The great Italian Leonardo Da Vinci had used his inventive mind to create the first drawing of what we know today as the helicopter.
Many of great physicians have attempted to develop models of the helicopter but they were ALL missing 2 essential components: a true understanding of the nature of lift as well as an adequate engine.
In 1907, two brothers, Jaques and Louis Breguet, with the help of professor Charles Richer created the gyroplane no.1 which hovered for a few seconds.
Since then helicopters have evolved tremendously and are used for many different purposes today.
Leonardo Da Vinci’s first sketch of a helicopter
In order for an aircraft to take off, it needs to create lift. Lift is necessary because it a force that allows the aircraft to overcome its weight which is created by gravity.
These two forces oppose each other hence, the heavier the helicopter, the more lift is required.
Lift is the force which allows the aircraft to move vertically, for the helicopter to move forward and backward thrust and drag is required.
Thrust is the force which pushes the aircraft forward. Continuous thrust is required due to wind resistance also known as drag.
Lift Thrust Drag Weight Same principle for helicopters
What makes up a helicopter?
A helicopter consists of many different and important parts. The blades at the top of the helicopter are, as one, called the main rotor. The main rotor could range anywhere from 2 to 8 blades
The tail rotor is located at the rear of the helicopter. Tail rotors could range from 2-4 blades. Recently, helicopters were developed which do not have a tail rotor. These special helicopters are called NOTAR helicopters (NO TAil Rotor).
Inside the cockpit...
The collective changes the angle of the blades. This is necessary to control to aircraft. It is located on the left side of the pilot and is held by the left hand.
On the collective is the throttle. It twists in a clockwise direction.
The cyclic is the most important part of the helicopter. This controls the rotor disk. (ALL the blades on the aircraft are connected to the rotor disk.) It is located in front of the pilot.
The anti-torque pedals are located at the feet of the pilot.
How does a helicopter work?
As the blades turn in a counter clockwise direction, air flows underneath them, similar to air flowing beneath the wings of a plane.
When the blades are spinning, there is an increase in pressure below the blades, and a decrease of pressure above it.
As the rotor blades turn, a relative wind is created in the opposite direction of the rotor system.
When more lift is wanted to take off, the collective is pulled upward increasing the angle at which each individual blade spins at.
How a helicopter works continued...
At the same time as the blades are turning, torque is created which cause the cabin to turn in a clockwise direction
The tail rotor produces thrust to oppose the torque created and it also helps prevent the helicopter from turning in the opposite direction as the main rotor. The anti-torque pedals are used to control the thrust of the tail rotor.
The most torque is generated when the helicopter is hovering or when its traveling at a high speed and this is when the anti-torque medals are mostly used.
The motor blades spin clockwise The fuselage tends to spin anti-clockwise
How a helicopter works continued...
Unlike a plane, a helicopter has the ability to move 360 degrees.
Once the helicopter is in the air, it has the ability to “aim” its thrust. According to Newton’s Third Law, “every action as an equal and opposite reaction.
He does this using the cyclic. The pilot points the cyclic in his intended direction, by doing so, he changes the angle of the rotator disk. The disk points the thrust in the opposite direction of where you want to go. This action causes a reaction which pushes the helicopter in the desired direction.
Types of drag
There are 3 types of drag that a pilot could experience during flight
The first type is called Profile Drag
This is the frictional resistance of the blades passing through the air. The angle of attack (the angle at which the blades are changed to create lift) does not significantly affect this type of drag.
The second type is called Induce Drag
This type of drag is created when the extra air at the end of the blades form a vertex causing a slight decrease in pressure below the blade which therefore decreases lift.
The final type of drag is called Parasite Drag
This drag is formed when any object is affecting the aerodynamics of the aircraft. This occurs all the time. When the windshield is dirty there is a slight amount of parasite drag. As well as when rescue helicopters carry water under it, there is more resistance hence more parasite drag.
Throughout our project, we’ve learned the basics of helicopter flight. We have learned how lift is created through the blades, how a dusty exterior can create more drag, and many other interesting points. This project really opened our eyes to what it takes to fly a helicopter, although we only covered the basics of flight, where as there are so many other things to take into consideration.