Unmanned Aerial Vehicle Research Paper

Unmanned Aerial Vehicles (UAVs) are used in many applications such as search and rescue, surveillance, or responders in a natural disaster. UAVs are now very important for armed forces and rescuers. In particular, UAVs are useful in applications like coastal surveillance, hurricane watch, and traffic control. UAVs show great potential for many other applications like precision agriculture, package delivery, wind turbine maintenance etc. Small UAVs can carry limited energy on board. Since having small size and low flying speeds, UAVs operate at low Reynolds number (Re: ratio of inertial forces to viscous forces.) At low Re, the aerodynamic performance of a small UAV becomes much worse than its large counterpart, since viscous forces come

The vertical component of the wind offsets the sink rate of the bird or aircraft, which can be obtained easily from the wind blowing up a slope. Many bird species are observed to use this slope soaring in proximity to ridges and cliffs [9]. RC pilots also make use of this slope soaring frequently. Collectively, thermal soaring and slope soaring come under the category static soaring, as steady vertical component of the wind is used in obtaining the energy. Energy extraction from high frequency turbulence in the atmosphere is known as gust soaring [11]. In the gust soaring, energy is extracted from gusts by increasing lift in regions of updrafts and decreasing it in regions of downdrafts, while maintaining average lift similar to the vehicle weight. It is difficult to extract enough power from gusts, unless high levels of turbulence are

1.1. When a component of the aerodynamic force on the vehicle is aligned with the local wind vector, energy is extraction from the atmosphere takes place. Consider a section of the trajectory marked '1'. At that section the lift vector has a component along the wind speed vector, which is also of large magnitude, indicating the gain of significant energy. Along section '2', the directions of lift vector and the wind vector are nearly opposite, indicating a loss of total energy due to the winds. However, this loss is smaller in amount than that gained at altitude because of the wind gradient. If there is balance between the integrated energy gained from the wind along the trajectory and the energy lost due to drag, then a neutral energy cycle is possible and without expending energy for propulsion the bird or aircraft can fly