Development Stages of Quadrotors from Past to Present: A Review

Highlights

What are the main findings?

• The leading manned quadrotors, from their initial invention in the early 1900s to the present day, are reviewed in detail, along with their industrial development processes, technical specifications, photographs, and areas of use. Information is provided on manned quadrotors that remained in the prototype phase due to accidents, budget constraints, or failure to meet military standards, and the future development of manned quadrotors is discussed.
• The historical development of quadrotor unmanned aerial vehicles (UAVs) from the late 1990s to the present and their increasingly widespread use are discussed. The technical specifications, development processes, areas of use, and photographs of the mass-produced and widely used quadrotor UAV models are comprehensively described. The evolving features of quadrotor UAVs and their future uses are discussed.

What are the implications of the main findings?

• This review article addresses a significant gap in the literature by providing a detailed overview of the development of manned quadrotors from their initial invention to the present. Unlike studies that focus solely on the recent past, the development of manned quadrotors is examined chronologically and explored as a future direction, providing researchers with a holistic and meaningful perspective.
• This review article highlights the development of landmark quadrotor UAVs from the 1990s to the present, highlighting key milestones. This article describes the first quadrotor UAV models to enter mass production, the first to be equipped with cameras, the first to be used in search and rescue operations, and the first to be able to track their operators. It also explains how the increasing features and evolving capabilities of quadrotor UAVs will impact their future use. Unlike review articles that focus solely on quadrotor UAVs from the last 10–15 years or on quadrotors specialized in a single field of use, this article offers a much more comprehensive perspective.

Abstract

Quadrotors have been under development for over a century. The first quadrotors were large, heavy, and difficult to control aircraft operated by a single pilot. The first quadrotors remained in the prototype stage due to accidents, budget cuts, and failure to meet military standards. Production of manned quadrotors ceased in the 1980s. Since the 2010s, manned quadrotors have been used as air taxis, achieving greater success. The development of quadrotor unmanned aerial vehicles (UAVs) began in the 1990s. Their small size, low cost, and ease of control have made them advantageous. Advances in hardware and software technologies have expanded the use of quadrotor UAVs. Today, quadrotor UAVs are used in various fields, including surveillance, aerial photography, search and rescue, firefighting, first aid, cargo transportation, agricultural spraying, mapping, mineral exploration, and counterterrorism. This review examines the development of manned quadrotors and quadrotor UAVs in detail from the past to the present. First, the major manned quadrotors developed are described in detail, along with their technical specifications and photographs. Graphs are provided showing the weight, powerplant, flight duration, and passenger capacity of manned quadrotors. Second, the main quadrotor UAV models entering mass production are discussed, presenting their development processes, technical specifications, areas of use, and photographs. Graphs are presented showing the weight, battery capacity, flight duration, and camera resolution of quadrotor UAVs. Unlike studies focusing solely on the recent past, this review provides a broad overview of the development of quadrotors from their inception to the present.

1. Introduction

A quadrotor is an aircraft capable of vertical takeoff and landing [1]. It is a type of multicopter equipped with four rotors [2]. Typically, two rotors rotate clockwise, while the other two rotate counterclockwise [3,4]. Flight control is achieved by independently varying the speed and torque of each rotor [5]. The pitch and roll motion of the quadrotor is controlled by changing the net center of thrust, while the yaw motion is controlled by changing the net torque [6].

The first quadrotors began to be produced by scientists in the early 1900s [7]. These were manned aircraft operated by a pilot. The first quadrotors were quite large, heavy, and cumbersome. They consumed high fuel and had limited ground clearance. Their range was short [8]. In the years following World War II, more advanced manned quadrotor prototypes were produced. However, they experienced stability issues, placing a significant burden on the pilot. Furthermore, high costs and some accidents involving manned quadrotors have prevented the mass production of prototypes [9].

From the 1990s onward, quadrotor unmanned aerial vehicles (UAVs) began to develop [10]. Advances in battery, sensor, software, and hardware technologies have accelerated and simplified the production of quadrotor unmanned aerial vehicles [11]. Quadrotor unmanned aerial vehicles are much smaller and have a much lower production cost compared to manned quadrotors [12]. Quadrotor unmanned aerial vehicles can be remotely controlled [13]. Advancing technology also allows quadrotor unmanned aerial vehicles to be controlled via apps installed on mobile phones [14]. Furthermore, many quadrotor UAVs are capable of autonomous flight [15,16]. Some of the modern quadrotor UAVs have the ability to track the face of the person controlling them remotely [17,18]. Small quadrotors that can fly within a room and take off and land in the palm of a hand have become widespread today [19].

Technological advances have led to an increase in the usage areas of quadrotors. Quadrotors equipped with cameras can be used in areas such as surveillance, hobby photography, and search and rescue operations [20]. Quadrotors equipped with thermal cameras can detect the body temperature of living creatures, making search operations easier [21]. Additionally, camera-equipped quadrotors are used by scientists to observe wildlife and by journalists for reporting [22,23]. They are also used by security forces for border control and patrols [24,25,26].

Quadrotors that can carry payloads can be used for first aid [27]. Quadrotors are also used for organ transport between hospitals for transplants [28,29,30,31,32]. Medical quadrotors are also used in operations to transport blood bags and red blood cells [33,34,35]. Thanks to image processing and neural network technologies, quadrotors can detect fires and support firefighting efforts with the payload they carry [36,37,38,39,40,41]. Payload-carrying quadrotors are also used by cargo companies for cargo delivery [42,43,44,45,46]. Thanks to advanced image processing technologies, cargo drones can deliver cargo to the recipient’s lap or in front of their home [47,48]. Quadrotor UAVs carrying payloads are also widely used in agricultural spraying [49]. Using image processing technologies, they can detect pests on plants. This allows for more accurate and efficient spraying and reduces costs [50,51]. Quadrotor UAVs are also widely used in mineral exploration thanks to their advanced image processing technologies and metal detectors [52,53,54]. Quadrotor drones, which carry weapons and ammunition, can be used by security forces against terrorist organizations. These quadrotor drones can track terrorist vehicles, lock on to them, and destroy them [55,56,57]. Furthermore, with their advanced cameras and image processing methods, quadrotor UAVs are widely used in mapping today [58].

Researchers have written a significant number of review articles on quadrotors. However, most of these review articles focus on quadrotor UAVs within the last 20 years. Therefore, the historical development of quadrotors from the past to the present cannot be fully covered. Idrissi et al. reviewed the development of quadrotor UAVs over the last 18 years. They examined different quadrotor UAV configurations, their mechanical structures, and explained their dynamics. They also addressed simulation tools and control strategies related to quadrotor UAVs [59]. Sonugur examined the controller designs and simultaneous localization and mapping (SLAM) methods used in quadrotor UAVs over the last 20 years. He categorized the controller designs he examined into three categories: linear, nonlinear, and intelligent control. He compared the performance metrics of different quadrotors in both controller design and SLAM, and presented the results in tables [60]. Khalid et al. compared the performance of different control strategies by examining quadrotor UAVs developed over the last 10 years. Their analysis revealed that hybrid control strategies produce improved results compared to conventional control methods [61]. de Oliveira Evald et al. examined quadrotor UAVs developed over the last 20 years and discussed their attitude control techniques. They categorized attitude controllers into five distinct categories: sliding-mode controllers, higher-order sliding-mode controllers, observer-based controllers, robust controllers, and miscellaneous controllers [62]. Abro et al. focused on quadrotor unmanned aerial vehicles, which have been developed since the 1990s. They discussed different control strategies for quadrotor UAVs. They addressed PD, PID, MPC, SMC, and reinforcement learning-based control techniques. They also briefly touched on current topics such as autonomous flight, human–UAV interaction, and swarm UAVs [63].

