Drones | The complete flight dynamics
Summary
TLDRThis video script delves into the exhilarating world of drone flight mechanics. It explains how BLDC outrunner motors and propeller blades generate lift, enabling takeoff and hovering. The script clarifies the importance of counter-rotating propellers to neutralize torque and maintain stability. It also details how manipulating motor speeds controls yaw, pitch, and roll for directional control. Furthermore, it explores the physics behind moving the drone forward, sideways, and in circular patterns, providing a comprehensive look at the fascinating dynamics of quadcopter flight.
Takeaways
- 🚁 Flying a drone involves complex maneuvers and understanding its flight mechanics is essential for effective operation.
- 🛫 Drones utilize BLDC outrunner motors with propeller blades attached directly to the motor cover for lift generation.
- 🔄 The airfoil principle is key in drone flight, as it allows the propeller blades to generate lift force when air flows over them.
- 📈 The controller adjusts motor speed, which in turn affects the lift force produced by the propellers; higher speed results in greater lift.
- 🛫 Takeoff in a drone is achieved by increasing rotor speed until the collective lift force overcomes the drone's weight.
- 💫 Hovering is maintained by balancing the lift force with the drone's weight, achieved by adjusting rotor speed.
- 🔄 Opposing rotation of diagonally opposite propellers is necessary to counteract reaction torque and prevent the drone from spinning.
- 🌀 Yaw motion is achieved by varying the speed of one diagonal pair of propellers compared to the other, creating a net torque that spins the drone.
- 📊 Pitch and roll are controlled by adjusting the speed of the front and back, or side propellers respectively, to create a net torque that maneuvers the drone.
- 🔄 In both roll and pitch operations, the reaction torques from the motors cancel each other out, ensuring stable drone operation.
- 🌐 To move the drone forward or sideward, it must be pitched or rolled and then balanced vertically to counteract the horizontal component of the propeller force.
Q & A
What is the main purpose of the propeller blades on a drone?
-The propeller blades on a drone are the most important part, as they produce lift force when air flows over them due to the airfoil principle, allowing the drone to take off, hover, and maneuver.
How do BLDC motors, specifically outrunner types, contribute to a drone's flight mechanics?
-BLDC outrunner motors are used in drones because they have propeller blades attached directly to the motor cover, which allows for efficient conversion of electrical energy into mechanical energy to generate lift.
What is the significance of the lift force produced by the drone's blades?
-The lift force produced by the drone's blades is crucial for overcoming the weight of the drone, enabling it to lift off the ground, hover, and perform various maneuvers.
How does the controller modify the drone's flight?
-The controller is used to modify the motor speed; a greater blade speed results in a greater lift force, allowing the drone to change its altitude and perform different movements.
What is the 'climbing stage' in drone flight?
-The 'climbing stage' is when the rotor speed is increased to the point where the collective lift force produced by the blades overcomes the weight of the drone, causing it to lift off the ground.
Why do opposite pairs of propellers on a drone rotate in different directions?
-Opposite pairs of propellers rotate in different directions to counteract the reaction torque that would otherwise cause the drone body to spin, maintaining stability during flight.
What is the role of Newton's third law of motion in drone flight mechanics?
-Newton's third law of motion explains that for every action, there is an equal and opposite reaction. In drone flight, this means that as the rotors apply a torque to the air, the stator receives an equal and opposite torque, which must be balanced to prevent the drone from spinning.
How does a drone achieve yaw motion?
-Yaw motion is achieved by rotating one diagonal pair of propellers at one speed and the other pair at a different speed, creating a net reaction torque that causes the drone body to spin.
What controls the pitch and roll of a drone?
-The pitch and roll of a drone are controlled by the same stick on the remote control. By spinning the front and back propellers at different speeds, the drone pitches, and by spinning the side pairs at different speeds, the drone rolls.
How can a drone move in a perfect circle?
