*8.1.1 Parasite drag calculation*

(**Table 7**)

#### *8.1.2 Drag polar*

Because it can be used to determine other performance metrics, the drag polar is important in characterizing and designing a UAV. Eq. (2) describes one form of the drag polar, which is based on the assumption that the least drag occurs at zero lift (**Figure 11**).


#### **Table 7.**

*Parameters for parasite drag calculation.*

**Figure 11.** *Drag polar.*

#### **8.2 Thrust modeling**

*8.2.1 Performance analysis*

## (**Figure 12**)

#### *8.2.1.1 Field performance*

Because the UAV is a VTOL, there is no need for a ground roll, but the take-off and landing can be evaluated based on the vertical height gained during take-off and

*Unmanned Aerial Vehicle for Agriculture Surveillance DOI: http://dx.doi.org/10.5772/intechopen.104476*

**Figure 12.** *Thrust modeling graphs.*

landing. The equation below was calculated using Newton's equation of motion (**Figure 13**),

$$Z = \left(\frac{T\cos\theta - mg}{2m}\right)t^2 - V\_{x\_0}t$$

where Z is the vertical distance, T is the thrust, m is the mass and *Vz*<sup>0</sup> is the stall velocity (**Figure 13**).

The maximum take-off obstacle height was found to be 293 m, while the maximum landing obstacle height was found to be 187 m, for various throttle settings with a time constraint of 10s.

**Figure 13.** *Take-off performance (left) and landing performance (right).*

#### *8.2.2 Transition phase*

#### (**Figure 14**)

*8.2.3 Climb performance*

$$ROC = \frac{Power\_{required} - Power\_{available}}{Weight}$$

where *Poweravailable* is calculated by multiplying the battery efficiency by battery current hour and the voltage that is 0.85 by 48AmpH by 12 respectively. The *Powerrequired* is the required power for climbing which can be determined by multiplying thrust require by velocity. Thus, from the graph, the optimum rate of climb is 12.58 m/s and the climb speed is 15.08 m/s. **Figure 15** shows the climb performance graphs.

**Figure 14.** *Simulink model and the transition parameters all against time.*

**Figure 15.** *Climb performance.*

*Unmanned Aerial Vehicle for Agriculture Surveillance DOI: http://dx.doi.org/10.5772/intechopen.104476*

**Figure 16.** *Thrust against velocity.*

#### *8.2.4 Cruise performance*

The cruise performance of the design is shown in **Figure 16**. Frome the graph the cruise speed is the at the minimum thrust that is 18.06 m/s.

#### *8.2.5 Range and endurance*

The maximum endurance can be determined by:

$$E = \frac{\eta\_{\text{batt}} \times volt \times Ah}{\frac{1}{2} \rho \mathbf{S}\_w \mathbf{C}\_{d0} V^3 + \frac{2K W^2}{V}}$$

that is E = 1.487 h. Range can be calculated by multiplying endurance with velocity which give 96.7 km.

#### *8.2.6 VN diagram*

The applied loads during the UAV's operational life flight and ground conditions must be known in order to create the final configuration. The load factor diagram depicts these three restrictions, with each point representing the load condition of the UAV when maneuvering at the true airspeed UAV data required to construct the load factor diagram. The safety flight conditions are provided within the limitations of the load factor diagram. Wind gusts are ascending air motions perpendicular to the ground that affect the angle of incidence and relative speed of the aircraft. Gust loads can be thought of as an increase in the load factor, necessitating the creation of a new safety field. **Figure 17** shows the wind gust load and load factor diagrams. The entire flight envelope diagram is created by superimposing the maneuverings and wind gust diagrams and is used to define the appropriate field in which the UAV can design the building.

**Figure 17.** *VN diagram and flight envelop velocities.*

#### *8.2.7 SEP chart*

The SEP chart was used to determine the design's maximum sustained turning performance for various altitudes and load factors. The SEP lines within the SEP envelope are all positive, indicating that the UAV has extra energy to do maneuvers, climb, or avoid collisions (in most cases). However, this is more power than the mission requires. Thus, boosting efficiency by employing a smaller motor and reducing battery weight while increasing endurance and preserving SEP values would be an improvement in future development. The aircraft can climb at speeds of up to 7000 feet per minute and beyond, well beyond the needed design value (**Figure 18**).

#### **8.3 Stability analysis**

It is ideal for the Cg position to be at 20–30 percent MAC because this reduces the required elevator deflection in the most operating range of speeds (cruise). 15 degrees is the elevator angle that is practical to trim during transition because the tail will deflect to trim the aircraft for the UAV to be stable, according to the graph (**Figure 19**) (**Table 8**).

**Figure 18.** *Maximum and minimum SEP (right) and SEP chart (left).*

*Unmanned Aerial Vehicle for Agriculture Surveillance DOI: http://dx.doi.org/10.5772/intechopen.104476*