Some reviews focused on quadrotor UAVs operating in a single domain. Shaipul et al. have written a review article examining payload quadrotor UAVs. They discuss the sectors in which payload quadrotor UAVs can be used, how to upgrade their algorithms, and how to increase their energy efficiency [64]. Chen et al. wrote a review article on aerial spraying with unmanned aerial vehicles. In their study, they compared the aerial spraying performance of a quadrotor, a hexarotor, and a twin-rotor UAV. They compared the effective wind field and average wind pressure of these UAVs [65]. Dang et al. wrote a review article on quadrotor UAVs used in mineral exploration. They categorized mines into different categories, such as surface mines, underground mines, and abandoned mines. They explained the type of UAV that should be used for each category [66]. Ramachandran et al. studied object detection with unmanned aerial vehicles. They classified unmanned aerial vehicles based on their rotor counts as quadrotors, hexarotors, tricopters, and octocopters. Objects in videos captured by these drones’ cameras were detected using different object detection algorithms. The authors compared the advantages and disadvantages of these algorithms [67]. Shen et al. wrote a review article on the development of hydrogen fuel cell multi-rotor drones. High energy density, strong adaptability to ambient temperatures, and no pollution emissions are presented as advantages of hydrogen fuel cells. Compressed gaseous hydrogen storage methods, liquid hydrogen storage methods, and solid-state hydrogen storage methods are discussed in detail [68]. Sabour et al. categorize UAVs into six categories based on their intended use: Reconnaissance, Combat, Logistics, Research and Development, Civil and Commercial Applications, and Target and Decoy. They also provide a percentage breakdown of various studies conducted on multi-rotors. Their study focused on the classification and usage areas of UAVs but did not provide information on UAV models or their technical specifications [69]. Subramaniam et al. analyzed studies examining the aerodynamic performance of various multirotors, such as quadcopters, hexacopters, and octocopters [70]. Saif et al. wrote a review article examining hybrid power systems developed for multirotor UAVs over the last 20 years [71]. Throneberry et al. reviewed studies on wake propagation and flow development in multirotor UAVs. The authors examined ground, ceiling, and wall effects within the scope of proximity effects studies. They analyzed hovering flight, forward flight, and vertical flight within the scope of Computational Fluid Dynamics (CFD) [72].

Table 1. Summary of quadrotor review articles.

Main Focus	Total Reviewed Examples	Years Cov.	Ref.
Architectures and control algorithms of UAVs	9 UAV architectures and 9 control strategies	2003–2021	[59]
Control and SLAM technologies	11 control, 9 SLAM methods	1995–2022	[60]
Quadrotor UAV control schemes	16 control schemes	1998–2023	[61]
Quadrotor UAV attitude controllers	5 control types	2006–2023	[62]
Quadrotor UAV control strategies	12 control strategies	1994–2023	[63]
Payload trans. with quadrotor UAVs	11 different payload designs and the effects of their implementations	2017–2023	[64]
Multirotor UAV spraying systems	4 nozzle systems	2014–2022	[65]
Quadrotor UAVs in mine industry	8 applications of UAVs in the mining industry	2015–2022	[66]
Object detection in quadrotor UAVs	11 image proc. methods	2012–2021	[67]
Hydrogen Fuel Cell technologies for quadrotor UAVs	3 hydrogen storage methods	2015–2023	[68]
Applications and classifications of UAVs	6 functional categories of UAVs	2008–2021	[69]
Analysis of the aerodynamic performance of multicopters	3 different multicopter types	2007–2023	[70]
Hybrid power systems for multirotor UAVs	The technical data of 13 hybrid engines	2001–2021	[71]
wake propagation and flow development in multirotor UAVs	Three proximity effects and three types of wake propagation	2005–2021	[72]

provides a summary of review articles on quadrotors, including the main focus of the articles, the number of examples covered, the years covered, and the reference number of the study.

This study examines in detail the development of quadrotors from their initial invention to the present. This review article examines industrial studies on quadrotors, the technical specifications, production purposes, areas of use, and photographs of landmark quadrotors.

The contributions of this review article can be summarized as follows: Many review articles on quadrotors focus solely on quadrotor UAVs developed in the last 10–20 years. They neglect the historical development of quadrotors and manned quadrotors. This study provides a detailed overview of the development of quadrotors from their initial invention to the present. It examines not only quadrotor UAVs but also both the earliest and current manned quadrotors.

Many review articles on quadrotors mainly focus on the classification of quadrotor UAVs and the control strategies developed for quadrotor UAVs, but their technical specifications are often overlooked. This review article presents in detail the technical specifications of both manned and unmanned quadrotors. The technical specifications of a total of 10 manned quadrotors are presented in tables. Graphs are provided for their weight, powerplant, flight duration, and passenger capacity. The technical specifications of a total of 30 quadrotor UAVs are presented in tables. Graphs are provided for the weight, battery capacity, flight duration, and camera resolution of these quadrotor UAVs.

Some review articles compare quadrotors specialized in a specific area (e.g., payload transport, agricultural spraying, mineral exploration, object detection) with other drones that perform the same function (trirotors, hexarotors, etc.). This review article, instead of focusing on quadrotors specialized in a single area, broadens the scope and addresses all areas of application for quadrotors.

The second section describes the methodology employed in this review. The third section explores the development of manned quadrotors. The technical specifications, production processes, and application areas of these quadrotors are explained. The fourth section discusses quadrotor unmanned aerial vehicles. The operating principles and application areas of quadrotor UAVs are explained. The technical specifications of landmark quadrotor UAVs are reviewed. Section 5 describes the future directions of manned quadrotors and quadrotor UAVs. Section 6 presents the conclusions of this review article.

2. Methodology

This section outlines the methodology used in this review article. This section describes source selection, inclusion criteria, exclusion criteria, data extraction, and analytical approach, respectively.

2.1. Source Selection

The primary objective of this review article is to examine the evolution of landmark quadrotors from their initial invention to the present day. Table 1 was created by reviewing important review articles on quadrotors, tabulating their main focus, the number of samples examined, and the years covered. All review articles in Table 1 date back to the last four years. This approach was followed by a review of current literature. Care was taken to select these review articles from SCI-indexed Q1, Q2, and Q3 journals. Among these journals, the journal with the lowest IF was 1.6, while the highest was 28. The average IF was 7.07. Among the SCI-indexed review articles in Table 1, the lowest cited article received 17 citations, while the highest cited article received 369 citations. The average citation value was 93.81.

The literature search for this study was conducted using primary academic databases such as Scopus, Web of Science, and Google Scholar. Keywords such as quadrotor, quadcopter, VTOL, manned quadrotor, UAV, and multirotor were used in the search process.

2.2. Inclusion Criteria

Only manned quadrotors that were manufactured as real prototypes and flight-tested, as well as quadrotor UAV models that were widely used or entered mass production between 1999 and 2025, were included in the review.