-A drone can move in a perfect circle by applying a force that is always perpendicular to its velocity, which can be achieved by combining pitch and roll movements to create the necessary centripetal force.
How does a drone maintain balance during forward or sideward movement?
-To maintain balance during forward or sideward movement, the drone must balance the gravitational force with the vertical component of the propeller force, and the horizontal component of the propeller force must be matched by the drag force as the drone moves.
Outlines
🚁 Understanding Drone Mechanics and Takeoff
This paragraph delves into the mechanics of flying a drone, starting with the basics of takeoff and hovering. It explains the importance of propeller blades and how they generate lift using the airfoil principle. The role of the controller in adjusting motor speed to control lift is highlighted, with an explanation of how increasing rotor speed leads to takeoff and how balancing lift and weight results in hovering. The paragraph also addresses the counter-rotation of diagonally opposite propellers to negate reaction torque and maintain drone stability. Finally, it touches on the principles behind drone maneuvers like yaw, pitch, and roll, and how these are achieved by adjusting the speed of different propellers to create net torque.
🔄 Advanced Drone Movements and Physics
The second paragraph explores the advanced concepts of drone movement, including pitch, roll, and the physics behind them. It discusses how changing the speed of propellers can create a net torque that results in pitching or rolling the drone. The paragraph explains how the drone's design ensures that reaction torques cancel out, contributing to stable operation. It also covers how to move the drone forward or sideways by pitching or rolling and balancing the drone vertically to counteract horizontal forces. The concept of circular motion is introduced, explaining how a force perpendicular to the drone's velocity can make it turn in a circle. The paragraph concludes with an invitation to learn more about drone dynamics in other videos of the series.
Mindmap
Keywords
💡Drone
💡BLDC Motors
💡Propeller Blades
💡Airfoil Principle
💡Controller
💡Takeoff
💡Hovering
💡Reaction Torque
💡Yaw Motion
💡Pitch and Roll
💡Climbing Stage
💡Drag Force
💡Circular Motion
Highlights
Drones use BLDC (Brushless Direct Current) motors, specifically outrunner types, with propeller blades attached to the motor cover.
Propeller blades are crucial for drone flight, producing lift force through the airfoil principle.
The blade design ensures lift force direction consistency, allowing for total lift force representation.
The controller adjusts motor speed to modify lift force, with higher blade speed generating more lift.
Takeoff involves increasing rotor speed until the collective lift force overcomes the drone's weight.
Drones hover by balancing lift force with the drone's weight after achieving necessary height.
Opposite rotation of diagonally opposite propellers prevents the drone body from spinning.
Newton's third law of motion explains the reaction torque and its effect on drone body stability.
Yaw motion is achieved by varying the speed of diagonal propeller pairs, creating non-cancelled reaction torque.
Pitch and roll are controlled by adjusting the speed of front/back or side propeller pairs, respectively.
In roll and pitch operations, the net reaction torque from motors sums up to zero for stable operation.
Climbing a drone is demonstrated by pitching it forward and then balancing the propeller speeds.
Forward or sideward motion is achieved by pitching or rolling the drone and balancing it vertically.
The horizontal component of propeller force and drag force balance for horizontal drone movement.
Circular motion of a drone is possible by applying a force perpendicular to its velocity.
The video concludes by inviting viewers to explore more drone-related content and support the channel.
