VTOL is a term which used for unmanned air vehicles. It stands for vertical take-off and landing. There are two fundamental structure in unmanned air vehicles which are rotary wing and fixed wing. However, because of the requirement fixed wing vehicles with VTOL capacity added as a third structure. The main aim of developing this technology is combining the easiness of take-off and landing in rotary wing unmanned air vehicles and ability to stay in the air for a long time in fixed wing unmanned air vehicles.
As we all know, rotary wing unmanned air vehicles can vertically take off and start to fly without a runway. But flight durations and carrying capacities are limited according to the fixed wing unmanned air vehicles. On the other hand, fixed wing unmanned air vehicles have a complex structure regarding take-off and landing. But they can stay longer in the air. All these advantages and disadvantages taking into consideration and VTOL type fixed wing unmanned air vehicles designed for easy take-off and landing and ability to stay in the air for a long time.
Unmanned air vehicles that have VTOL ability are designed as two fundamental structure. First one is those installed with 4 fixed bearing motors positioned on arms parallel to the body except the main thrust motor. Second, thanks to the tilt relay system, horizontal and vertical torque is created by changing the direction of the main thrust Motors. Although tilt-rotor structures are more complex, they are lighter due to the use of less motor, driver, and battery. Because of these advantages, they can stay in the air longer than their counterparts.
Brushless DC motor is mostly used in rotary wing unmanned air vehicles. Internal-combustion motors are used in fixed wing unmanned air vehicles. Therefore, flight time increased distinctly. In VTOL type fixed wing unmanned air vehicles, brushless DC motor is used for take-off. Brushless DC or internal combustion engines are used for the propulsion motor that provides movement in the horizontal axis.
Unmanned air vehicles are used for search and rescue, forest fire, security of petroleum pipelines and so on. Since smooth ground conditions can easily be found in these areas, long-term observations can be made with fixed wing vehicles. In the defense industry, fixed wing unmanned air vehicles with VTOL capability are required for long-term observations in rough terrain.