2.3. Exclusion Criteria

Models that remained in the design phase, had not flown or lacked verifiable technical data were excluded from the study. Fixed-wing vehicles were also excluded. Multicopters that are not quadcopters (tricopters, hexacopters, octocopters, etc.) were excluded as well.

2.4. Data Extraction

For each model, basic technical information such as weight, power type, battery capacity, flight duration, service ceiling, speed, camera specifications, sensor specifications and year of production was compiled.

2.5. Analytical Approach

The review article is divided into two main sections: manned quadrotors and quadrotor UAVs. First, manned quadrotors between 1907 and 2022 were examined chronologically. Then advances in quadrotor UAVs covering the period 1999–2025 were evaluated. To identify trends, the models were compiled into common tables and technical indicators were compared graphically. The obtained data were also used to discuss developments in propulsion, battery, sensors and autonomy.

The manned quadrotors section (Section 3) begins with the first manned quadrotor, Gyroplane No. 1, produced in 1907, and covers manned quadrotors produced up to 2022. This review covers manned quadrotors that have been produced at least as prototypes and have completed test flights. Manned quadrotors that remain in the design phase are not included in the review article. The historical development of manned quadrotors is described, photographs are provided, and their technical specifications are presented in tables. Table 12 lists the prominent features of manned quadrotors produced during the period in which they were produced. The weight, powerplant, flight time, and passenger capacity data for all the manned quadrotors examined are compiled into a single table, creating Table 13. Graphs are drawn based on Table 13, and the resulting data is analyzed.

The quadrotor UAV section (Section 4) covers the historical development of quadrotor UAVs. This section covers quadrotor UAVs that have entered mass production and have a significant place worldwide. This section describes quadrotor UAVs that entered mass production between 1999 and 2025. A total of 30 models from five different leading brands in quadrotor UAV production were examined. Quadrotor UAV models are used in various fields, including reconnaissance and surveillance, aerial photography, search and rescue, mapping, cargo transport, scientific research, and agricultural spraying. The development process, prominent features, intended use, photographs, and technical specifications of each quadrotor UAV model are presented. Table 45 shows the prominent features of the quadrotor UAVs discussed in the review article, based on the period in which they were produced. Table 46 provides the weight, battery capacity, flight time, and camera resolution of the quadrotor UAV models. Graphs were then created using the data in Table 46, and the results were analyzed.

3. Development Stages of the Manned Quadrotors

Historically, the first quadrotors produced were manned quadrotors controlled by a pilot. The production of the first manned quadrotors dates back to the early 20th century. This section describes manned quadrotors in detail, from their earliest production to the present day. The technical specifications of the prototypes, any accidents they were involved in, their intended use, and whether they entered mass production are discussed in detail.

In 1907, French electrical engineer Louis Charles Breguet and his brother, aeronautical engineer Jacques Breguet, along with French psychology professor Charles Richet, developed the first quadrotor, which they named the Bréguet-Richet Gyroplane No. 1. The quadrotor had a seat for the pilot and a central engine. The quadrotor had two steel arms, each constructed in two layers, extending from the center toward the four rotors. To eliminate torque, two rotors rotated clockwise, while the other two rotated counterclockwise. The quadrotor could only move vertically and required four people to maintain stability. The Bréguet-Richet Gyroplane No. 1 rose 0.6 m above the ground on its first attempt. Later improvements allowed it to reach 1.52 m above the ground. Gyroplane No. 1 made its maiden flight on August 24, 1907. A photograph of Gyroplane No. 1 taken in 1907 is shown in Figure 1. According to the photograph, the person standing on the right is Louis Charles Breguet. The technical specifications of Gyroplane No. 1 are given in

Table 2. Technical specifications of Gyroplane No. 1.

Parameter	Value
Crew capacity	1 person
Flight time	1 min
Service ceiling	0.6 m
Height	3.7 m
Empty weight	500 kg
Gross weight	578 kg
Main rotor diameter	4 × 8 m
Main rotor area	402.2 m2
Powerplant	46 hp Antoinette water-cooled piston engine

[73].

In 1908, the Bréguet-Richet Gyroplane No. 2 was produced, a further development of the existing design. This design used 7.85 m diameter propellers and fixed wings. It was powered by a 55 hp Renault engine. This second version made several successful flights in the summer of 1908 before being severely damaged during a landing on 19 September 1908. After the severe damage, it was repaired and renamed Gyroplane No. 2 bis, making one final flight before April 1909. In April 1909, a severe storm destroyed the company’s quadrotor and all its work [73]. A photograph of Gyroplane No. 2 taken in 1908 is shown in Figure 2. The technical specifications of Gyroplane No. 2 are given in

Table 3. Technical specifications of Gyroplane No. 2.

Parameter	Value
Crew capacity	1 person
Flight time	1 min
Service ceiling	3.96 m
Gross weight	550 kg
Main rotor diameter	4 × 4.3 m
Powerplant	55 hp Renault engine

[74,75].

French engineer Etienne Oehmichen, working for Peugeot, began experimenting with rotary-wing designs in the 1920s. His first designs used a 25 hp engine, but this engine failed to generate sufficient lift for takeoff. In 1922, he developed his first notable quadrotor design, the Oehmichen No. 2. It used a 120 hp Le Rhone engine and made its maiden flight on 11 November 1922. The Oehmichen No. 2 later used a 180 hp Gnome engine. The Oehmichen No. 2 had a steel frame. In 1924, the Oehmichen No. 2 broke the record for the longest-flying rotary-wing aircraft by flying 360 m. It later set a new record by flying 525 m. It then followed a triangular trajectory, flying for 7 min and 40 s and covering 1 km. For this achievement, Etienne Oehmichen was awarded 90,000 francs by the French government. In a 1924 flight, the Oehmichen No. 2 remained airborne for 14 min and covered a distance of 1.6 km. In 1924, Etienne Oehmichen successfully completed a flight with the Oehmichen No. 2, carrying two passengers. The technical specifications of the Oehmichen No. 2 are given in

Table 4. Technical specifications of Oehmichen No. 2.

Parameter	Value
Crew capacity	1 person
Passenger capacity	2 people
Flight time	14 min
Service ceiling	1 m
Empty weight	800 kg
Gross weight	1000 kg
Rotor diameter	2 × 6.5 m, 2 × 7.5 m
Powerplant	180 hp Gnome engine

[76,77,78]. A photograph of the Oehmichen No. 2 is shown in Figure 3 [78].

George de Bothezat, a nobleman and scientist of Russian origin, also conducted significant research on quadrotors. He began studying Electrical Engineering at the Kharkiv Polytechnic University in 1902. He then studied Electrical Engineering at the University of Liège in Belgium for two years between 1905 and 1907. He then returned to his homeland and graduated from the Kharkiv Polytechnic University in 1908 with a degree in Electrical Engineering. After graduating, he pursued postgraduate studies at the University of Göttingen and Humboldt University in Berlin. In 1911, he completed his doctorate in aircraft stability at the Sorbonne University. During his academic studies, he focused on winged aircraft rather than general aerodynamic theory. Following the Bolshevik Revolution in Russia in 1918, he emigrated to the United States. There, he taught at MIT and Columbia University and, in 1920, wrote one of the first articles in the scientific literature on rotary-wing unmanned aerial vehicles. At the request of the US Army, he went to Ohio State and began designing one of the first quadrotors. In December 1922, he developed the quadrotor, which he named the “de Bothezat helicopter”. On its first flight, the quadrotor climbed 1.8 m above the ground. In subsequent flights, it reached altitudes of up to 9.1 m. Able to carry a pilot and four passengers, the quadrotor’s maximum speed was determined to be 48 km/h. However, because it could only fly when it caught a favorable wind and was very difficult to control, production of the quadrotor was canceled by the US Army in 1924 [79]. A photograph of the de Bothezat quadrotor taken during a test flight in 1923 is presented in Figure 4 [80]. George de Bothezat applied for a patent for the quadrotor he developed in the USA in 1924, and his application was accepted in 1930. The technical specifications of the de Bothezat quadrotor are given in

Table 5. Technical specifications of de Bothezat quadrotor.