Transcripts
flying a drone is great fun
you can do a nice takeoff like this
you can hover it
turn it into any axis you want
and even show off to your friends with
complex maneuvers but how do the flight
mechanics actually work
if you've ever found yourself wondering
that that this video is for you
drones use bldc motors which are
outrunner types
as you can see the propeller blades are
attached to the cover of the motor the
propeller blades are the most important
part of the drone
each cross section of the blade produces
a lift force when air flows over the
blade due to the airfoil principle
the blade is designed such a way that
the lift force produced along the length
will be in the same direction on both
parts of the blades allowing us to
represent the total lift force produced
by the drone blade as shown
the controller is used to modify the
motor speed the greater the blade speed
the greater the lift force
so how do we get from being on land to
being sky high
it's time for takeoff
just increase the rotor speed
as the collective lift force produced by
the blades overcomes the weight of the
drone it will lift from the ground this
is known as the climbing stage when
you've achieved the necessary height you
can reduce the rotor speed until the
lift force exactly balances the drone
weight
there we have it folks
levitation more technically known as
drone hovering
in both the drone takeoff and hovering
stages all the four propellers rotate at
the same speed but do you notice
anything strange about this visual
you might have spotted that one
diagonally opposite pair of propellers
rotate in one direction and the other
pair rotates in the other direction
it might look strange but if all the
propellers were spinning in the same
direction the drone body would have spun
in the opposite direction
let's see why this is the case
the stator of the motor is attached to
the drone body
the rotor of the motor turns because it
is receiving a torque from the stator
enter newton's third law of motion
if the rotor is receiving a torque from
the stator the stator will also receive
an equal amount of torque but in the
opposite direction from the rotor
if all the rotors are spinning in the
same direction the drone body will
receive reaction torque as shown
what would happen then
the net effect of these four reaction
torques would force the drone body to
turn in the same direction of the
reaction torque or in the opposite
direction of propeller rotation
by spinning the propeller pairs in the
opposite direction we are in fact making
the net reaction torque zero
interestingly the same physics is used
to achieve the yaw motion in normal
conditions all the blades will be
spinning at the same speed the yaw
motion is produced by rotating one
diagonal pair at one speed and the other
pair at a different speed
in this case the reaction torque will
not cancel out and the drone body will
spin as shown
when you control the yaw stick of the
remote control this is what happens
let's learn about the other two angular
motions of the drone pitch and roll
the pitch and roll of a drone is
controlled by the same stick
and they work based on the same physics
to pitch the drone forward the front
propellers are spun at a lower speed and
the back propellers at a higher speed
this creates a different lift force at
the front and back and thus a net torque
the net torque causes the drone to pitch
to roll the drone the same trick is
applied but to the side pairs
here one side pair is spun faster and
the other slower
once again the net torque forces the
drone to go for a roll motion
one interesting thing to note both in
the roll and pitch operation is that
even though you are changing the speed
of the propellers when you add up the
reaction torques produced by the motors
it becomes zero
this is the beauty of quadcopter drone
design they make way for stable drone
operation
the beginning of this video we saw how
to climb a drone
now let's see how the drone is flowing
forward or sideward
assume you are pitching the drone
forward after you achieve the desired
pitch angle you brought the propeller
speeds to the same value so that it
won't pitch further
the question is whether the drone can
balance here at this tilted angle
the answer is no to balance the drone we
have to first balance the gravitational
force suppose the propeller speed is
such a way that the vertical component
of the propeller force balances the
weight
here comes the issue the propeller force
has a horizontal component as well even
though the vertical forces are balanced
the unbalanced horizontal force will
move the drone horizontally this will
cause a drag force on the drone's body
the drone will increase its speed
horizontally until the drag force
matches the horizontal force
in short to fly the drone forward you
just pitch down the drone and balance it
vertically
the drone does the rest automatically
moving forward
to get the side motion the same physics
is used roll the drone towards one side
and balance it vertically
so here's a question for you is it
possible to move the drone in a perfect
circle
the secret lies in the physics of
circular motion let's shake off the dust
and brush up on our basic principles
consider an object moving in a straight
line when acted on by a force that is
always perpendicular to its velocity the
object will turn in a circle
now you have the answer in your mind for
example you can make the drone move
straight by pitching it down
now if you roll the drone as well you
can easily produce a force perpendicular
to the drone velocity
this will make the drone turn in a
circle
if you've enjoyed learning about the
interesting flight dynamics of the
quadcopter drone why not check out the
other videos in our drone series
don't forget to be one of our supporters
see you next time at learn engineering
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