How Does a Drone Fly?
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How Does a Drone Fly?

September 6, 2019


Have you ever wondered how a quadcopter drone flies? No? Well, that was a short video then wasn’t it? I’m going to assume that either you have wondered, and for some inexplicable reason don’t want to admit it, or that the knowledge if you had it wouldn’t do you any harm. To start with I’m going to quickly cover the basic principles of flight because anything that uses a wing, or a rotor blade, or a propeller, is governed by the same set of principles. Let’s start with a wing, which is essentially what rotor blades are. A wing creates lift in two ways- firstly, due to their shape, as a wing moves through the air, the air travelling over the top of the wing moves faster than the air travelling below it. The difference in speed reduces the air pressure above the wing resulting in a certain amount of lift. This lift is added to by the angle of attack, or tilt, of the wing. The wing pushes the air below it down forcing the aircraft up. Balance the speed of the aircraft, the
angle of attack of the wing, and the drag of the air, and the aircraft will fly at a constant height. The rotor on a quadcopter or helicopter works in the same way as the wing on the plane, but rather than being pushed or pulled
through the air in a straight line like an aeroplane a rotor is made up of blades, essentially wings that are spun from their ends around a central point. The same principles apply. The air pressure above the blade is reduced and the angle of attack pushes down the air below and creates thrust which produces lift. With a helicopter you can change the angle of attack of the blades to increase or decrease the lift created. You can also tilt the rotor to achieve
directional flight forwards, backwards, left and right. The rotor blades on a quadcopter are fixed, and any difference in lift has to be achieved through changing the speed of rotation. A quadcopter like this one has four sets
of rotors, each powered by an electric motor. If you want the drone to go up you
apply more power to the rotors and if you want it to come down you apply less. Want to go forward, simply apply more power to the two rear motors. The drone will tip forward and fly forward because the thrust is now being pointed backwards as well as downwards. This forward and backward tilting movement is called pitch. Feel the urge to go left? Apply more power to the right-hand
rotors. The right-hand side of the drone lifts pointing the thrust out to the right and the drone moves to the left. The opposite is also true if you want to
go right. This side-to-side tilting movement is called roll. The rotors come in diagonally opposite pairs. One pair rotates in one direction, and the other pair rotates in the other direction. If they weren’t set up like this all the
torque, or the force of rotation, would be pushing in the same direction and the drone would simply spin. With the opposing configuration the torque from one pair of rotors pushes in the opposite direction to the other which cancels out, and the drone doesn’t spin. A useful side effect of this means that by
increasing the power to one set of rotors and reducing the power to the
other you can turn the drone. This turning movement is called your Yaw. Now all of this is of course really clever and theoretically quite simple, but without a bit of computer jiggery-pokery it would be very hard to control your drone. By allowing a computer to make all the necessary adjustments, at a speed far faster than we can cope with, and feeding in a host of data from inputs like GPS, a compass, a barometer, ultrasonic sensors, and cameras, a drone can practically fly itself, and that’s just about what it does. It’s doing the flying, and you are
making suggestions about where it should go. Now I hope that all this makes sense. I have tried to be concise and not get bogged down in the minutia. And now, for your viewing pleasure, a bit of drone footage. Feel free to like, subscribe, share, and comment, and we’ll be back with another video tomorrow. Music

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  1. Very nicely done. I know more than half of the drone pilots out there have no clue as to how their drone flies. Maybe now they do. And yes, of the hundreds of Youtube videos I have watched since getting my Mavic, never have I watched one like this one! Enjoyed.

  2. wow thank you for explaining i would definitely like to build a drone myself this is my favorite video i have ever watched

  3. Ian, did you ever used to be an air cadet? I was a Civilian Instructor and this is just like what I used to teach the cadets lol Good job πŸ™‚

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