Parameter	Value
Crew capacity	1 person
Passenger capacity	4 people
Flight time	2 min 45 s
Service ceiling	5 m
Absolute ceiling	9.1 m
Height	3 m
Gross weight	1633 kg
Main rotor diameter	4 × 8.1 m
Main rotor area	84 m2
Powerplant	220 hp Bentley rotary engine
Maximum speed	48 km/h

[81].

The US company Convertawings examined the quadrotors developed by Oehmichen and Bothezat. Using these concepts, they developed a four-propeller concept. In 1955, they produced and successfully flew the first prototype, the Convertawings Model A. The main body of the Convertawings Model A was made of steel, while the arms supporting the four rotors were made of aluminum. The control mechanism was greatly simplified and was achieved by differentially varying the thrust between the rotors. Power was provided by two motors connected to the rotor drive system by multiple V-belts. The shaft and transmission housings provided the interconnection between the four rotors, allowing both motors to operate the quadrotor when needed. Despite successful test flights, production of the Convertawings Model A was discontinued due to budget cuts within the US Army [82]. Figure 5 shows a photo of the Convertawings Model A taken in 1956 [83]. The technical specifications of the Convertawings Model A quadrotor are given in

Table 6. Technical specifications of the Convertawings Model A quadrotor.

Parameter	Value
Crew capacity	1 person
Gross weight	998 kg
Rotor diameter	5.92 m
Powerplant	2 × 90 hp Continental engine
Maximum speed	128 km/h

[84].

In 1958, the US company Curtiss-Wright produced the Curtiss-Wright VZ-7 quadrotor for use by the US military. The Curtiss-Wright VZ-7 had a pilot’s seat, fuel tanks, and a fuselage with flight controls. The quadrotor, which was controlled by varying the thrust of each propeller, was highly maneuverable and easy to fly. Its cruising speed was 25 mph (40 km/h), and it could reach a maximum speed of 31 mph (50 km/h). It could fly at an altitude of 200 ft (61 m). Although the VZ-7 performed well in tests, its production program was halted in 1960 because it did not meet military standards [85]. Figure 6 shows a photograph of the Curtiss-Wright VZ-7 quadrotor taken in 1958. The technical specifications of the Curtiss-Wright VZ-7 quadrotor are given in

Table 7. Technical specifications of the Curtiss-Wright VZ-7 quadrotor.

Parameter	Value
Crew capacity	1 person
Flight time	25 min
Empty weight	771 kg
Gross weight	953 kg
Length	5.18 m
Width	4.88 m
Height	2.84 m
Powerplant	425 hp Turbomeca Artouste IIB turboshaft engine
Maximum speed	50 km/h
Cruise speed	40 km/h
Service ceiling	61 m

[86].

In 1980, the US-based Piasecki Aviation company began designing a quadrotor for the US Navy to lift heavy loads. The Piasecki PA-97 quadrotor was produced for this purpose. The Piasecki PA-97 had an aluminum frame attached to the bottom of a helium-inflated airship. Four Sikorsky H-34J helicopters were attached to the aluminum frame. Criticisms were expressed regarding the structural properties and stress analysis of this frame. It made its first flight on 28 April 1986. On 1 July 1986, a test flight crashed shortly after takeoff, killing one pilot and injuring four others. Production of the Piasecki PA-97 was halted after this accident [87]. Figure 7 shows a photograph of the Piasecki PA-97 taken in 1986. The technical specifications of the Piasecki PA-97 are given in

Table 8. Technical specifications of Piasecki PA-97 quadrotor.

Parameter	Value
Crew capacity	1 person
Passenger capacity	7 people
Flight time	1 min
Gross weight	50,765 kg
Length	104.57 m
Diameter	23.17 m
Volume	28,628.33 m3
Powerplant	4× Wright R-1820-84C reciprocating, 1380 hp each

[88].

Due to the accidents experienced by pilot-operated quadrotors and their failure to meet US military standards, the use of manned quadrotors in the defense industry was abandoned. This led to the development of quadrotor unmanned aerial vehicles in the 1990s. After a hiatus of approximately 30 years, the mid-2010s saw the introduction of manned quadrotors as air taxis or by aerobatic pilots in demonstration competitions.

Ehang, a Chinese company founded in 2014, began producing manned quadrotors for use as air taxis. In 2015, the company produced the Ehang 184 passenger-carrying quadrotor. The Ehang is an electric quadrotor, controlled by an autopilot and capable of carrying one passenger. It can reach speeds of 130 km/h and operate at altitudes of 500 m. Its range is 16 km. Test flights were conducted in stormy, foggy, and night conditions. It began carrying passengers in 2015 and completed 40 successful trips by February 2018. A total of 40 were produced by July 2018. The Ehang 184 was the first quadrotor to enter mass production among the quadrotors capable of carrying passengers. The technical specifications of the Ehang 184 quadrotor are given in

Table 9. Technical specifications of Ehang 184 quadrotor.

Parameter	Value
Crew capacity	None (autopilot)
Passenger	1
Empty weight	260 kg
Takeoff weight	360 kg
Length	3.86 m
Wingspan	5.5 m
Height	1.44 m
Propellers	8 (2-bladed fixed pitch)
Power	106 kW
Flight time	25 min
Cruise speed	130 km/h
Service ceiling	500 m
Range	16 km

[89]. Figure 8 shows a photograph of the Ehang 184 quadrotor taken in 2016 [90].

In 2022, the Swedish company Jetson Aero produced the Jetson One quadrotor. This quadrotor was electric, piloted, and had a flight endurance of 20 min. The quadrotor weighed 115 kg and could reach a speed of 101 km/h. The quadrotor could continue to fly if it lost one of its propellers, but in such a case, it would prompt the pilot to make an emergency landing. Thanks to its onboard LIDAR (Light Detection and Ranging) sensor, the quadrotor automatically slows down upon approaching the ground, preventing a collision. The company received orders for each Jetson One quadrotor in 2022, priced at $92,000, and announced delivery in 2023 [91,92]. Figure 9 shows a photograph of the Jetson One. The technical specifications of the Jetson One are given in

Table 10. Technical specifications of the Jetson One quadrotor.

Parameter	Value
Crew capacity	1 (pilot)
Length	2.845 m
Width	2.4 m
Height	1.03 m
Empty mass	55 kg
Mass with batteries	115 kg
Maximum pilot weight	95 kg
Service ceiling	Above 457.2 m (1500 ft)
Maximum speed	102 km/h
Flight time	20 min
Battery	84 kW high-discharge Li-ion 52 V 20,700 mAh
Chassis	Aluminum Space Airframe
Motor	Electric Brushless

[92].

