Figure 26
The drone has a central circular body with four curved arms extending outward, each ending in a short cylindrical motor housing with a horizontal rotor blade on top. A cylindrical payload unit is mounted vertically above the center of the drone on a slim support. Several thin rods and cables connect the central body to the upper cylindrical unit. In the left photograph labeled “(a)”, the drone rests on low landing supports on short grass, viewed from a slightly elevated front angle, with the horizon line and tree line in the distance. In the right photograph labeled “(b)”, the same drone is captured in mid air above the grassy field, viewed from the side against a backdrop of sloping hills and open sky, with the rotor blades appearing blurred in motion.(a) The whole system before the simulation and (b) drone during take-off phase