Helicopters are the true flying machines
They can take off and land without the need for our runway
They can hover in the air it can maneuver in any direction in a 360 degree space
This video will unveil the complexity in science behind flying a helicopter
After going through the physics behind the helicopter flying you will also understand why helicopter pilots are doing an incredibly complex job
Helicopters use the Airfoil principle to generate lift
When the blades rotate relative to the air the special airfoil shape will generate lift force and make them fly
the blades derive rotation from an engine more specifically a turbo shaft engine
The compressor sucks the air in and pressurizes it fuel is burned in this pressurized and hot air
The hot exhaust leaves the combustion chamber passes through a series of turbine stages and make them turn
There are two Sets of turbines one turbine set turns the compressor and the other set turns the helicopters rotor shaft
Jet Engines of Airplanes are used to generate thrust force
However the primary function of the helicopters jet engine is to turn the rotor shaft
The most challenging part in helicopter operation is its controls that means how can it fly forward?
how can it fly backward
sideward
Or how can it Take a turn
The answer is quite simple just rotate the helicopter towards the direction you want to move and just fly
When the helicopter is at an angle the Force produced by the blade is not vertical
The horizontal component of this Force will make the helicopter move in the desired Direction
the vertical component of the Blade Force will Balance the gravitational force
Now the real challenge is how to turn the helicopter in the desired way?
To learn the science behind helicopter turning we need to learn more about the airfoil principle
the lift produced by an airfoil varies with the angle of attack
Generally the greater the angle of attack the more the lift
Now think for a moment what happens if the one blade were at one angle of attack and others were at a different angle?
The lift forces acting on the blades will be different in this case
The variations in the lift forces will definitely result in a torque that can turn the helicopter
You can observe the beautiful blade motion required to achieve this non-uniform Lift Force distribution
It is clear that the blades must keep on changing angle of attack so that at one particular location the angle of attack is
always the same
Such complex Of the blades is easily achieved by a swash plate mechanism
Get an exploded view and understand the basic components first
The bottom Swash plate does not spin, but it can move and tilt as shown
A top swash plate is fitted on the bottom swash plate Via a bearing
So the top Swash plate kid inherit all the motion of Bottom Swash plate while at the same time it can rotate independently
Top swash Plate is attached to the rotor Shaft with the help of a driver. So the top swash plate will always move with the blades
The blades are connected to the top swashplate with the help of control Rods
The interesting thing about this arrangement is that just by tilting the bottom swashplate
We will be able to achieve the varying Angle Criterion of the blades
That means with this swashplate tilt
We will always be able to maintain a positive
Angle of attack at the rear and a negative angle at the front portion of the rotor disk
in short Swashplate tilting backwards produces a torque as shown
This kind of control is known as cyclic pitch
now back to the basic helicopter control
How will this torque affect the helicopters motion?
The most obvious answer is that the helicopter will turn forward and move as shown
Unfortunately this answer is completely wrong
What happens in reality is the helicopter will turn sideward as shown this is definitely a weird effect
By applying torque in One direction to a rotating object the object turns in Different direction
This effect is known as gyroscopic precession
Gyroscopic precession is not a new phenomenon of physics if you carefully apply Newton's second law of motion to rotary objects
You will be able to predict this phenomenon according to Newton's second law Force is the rate of change of linear momentum?
Similarly torque is rate of change of angular Momentum
Let's consider this rotating blade. It will have an angular momentum as shown now
assume that the helicopter has tilted as shown due to some torque action if
You victoria lee subtract the first angular momentum from the second you can figure out the torque required for this operation it
Is interesting to note that to turn the helicopter forward the torque applied should be towards sidewards that means to tilt the helicopter?
Forward the Swash plate should tilt sidewards as shown
You can again verify from Newton's second law of motion
that if you keep the front portion at negative angle of attack and the back portion at positive Angle the
Helicopter will simply turn sidewards
Gyroscopic precession is a truly intriguing phenomenon, but it conforms perfectly with Newton's second law of motion
if you just lift the bottom swashplate without tilting it you can see how the angle of attack of all three blades will vary by
the same amount
This means that the helicopter lift Force will be the same in all three
Blades and the helicopter can move up or down without any tilt
Such blade control is known as collective pitch
If you have ever seen a helicopter you are all sure to have seen a tail rotor
every single rotor helicopter needs this tail rotor for effective operation
Without the tail rotor the helicopter fuselage would have spun as shown
This is due to a consequence of Newton's third law of motion
To Understand it let's focus on the Force transmission part of the rotor
We know the rotor gets the force of rotation Via a bevel gear connected to the engine the engine?
Bevel gear Transmits Force to the rotor bevel gear as shown however according to Newton's third law of motion
the Rotor bevel gear should Transmit an equal and opposite Force to the engine bevel gear
This reaction Force will make the whole helicopter turn opposite to the blade rotation along the helicopter center of gravity
The function of the tail rotor is to prevent such helicopter rotation by producing a force at the tail
By properly adjusting pitch angle of the tail rotor
Blades the Pilot can easily manipulate the tail rotor Force this way with the help of the tail rotor
Yaw motion of the helicopter can also be achieved
All the physics behind helicopter operation means that flying a helicopter is a truly challenging task
minut variations in Blade Angles make huge variations in Helicopter Behavior
Often the pilot has to do two or more operations together to achieve the desired motion
moreover the helicopter does not respond instantaneously to your inputs so the pilot should possess a good sense of balance and
coordination to navigate the Helicopter properly
Your support at patreon.com enables us to make further free educational videos, please support us at patreon.com
Thank you