Airbus Helicopters began designing a manned quadrotor, called CityAirbus, for use as an air taxi in 2015. Testing of the quadrotor was completed in 2018. It made its maiden flight in 2019. It completed its first crewed flight in 2020. It has completed 242 flights over 1000 km in total. It is designed to carry a total of four passengers and be piloted. In 2021, Airbus announced that it had abandoned the quadrotor design and developed a new design with a fixed wing and V-tail [93]. In 2025, Airbus announced that it had also abandoned the fixed-wing design and discontinued the air taxi project [94].

Table 11. Technical specifications of CityAirbus quadrotor.

Parameter	Value
Crew capacity	1 (pilot)
Passenger capacity	4
Length	8 m
Wingspan	8 m
Maximum takeoff weight	2200 kg
Powerplant	8× Siemens SP200D 100 kW Direct Drive
Batteries	4 × 140 kW power (190 hp)
Propellers	2.8 m diameter
Cruise speed	120 km/h
Flight time	15 min

provides the technical specifications of CityAirbus [95]. Figure 10 shows a photo of CityAirbus in 2020 [96].

The salient features of manned quadrotors are given in

Table 12. The salient features of manned quadrotors.

Manned Quadrotor Model	Salient Feature
Gyroplane No. 1	First manned quadrotor
Gyroplane No.2	A quadrotor with a lighter mass and a more powerful engine, reaching a higher altitude than the previous version
Oehmichen No. 2	Longest-flying rotary-wing aircraft and first passenger-carrying manned quadrotor
de Bothezat quadrotor	The first quadrotor produced and patented for military purposes; it has the largest passenger carrying capacity and the most powerful engine.
Convertawings Model A	Fastest flying manned quadrotor
Curtiss-Wright VZ-7	Manned quadrotor with the longest flight duration
Piasecki PA-97	The first manned quadrotor designed to lift heavy loads
Ehang 184 quadrotor	The first air taxi and the first autopiloted manned quadrotor to enter mass production
Jetson One	Lightest and smallest manned quadrotor
CityAirbus	The air taxi with the most powerful electric motor and the highest passenger carrying capacity

. This table highlights the prominent features of manned quadrotor models based on the period in which they were produced.

Table 13. Selected technical specifications of manned quadrotors.

Model	Weight	Powerplant	Flight Time	Capacity
Gyroplane No. 1	578 kg	46 hp	1 min	1 person
Gyroplane No. 2	550 kg	55 hp	1 min	1 person
Oehmichen No. 2	1000 kg	180 hp	14 min	3 people
de Bothezat	1633 kg	220 hp	2 min 45 s	5 people
Convertawings Model A	998 kg	2 × 90 hp	-	1 person
Curtiss-Wright VZ-7	953 kg	425 hp	25 min	1 person
Piasecki PA-97	50,765 kg	4 × 1380 hp	1 min	8 people
Ehang 184	360 kg	106 kW (142 hp)	25 min	1 person
Jetson One	210 kg	84 kW (113 hp)	20 min	1 person
CityAirbus	2200 kg	4 × 140 kW (751 hp)	15 min	5 people

lists selected technical specifications of manned quadrotors. The table lists the weights, power, flight times, and capacities of manned quadrotors. The weight column in Table 13 shows the gross weights of manned quadrotors. The capacity of a manned quadrotor is given as the total capacity, including passengers and the pilot. The powerplant value of electric motor quadrotors in hp is given in parentheses. Manned quadrotors for which flight time data is not available are marked with a “-” symbol in the table.

The graph showing the gross weights of manned quadrotors is shown in Figure 11.

Figure 12 shows the powerplant graph of manned quadrotors. To use a single unit in the graph, the kW values in Table 13 were converted to hp. 1 kW corresponds to 1.342 hp.

Figure 13 shows the flight times of manned quadrotors. No flight time data was found for the Convertawings Model A, so it is not included in the graph.

Figure 14 shows the total passenger capacity of manned quadrotors, including the pilot.

When Figure 11 and Figure 14 are evaluated together, it is seen that the gross weight and passenger carrying capacity of manned quadrotors are directly proportional. As the passenger-carrying capacity of a manned quadrotor increases, its gross weight also increases. Furthermore, as the gross weight of a manned quadrotor increases, the required engine power also increases. As can be seen from Figure 12, heavy quadrotors have higher engine power.

Examining the powerplant values of the manned quadrotors in Figure 12, it is observed that there is a direct proportion between the weight increase and the powerplant value. This is because heavier quadrotors require more power to move. Additionally, starting with the Ehanag 184 manned quadrotor, fossil fuel engine-powered quadrotors have been replaced by electric motor quadrotors.

An examination of the flight times in Figure 13 reveals a general increasing trend in the flight times of manned quadrotors from Gyroplane No. 1, built in 1907, to the Ehang 184, built in 2015. The de Bothezat and Piasecki PA-97 quadrotors are two examples that contradict this trend. The shorter flight time of the de Bothezat quadrotor than the Oehmichen No. 2 quadrotor is due to the greater number of passengers and its greater weight. The Piasecki PA-97 quadrotor had a very short flight time as it had an accident shortly after take-off. The Jetson One quadrotor’s flight duration is shorter than the Ehang 184. This is due to the Jetson One’s smaller size and lower battery capacity than the Ehang 184. The CityAirbus flight duration is shorter than both the Ehang 184 and the Jetson One. This is due to the CityAirbus’s greater passenger capacity. While the CityAirbus carries five passengers, the Ehang 184 and Jtson One only carry one. The CityAirbus consumes more energy to carry five passengers, which shortens its flight time.

4. Development Stages of the Quadrotor Unmanned Aerial Vehicles

The high production cost, difficulty in controlling, limited range of use, and accidents associated with manned quadrotors have led to almost all manned quadrotors remaining in the prototype stage and not entering mass production. This has paved the way for the development of quadrotor unmanned aerial vehicles. Their small size, low production costs, and ease of control make them advantageous. Advances in hardware, software, sensor, battery, and camera technologies have led to the widespread use of quadrotor UAVs.

The first powered unmanned aerial vehicle was the Aerial Target, a fixed-wing UAV developed by British engineer Low in 1916. Numerous fixed-wing UAVs were produced in the following years, primarily for use in the defense industry [97]. However, these UAVs do not fall into the quadrotor UAV class because they are fixed-wing, take off from runways, and do not have four rotors. Quadrotor UAVs are UAVs with four rotors capable of vertical takeoff and landing. The development of quadrotor UAVs began in the 1990s. In 1999, the Canadian-based company Draganfly produced the Draganflyer I. In 2001, the company produced the first camera-equipped quadrotor UAV by attaching an integrated camera to the Draganflyer I quadrotor. The Draganflyer I is significant as it became the first quadrotor UAV to achieve large-scale mass production, moving the technology from a research curiosity to a commercial product [98]. A photograph of the Draganflyer I quadrotor is shown in Figure 15 [99].

Draganfly launched new models of the Draganflyer quadrotor in the early 2000s, with minor improvements. The series continued from the Draganflyer I, produced in 1999, to the Draganflyer V. Photographs of the Draganflyer III, IV, and V are shown in Figure 16.

