Physics of Helicopters
By: Jais Abecassis
The great Italian Leonardo Da Vinci had
used his inventive mind to create the ﬁrst
drawing of what we know today as the
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
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 Leonardo Da Vinci’s ﬁrst sketch of a helicopter
tremendously and are used for many
different purposes today.
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.
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 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
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
The motor blades
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 The fuselage tends to spin
when the helicopter is hovering or anti-clockwise
when its traveling at a high speed
and this is when the anti-torque
medals are mostly used.
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.