Principals of quadrocopters

As I promised a few days ago, today I try to explain what do we want to build, how it works (and flies :) ) and what do we want to achieve eventually.

What a quadrocopter is?

Quadrotors, also called quadrocopters are multicopters, which are lifted and propelled by using four rotors. Basically, it consist of four motors with propellers and a kind of electronics which control stability during the flight. All of those parts are attached to frame, which has shape of ‘X’ or ‘+’. Quadrocopter in many cases is steering by some radio controller – it means that it could be classified as an UAV (Unmanned aerial vehicle) or drone. Nowadays, the popularity of quadrotors increased, especially among model-makers, because of chip equipment necessary to build it. Let’s take a look how it works.

Why quadrotor flights?

Quadrocopter needs for construction a frame, propellers and electric motors. To obtain the best performance and a simplest control, motors and propellers should be placed at the same distance between them [pictures on a left side]. The frame should be strength, tough, but also have light weight. Due to this factors, carbon composites seems to be the best choice. 

Electrical motors must be powered and controlled :). So, quadrotor to flight need some electrical components. They are ESC (Electronic Speed Control) modules, which are responsible for powering a single motor, and controlling. Depends on a type of motor, it could need different control. In a future I will describe what type of motors and ESCs we will use.








As it was mentioned earlier, quadrocopter consist mainly of four motors with propellers. Each of them produces both a thrust and torque about center of rotation, and also a drag force, which has got opposite to vehicle’s direction of flight. We have to use four propellers: two pairs of counter rotating props (two rotates clockwise, and two rotates counterclockwise, on the opposite arms of frame). If all of them rotates with the same angular velocity, the vehicle will move up and down. If controller wants to change the direction of flight, one of motor must increase its RPM (revolutions per minute), and the opposite motor have to decrease its RPMs. It is adjusting its pitch and roll forces Also, vehicle could adjust its yaw by applying more trust to rotors rotating in the same direction. In this case, quadrocopter would rotate around his center of rotation. The pictures will describe it more briefly:

At the end of this post, some motivation for us and you :) maybe our vehicle will never acts as in those movies, but we will be happy and satisfied if it fly and works properly :) More videos on http://www.flyingmachinearena.org/videos/

References:

[1] http://www.rchelicopterfun.com/quadrocopter.html
[2] http://wyvernupenn.blogspot.ca/2010/04/mechanical-design.html
[3] http://cog.yonsei.ac.kr/quad/quad.htm
[4] http://oddcopter.com/2012/12/12/easy-diy-quadcopter-build-part-1-the-parts-list/
[5] http://oddcopter.com/2012/12/19/easy-diy-quadcopter-build-part-2-the-build/
[6] http://www.slideshare.net/lenntilley/quadrocopter-build-manual
[7] http://www.slideshare.net/LenzGr/how-to-build-your-own-quadrocopter