aircraft
the stability needed.
Pitch the aircraft to climb up or climb down,
and make a smooth turn by banking the aircraft.
Now back to the interesting question
posed in the middle of the video.
Why did the Wright brothers
use opposite direction of rotation for the blades?
This was to cancel the gyroscope effect of a rotating wheel.
Any rotating object has an angular momentum.
Assume the Wright brothers designed the aircraft
with the blade spinning in the same direction.
Now the pilot decides to pitch the aircraft
by lowering the elevator.
The lowering of the elevators
would obviously produce a torque as shown.
However, the airplane would not pitch upwards as expected
due to the angular momentum of the blades.
Instead, it would take an unexpected side turn as shown.
This unexpected phenomenon
is known as gyroscopic procession.
Gyroscopic procession conforms perfectly
with Newton's Second Law of Motion.
You can see that the direction of change
in angular momentum is the same
as that of the torque applied.
The only way to overcome such unexpected behavior
is by eliminating the very cause of it:
the angular momentum of the spinning blades.
That is exactly what the Wright brothers did
with two blades spinning in opposite directions.
It is astonishing to discover
that the Wright brothers thought about
such detailed engineering points,
despite their limited formal education.
Did you notice that the pilot's position
was not in the middle of the aircraft?
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if you are astonished by the marvelous engineering feats
that the Wright brothers accomplished.
Also, let us know in the comments box
why you think the Wright brothers
decided to position the pilot slightly off-center.
Thank you.