The components of the Draganflyer V are shown in Figure 17. The Draganflyer V’s technical specifications are provided in

Table 14. Technical specifications of Draganflyer V.

Parameter	Value
Weight	454 g
Payload capacity	85 g
Motors	4× brushless DC motor
Battery	3-cell 1320 mAh
Maximum velocity	13.4 m/s
Camera	365 K (0.365 MP) PAL miniature camera
Flight time	13–17 min

[103].

Draganfly has developed drones with more advanced cameras, real-time video transmission, a larger payload, and longer flight endurance. These drones have been used by US and Canadian police in search and rescue operations and evidence collection since 2009 [104,105].

Draganfly company produced the quadrotor called X4-ES in 2013. In 2013, a Draganflyer X4-ES quadrotor was used by the Canadian Mounted Police to locate an injured man whose car had overturned in a remote wooded area in freezing weather. The injured man was located and treated. This marked the first time in history that a search and rescue quadrotor saved a human life [106]. The technical specifications of the Draganflyer X4-ES are provided in

Table 15. Technical specifications of Draganflyer X4-ES.

Parameter	Value
Length	87 cm
Width	87 cm
Height	29 cm
Diameter	1070 mm
Gross weight	2470 g
Weight without battery	1675 g
Maximum climb rate	2 m/s
Maximum descent rate	2 m/s
Maximum turn rate	90°/s
Flight speed	50 km/h
Maximum height	2438 m
Power	Rechargeable Li-Polymer Battery 5400 mAh
Camera	20.2 MP/1080P HD video
Flight time	20 min

[107]. A photograph of the Draganflyer X4-ES is shown in Figure 18 [108].

Following the X4-ES, Draganfly produced the Draganflyer Commander quadrotor in 2015, which boasted more advanced features. The Draganfly Commander quadrotor boasts longer flight endurance than the X4-ES, smoother takeoffs and landings, and can be controlled via a mobile phone app. It also features two battery packs to protect against battery failure [109]. The Commander quadrotor was developed for agricultural applications covering up to 100 acres, as well as land surveying, aerial 3D modeling, mapping, and search and rescue applications. The Draganflyer Commander’s technical specifications are provided in

Table 16. Technical specifications of Draganflyer Commander.

Parameter	Value
Length	87.3 cm
Width	87.3 cm
Height	29.46 cm
Diameter	107 cm
Gross weight	3750 g
Weight without battery	2750 g
Payload capacity	1000 g
Maximum climb rate	2 m/s
Maximum descent rate	2 m/s
Maximum turn rate	90°/s
Flight speed	50 km/h
Maximum height	2438 m
Power	2× Rechargeable Li-Polymer Battery 6750 mAh
Flight time	25–32 min
Camera	20.2 megapixel sensor with 30× optical zoom camera

[110].

Draganfly launched the Draganflyer Commander 2 in 2021. Compared to the previous generation, the Commander 2 features new operational capabilities, new sensors, new flight controls, and Mav-Link-based mission planning software. It also features a thermal camera. It was developed for agriculture, mapping, public safety, and photography. Technical specifications of Draganflyer Commander 2 are provided in

Table 17. Technical specifications of Draganflyer Commander 2.

Parameter	Value
Length	87.3 cm
Width	87.3 cm
Height	29.46 cm
Diameter	107 cm
Gross weight	3750 g
Weight without battery	2750 g
Payload capacity	1000 g
Maximum climb rate	2 m/s
Maximum descent rate	2 m/s
Maximum turn rate	90°/s
Flight speed	64 km/h
Maximum height	2438 m
Power	2× Rechargeable Li-Polymer Battery 6750 mAh
Flight time	32 min
Camera	24 MP RGB camera

[111].

Draganfly company launched the Draganflyer Commander 3 XL quadrotor in 2023. This quadrotor was developed for surveillance, mapping, and search and rescue missions, as well as heavy lifting. It has a payload capacity of up to 10 kg and features a 360-degree camera view. With a flight time of 50 min, it offers a longer flight time than previous Commander-series quadrotors. It can be customized using a variety of communication options such as Microhard PDDL, Herelink Blue, Doodle Labs Helix and DTC BluSDR. Microhard PDDL has a transmission range of up to 2 km, Herelink Blue up to 5 km, Doodle Labs Helix and DTC BluSDR up to 10 km. It has two batteries. Its flight speed of 72 km/h is approximately 1.5 times faster than previous drones in the series. The technical specifications of the Commander 3 XL quadrotor are given in

Table 18. Technical specifications of Draganflyer Commander 3 XL.

Parameter	Value
Length	91.4 cm
Width	93.9 cm
Height	30.4 cm
Maximum takeoff weight	25 kg
Empty weight	15 kg
Payload capacity	10 kg
Maximum climb rate	3 m/s
Maximum descent rate	3 m/s
Maximum turn rate	90°/s
Flight speed	72 km/h
Maximum height	2438 m
Power	2× Rechargeable Li-Polymer Battery 16,000 mAh
Flight time	50 min
Thermal Camera	FLIR Duo Pro R Thermal Camera with 30 Hz
Photography Camera	24 MP RGB Photography Camera
Standard Camera	10× Zoom RGB Camera
Mapping Camera	24 MP RGB Mapping Camera
Alternative Mapping Camera	Rededge MX Mapping Camera
Surveillance Camera	Gremsy Surveillance Camera

[112,113].

Draganfly company launched the Draganflyer Commander 3 XL Hybrid quadrotor in 2024. Because the Commander 3 XL Hybrid operates using gasoline or heavy fuels, it has a much longer flight time than previous drones in the Commander series. The technical specifications of the Commander 3 XL Hybrid quadrotor are given in

Table 19. Technical specifications of Draganflyer Commander 3 XL Hybrid.

Parameter	Value
Length	162 cm
Width	160 cm
Height	30 cm
Maximum takeoff weight	25 kg
Maximum payload weight	4 kg
Maximum climb rate	3 m/s
Maximum descent rate	3 m/s
Maximum turn rate	90°/s
Flight speed	72 km/h
Maximum height	2438 m
Engine	Draganfuel-Ignite 70 cc two-stroke Pegasus engine
Flight time	3 h
Engine base weight	3.5 kg
Maximum power output	4000 W
Operating voltage	24 V through 50 V
Fuel type	Gasoline 87 Oct & higher or multifuel
Ignition	Capacitive discharge
Camera	24 MP 10× Zoom RGB Camera

[114].

Photographs of the Draganflyer Commander, Commander 2, Commander 3 XL and Commander 3 XL hybrid are shown in Figure 19.

In 2010, the French company Parrot developed the Parrot AR.Drone, a quadrotor controlled via apps installed on iOS and Android mobile phones and tablets. Its body is made of nylon and carbon fiber for a lightweight design. It has two interchangeable bodies for indoor and outdoor use. The indoor body wraps around the wings for protection. The onboard computer runs a Linux operating system and communicates with the pilot via a self-generated Wi-Fi access point. The rotors are powered by an 11.1-volt lithium polymer battery. It has four 15-watt brushless motors. This provides a flight time of approximately 12 min at 5 m/s. The quadrotor’s body is 57 cm in diameter and has USB and Wi-Fi 802.11b/g interfaces. The front camera is a QVGA sensor with a 93° lens. The vertical camera has a 64° lens, recording up to 60 fps. The technical specifications of the Parrot AR.Drone are provided in

Table 20. Technical specifications of Parrot AR.Drone.

