Quadcopter / August 10, 2018 / Sanni Pekkarinen.
UAV stands for Unmanned Aerial Vehicle and it covers all remotely controlled machines that are also known as quadcopters as well as aircraft used by the US air force. These machines are mainly used by military and police officers to carry out an operation where a manned aircraft seems impractical or too risky. Unmanned aircraft are not new; they have been in use since the World War I. However at that time the control was mechanical and the aircraft could only go as far as the fuel would allow. Later on devices that could be controlled with the help of radio or infra-red technology were developed. These devices became the predecessors of the modern quadcopter that employs integrated circuit or computer chips and can be programmed to fly for a definite time period in a definite direction fulfilling a definite purpose.
You may have seen some pretty amazing flying vehicles these days. UAVs (unmanned aerial vehicles) are becoming more and more common. The hobby is also getting more and more easy to get into. But with the great range of models and brands you may wonder what is the best quadcopter to start out with. There are a several variations of the multirotor family. The most common is the quadcopter like the DJI Phantom. A quadcopter uses four motors and propellers to generate the thrust necessary to lift the aircraft. It can be more mechanically simple than a traditional helicopter that requires a tail rotor to counteract the angular torque produced by the main rotor and the main rotor does not require collective pitch and other mechanical complexities. With a quadcopter the pitch is fixed and the flight control is achieved by actively changing the motor RPM (revolutions per second).
If the Kv of the motors is too low you may need to increase the number of series cells in your battery pack. That is what happened in my saucer quadcopter. Three cells in series were not enough to provide the power I wanted. When I switched to a 4S battery pack it came alive. This is also a highly demanding application with constant high current flows. I needed a quality battery with at least a 30C rating. If you lose power while flying a quadrotor you are dead. It is not like an airplane where you can glide to a safe landing. With a quad you need to keep a close watch on the flying time and land long before the battery runs out. Dont try and beat a flying duration record! A low battery on-board alarm might be a wise investment too.
In order to take off you only need to push the throttle up but make sure you do it very slowly till the copter lifts off. Push it back to zero to see how the machine will land once the flight is over. Remember this is the most important step so master it by repeating it many times and then checking if the copter tries to move on its own. If you are not pushing any control and the machine is still rotating rolling or moving you need to use the trim buttons to balance it out. Without doing this step you wont be able to get a smooth flight so dont overlook its importance. To hover in mid-air you will need to experiment a little with the controls. When you decide your flight is over and the machine now needs to land slowly start cutting back the throttle. Remember there is nobody aboard the copter so even if it drops to the ground its perfectly all right. Just make sure you push the throttle suddenly to zero only when the machine is only an inch or two up from the ground.