The design of UAV for patrolling flammable areas of the forest

Abstract

The paper is devoted to the description of monitoring forest fires using unmanned aerial vehicles (UAV). The article discusses and analyzes a way of monitoring forest fires using UAVs. Different types of UAVs and their usage in fighting forest fires were considered. The effectiveness of applying tiltrotor with vertical take-off and landing (VTOL) scheme is mentioned. The advantages of using UAVs for monitoring forest fires are revealed.

Full Text

Forest fires are a huge problem nowadays. The spontaneous spread of fire across the forest area entails damage to the environment, the economy and, which often happens, endangers human lives. For countries where forests cover a large area, forest fires are a national problem.

For example, in 2022, the scale of wildfires in Russia became catastrophic ahead of schedule. The Russian branch of Greenpeace said that in the first four months, the area of devastating fires was twice as large as in the same period in 2021.

Timely detection of forest fires prevents their further spread. The detection of forest fires involves many preparatory operations, including aerial patrols. The aerial method of detecting fires in forest areas has more possibilities, but, due to economic and organizational reasons that emerged in the 1970-80s, the cost of flying has increased by 3 times, and the number of aerial vehicles had fallen by 5 times. This led to the failure to meet the standards for the frequency of aerial patrols, and in addition to this - to episodic patrols, which has its own consequences.

Given the lack of funds for air patrols by such aircrafts, the role of the suing or creating new aircrafts had begun to grow. Different types of other aerial vehicles exist for these purposes as well, but it should be noted that unmanned aerial vehicles (UAVs) are a good alternative to the aircrafts used in the past.

An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without any humans on board. Besides, drones are effective means of acquiring different information from the air.

There are more advantages in using drones to perform patrols of the forest:

• Quality of aerial photography. Thanks to high-resolution cameras with powerful sensors, drones can take excellent aerial photos and accumulate large amounts of accurate data and a possibility of installing machine vision for automatic detection of smokes and fires in forest areas;
• Cost-saving technology. This is primarily because drones are capable of replacing aircrafts, which need fuel and costly storage and maintenance;
• Minimization of health risks. Unmanned aerial vehicles (UAVs) provide easy and safe inspection of any territories.

The aim of this work is to choose a method for improving fire safety of forests using UAVs, specifically – designing a drone to perform patrols of forest areas with the most efficient parameters possible.

What type of a UAV will be used?

There are two types of aerial vehicles now: aircrafts, such as planes, and helicopters.

The aircraft-type UAV differs from other types of drones with its greater duration and range of flight at higher speeds. These characteristics allow aircraft-type UAVs to be used when the vehicle needs to stay in the air for a long time to achieve the longest route. But, performing a detailed scanning of forest territories with high efficiency is uncomfortable, because it is almost impossible to maneuver between the trees. Helicopter- and multirotor-type aircraft are in the air due to the constant rotation of one or more lifting rotors. The flight of this type of UAV requires a constant expenditure of energy. This considerably reduces the duration and range of the flight. In return, this drone offers the greater maneuverability needed to fly around an object or any territory more accurate.

After analyzing the available solutions, we propose to combine the advantages of aircraft and helicopter types and develop a tiltrotor based on VTOL system. To be more exact, a tiltrotor is an aircraft with four engines, which generates lift and propulsion with these rotors, mounted on rotating shafts at the ends of a fixed wing. A tiltrotor aircraft differs from a tiltwing in that only the rotor pivots rather than the entire wing. The advantages of the VTOL tiltrotor with three engines over an ordinary tiltrotor is higher stability during takeoff and landing saving electrical energy, since a conventional tiltrotor has four engines and consumes more energy. During our research, we concluded that a drone for patrolling forest areas does not need a large payload and dimensions, but we do need to save energy in order to have an ability to fly over a larger area of the forest.

Tiltrotor design combines the VTOL capability of a helicopter with the speed and range of a conventional fixed-wing aircraft. For vertical flight, the rotors are angled so the plane of rotation is horizontal, generating lift the way a normal helicopter rotor does. As the aircraft gains speed, the rotors are tilted forward, with the plane of rotation eventually becoming vertical. In this mode the rotors provide thrust as a propeller, and the airfoil of the fixed wings takes over providing the lift via the forward motion of the entire aircraft. Using this system will allow us to perform project’s goals.

From the whole family of tiltrotors, the most optimal option for our project’s needs is a tiltrotor with three engines and propellers (Figure 1). Two of them are front motors mounted on servos and a rear supporting one, for vertical take-off, landing and balancing in the air.

The complexity of the scheme lies in the organization of control in the modes of vertical and horizontal flights, as well as transitional ones - it is difficult for the pilot to navigate, because same controls perform different functions in different modes. In addition, visibility is obstructed in vertical modes, but it can be fixed by installation of a camera with 360 degrees rotation mechanism.

What are the characteristics of our tiltrotor?

In order for our tiltrotor to perform the goals set by our project’s needs, its component layout needs to be made up according to the maximum efficiency, as told in the aim of our work. It is important to make our UAV’s weight as light as possible to save on energy costs and flight duration of the vehicle in different flight modes.

By entering our hull’s parameters such as wing span, root chord, tip chord and sweep, we calculated the wing area of our tiltrotor, which is 225875 mm². This wing area is shown on Figure 2. Its sizes allow us to generate enough lift and do not let our tiltrotor fall in the air.

The creation of our tiltrotor’s component layout and its final parameters are presented in the Figure 3. They were made in the eCalc calculator. It should be noted that they show our helicopter’s mode only, since aircraft mode’s parameters and ways of calculating them will differ from helicopter mode. This layout and some other characteristics that are not mentioned in the Table 1 are shown on Figure 3. Besides, it tells us how effective all of those listed components when combined are.

Table shows the characteristics and component layout of our tiltrotor. Trying out other combinations of components layout could give us better results, however, we would gain more flight weight with large payload and dimensions as well, which we don’t need for our project’s goal.

Conclusion

As a result of this work, we have analyzed almost all possible ways of patrolling forest fires were overlooked and discussed. In addition, during our research, we have concluded that the usage of a UAV with VTOL scheme is the best option for aerial patrols of forest areas due to its properties of both aircraft and helicopter types of vehicles.

Some parameters of our UAV might be changed in the future in order to improve the general efficiency of the tiltrotor. The project is currently on a designing stage, but it is planned to create an operational prototype based on all of those characteristics listed above in the next year.