Parameter	Value
Length	57 cm
Width	57 cm
Height	14 cm
Indoor weight	380 g
Outdoor weight	420 g
Interfaces	USB and Wi-Fi 802.11b/g
Front Camera	480p (0.3 MP) sensor with 93° lens, recording up to 30 fps
Vertical Camera	QVGA sensor with 64° lens, recording up to 60 fps
Flight speed	5 m/s
Flight time	12 min
Wind resistance	4.17 m/s (15 km/h)
Battery	Lithium-polymer 3-cell, 1000 mAh
Motors	4× brushless 14.5-watt

[119].

In 2012, the Parrot AR.Drone 2.0 was released. The camera quality was improved to 720p (0.9 MP). New, more sensitive sensors were used. The Wi-Fi hardware was upgraded to meet the 802.11n standard. The indoor and outdoor versions of the Parrot AR.Drone 2.0 are shown in Figure 20. The indoor version is shown on the left of Figure 20, and the outdoor version is shown on the right. The technical specifications of the Parrot AR.Drone 2.0 are provided in

Table 21. Technical specifications of Parrot AR.Drone 2.0.

Parameter	Value
Length	57 cm
Width	57 cm
Height	14 cm
Indoor weight	380 g
Outdoor weight	420 g
Interfaces	USB and Wi-Fi 802.11n
Front Camera	720p (0.9 MP) sensor with 93° lens, recording up to 30 fps
Vertical Camera	QVGA sensor with 64° lens, recording up to 60 fps
Flight speed	5 m/s
Flight time	12 min
Wind resistance	4.17 m/s (15 km/h)
Battery	Lithium-polymer 3-cell, 1500 mAh
Motors	4× brushless 14.5-watt

[120].

The Parrot AR.Drone has become one of the best-selling quadrotors in the world, with over 500,000 units sold by 2014 [121]. The Parrot AR.Drone received the CES (Consumer Electronics Show) Innovations Award in 2010 [122]. The Parrot AR.Drone was a pivotal model that made drone technology available for the masses. Its control via smartphone apps and its game-like interface created an entirely new consumer market for quadrotors, positioning them as accessible gadgets rather than specialized tools. In 2012, Parrot acquired 57% of the drone company SenseFly, a spin-off of EPFL, and 25% of the photogrammetry company Pix4D, also a spin-off of EPFL [123]. In 2014, it increased its ownership in Pix4D to 57% [124]. In 2023, Parrot signed a strategic partnership agreement with Tinamu, a spin-off of ETH Zurich. Under this agreement, Tinamu committed to developing software that would enable Parrot’s drones to self-navigate in challenging indoor environments [125].

In 2014, Parrot produced the AR.Drone 3.0, codenamed Bebop. The AR.Drone 3.0 featured a more advanced camera than previous versions, a more robust Wi-Fi connection, and could fly up to 2 km using the Skycontroller. It can also be controlled via a mobile application downloaded to Android and iOS mobile phones. Images of the Parrot Bebop and Skycontroller are shown in Figure 21. The technical specifications of the Parrot Bebop drone are shown in

Table 22. Technical specifications of Parrot Bebop.

Parameter	Value
Length	32 cm
Width	28 cm
Height	3.6 cm
Weight	400 g
Wi-Fi	Wi-Fi 802.11 a/b/g/n/ac and Wi-Fi 2.4 and 5 GHz
Camera	14 MP fish-eye camera with 180° field
Flight speed	13 m/s
Flight time	12 min
Wind resistance	11.11 m/s (40 km/h)
Transmission distance	2 km
Battery	Lithium Polymer 1200 mAh

[126,127].

Parrot released the Bebop 2 model in 2015. This model has a longer flight time, a more powerful battery, a longer Wi-Fi range, a higher-quality camera, and an image stabilization system. It can also fly faster than the previous model and withstand higher wind speeds, and has a more advanced Skycontroller. Figure 22 shows the Parrot Bebop 2 drone and the Skycontroller black edition. The technical specifications of the Parrot Bebop 2 drone are shown in

Table 23. Technical specifications of Parrot Bebop 2.

Parameter	Value
Length	32.8 cm
Width	38.2 cm
Height	8.9 cm
Weight	500 g
Wi-Fi	Wi-Fi 802.11 a/b/g/n/ac and Wi-Fi 2.4 and 5 GHz
Camera	14 MP fish-eye camera with 180° field
Flight speed	16 m/s
Flight time	25 min
Wind resistance	11.11 m/s (40 km/h)
Transmission distance	2 km
Battery	Lithium Polymer 2700 mAh

[128,129].

In 2018, Parrot produced the ANAFI quadrotor with 4K HDR and a 21-megapixel camera. Parrot received $11 million in funding from the U.S. Department of Defense in 2019 to develop a prototype of a next-generation reconnaissance drone that “can fly continuously for 30 min at a range of up to 3 km,” weighs 3 pounds or less, and “takes less than 2 min to assemble and fit into a soldier’s standard backpack”. A photo of the Parrot ANAFI is shown in Figure 23 [130,131]. The Parrot ANAFI comes with a Skycontroller 3. By connecting a mobile phone to the Skycontroller 3, a connection is established between the mobile phone’s screen and the quadrotor’s camera. Figure 24 shows an image of the Skycontroller 3 [132]. The technical specifications of the Parrot ANAFI are provided in

Table 24. Technical specifications of Parrot ANAFI.

Parameter	Value
Length	17.5 cm
Width	24 cm
Height	6.5 cm
Weight	320 g
Wi-Fi	Wi-Fi 802.11 a/b/g/n and Wi-Fi 2.4 and 5.8 GHz
Camera	21 MP (5344 × 4016)/4:3/84° HFOV
Flight speed	15 m/s
Flight time	25 min
Wind resistance	13.89 m/s (50 km/h)
Transmission distance	4 km
Battery	High-Density Lipo (2 cells) 2700 mAh
Operating temperature	−10 °C to +40 °C

[133].

In 2020, Parrot produced the ANAFI USA drone. The ANAFI USA drone was used by several NATO countries (the United States, UK, France, Italy, Belgium, Sweden, Finland, Poland, Spain, Luxembourg) and Japan, Australia, Singapore, and Malaysia [134]. In 2021, Parrot signed a contract with the French army for 300 drones [135]. The ANAFI USA features a 32× zoom, a thermal camera, and high cybersecurity with data encryption. It is ready for flight in as little as 55 s. The image of the ANAFI USA drone is shown in Figure 25. The technical specifications of the Parrot ANAFI USA are provided in

Table 25. Technical specifications of Parrot ANAFI USA.

Parameter	Value
Length	28.2 cm
Width	37.3 cm
Height	8.2 cm
Weight	500 g
Wi-Fi	Wi-Fi 802.11 a/b/g/n 2.4 GHz, UNII-1 & UNII-3
Camera	21 megapixel 84° FOV
Flight speed	14.7 m/s
Flight time	32 min
Wind resistance	15 m/s (54 km/h)
Transmission distance	5 km
Battery	High-density LiPo (3 × 4.4 V cells) 3400 mAh
Operating temperature	−36 °C to +50 °C

[136].

In 2021, Parrot produced the Parrot ANAFI Ai quadrotor for inspection and mapping. ANAFI Ai has a 48 MP camera, 4G connectivity, can perform automated missions and protects user data. The ANAFI Ai is the first drone to utilize 4G connectivity. The ANAFI Ai can automatically find the best trajectory for its mission. The ANAFI Ai features an omnidirectional camera that can rotate in all directions. A photograph of the ANAFI Ai and Skycontroller 4 is given in Figure 26. Unlike previous controllers, the new Skycontroller 4 offers an HDMI input. It is also compatible with the iPad Mini and larger smartphones [137]. The technical specifications of the Parrot ANAFI Ai are provided in

Table 26. Technical specifications of Parrot ANAFI Ai.

Parameter	Value
Length	32 cm
Width	44 cm
Height	11.8 cm
Weight	898 g
Wi-Fi	Wi-Fi 802.11 a/b/g/n & 4G
Camera	48 MP
Flight speed	16 m/s
Flight time	32 min
Wind resistance	14 m/s (50.4 km/h)
Transmission distance	9 km
Battery	High-density Lithium Polymer (262 Wh/kg) 3.350 mAh
Operating temperature	−10 °C to +40 °C

[138].

China-based DJI has produced numerous quadrotors for aerial photography and videography. In 2013, it released the DJI Phantom 1. The DJI Phantom 1 did not include a built-in camera. However, a GoPro HERO 3 camera could be optionally mounted on the DJI Phantom 1. The DJI Phantom 1’s technical specifications are listed in

Table 27. Technical specifications of the DJI Phantom 1.

Parameter	Value
Diagonal distance	35 cm
Weight	670 g
Working frequency	2.4 GHz ISM
Camera	GoPro HERO 3 12 MP
Communication distance	1000 m
Flight speed	10 m/s
Flight time	15 min
Battery	LiPo 2200 mAh
Operating temperature	−10 °C to +50 °C

[139]. A photo of the DJI Phantom 1 with a GoPro HERO 3 camera is provided in Figure 27 [140].

The DJI Phantom 1 defined the modern consumer drone platform by integrating GPS and sophisticated flight controllers, which provided remarkable stability and ease of use, thereby unlocking the potential for reliable aerial photography and videography.

In late 2013, DJI released the DJI Phantom 2 Vision. The DJI Phantom 2 Vision features a 14 MP camera and a flight time of 25 min. It has a longer flight time than the DJI Phantom 1, a more powerful battery, and is faster and heavier. The technical specifications of the DJI Phantom 2 Vision are provided in

Table 28. Technical specifications of the DJI Phantom 2 Vision.

Parameter	Value
Diagonal distance	35 cm
Weight	1000 g
Working frequency	2.4 GHz ISM
Camera	14 MP
Communication distance	1000 m
Flight speed	15 m/s
Flight time	25 min
Wind resistance	8 m/s (28.8 km/h)
Battery	3S LiPo LiPo 5200 mAh
Operating temperature	−10 °C to +50 °C

[141]. The image of the DJI Phantom 2 Vision is shown in Figure 28 [142].

DJI released the Phantom 3 quadrotor in 2015. The Phantom 3 is faster and weighs more than the Phantom 2. The maximum flight time and dimensions of the Phantom 2 and Phantom 3 are the same. Their operating frequency is the same. The DJI Phantom 3 has a 12-megapixel camera capable of recording 2.7 K video at 30 fps and a 94-degree field of view, ideal for wide-angle shots. A photo of the DJI Phantom 3 is shown in Figure 29. The technical specifications of the DJI Phantom 3 are shown in

Table 29. Technical specifications of the DJI Phantom 3.

Parameter	Value
Diagonal distance	35 cm
Weight	1216 g
Working frequency	2.4 GHz ISM
Camera	12 MP
Communication distance	1000 m
Flight speed	16 m/s
Flight time	25 min
Wind resistance	10 m/s (36 km/h)
Battery	LiPo 4S 4480 mAh
Operating temperature	0 °C to +40 °C

[143].

DJI released the Phantom 4 quadrotor in 2016. Its flight time is longer than that of other quadrotors in the Phantom series. It is faster than all previous quadrotors in the series and has a more powerful battery. It has a 12.4-megapixel camera. The technical specifications of the DJI Phantom 4 are given in

Table 30. Technical specifications of the DJI Phantom 4.

Parameter	Value
Diagonal distance	35 cm
Weight	1380 g
Working frequency	2.4 GHz ISM
Camera	12 MP
Communication distance	1000 m
Flight speed	20 m/s
Flight time	28 min
Wind resistance	10 m/s (36 km/h)
Battery	LiPo 2S 6000 mAh
Operating temperature	0 °C to +40 °C

. A photograph of the DJI Phantom 4 is given in Figure 30 [144].

DJI released the Mavic Pro quadrotor in 2016. It features foldable arms for easy transport. The Mavic Pro is equipped with the same 12-megapixel camera as the Phantom 4. It has a 78-degree field of view, as opposed to the Phantom 4’s 94-degree field of view. Its top speed is 65 km/h, its range is 6.9 km, and it is powered by a 3830 mAh battery. It has a flight time of 27 min. The technical specifications of the DJI Mavic Pro quadrotor are given in

Table 31. Technical specifications of the DJI Mavic Pro.

Parameter	Value
Length	19.8 cm
Width	8.3 cm
Height	8.3 cm
Weight	743 g
Wi-Fi	2.4–2.4835 GHz; 5.150–5.250 GHz; 5.725–5.850 GHz
Working frequency	2.4 GHz and 5.8 GHz
Camera	12 MP
Maximum flight distance	13 km
Maximum transmission distance	7 km
Flight speed	17.88 m/s
Flight time	27 min
Wind resistance	10 m/s (36 km/h)
Battery	LiPo 3S 3830 mAh
Operating temperature	0 °C to +40 °C

[145].

DJI released the Mavic 2 Pro in 2018. The Mavic 2 features 10 obstacle avoidance sensors. The battery capacity has been increased to 3850 mAh. The maximum flight time is 31 min. The Mavic 2 Pro features a 20-megapixel camera. The technical specifications of the DJI Mavic 2 Pro quadrotor are provided in

Table 32. Technical specifications of the DJI Mavic 2 Pro.

Parameter	Value
Length	32.2 cm
Width	9.1 cm
Height	8.4 cm
Weight	907 g
Wi-Fi	2.400–2.483 GHz; 5.725–5.850 GHz
Working frequency	2.4 GHz and 5.8 GHz
Camera	20 MP
Maximum flight distance	18 km
Maximum transmission distance	10 km
Flight speed	20 m/s
Flight time	31 min
Wind resistance	10 m/s (36 km/h)
Battery	LiPo 4S 3850 mAh
Operating temperature	−10 °C to +40 °C

[146].

DJI released the Mavic 3 quadrotor in 2021. The Mavic 3 has a flight time of 46 min. It features both a wide-angle and a telephoto camera. The wide-angle camera is 20 MP, while the telephoto camera is 12 MP. It connects to a 4G mobile network and can be controlled from a range of up to 15 km. The technical specifications of the DJI Mavic 3 quadrotor are listed in

Table 33. Technical specifications of the DJI Mavic 3.

Parameter	Value
Length	34.75 cm
Width	9.63 cm
Height	9.03 cm
Weight	895 g
Working frequency	2.400–2.4835 GHz; 5.725–5.850 GHz
Camera	20 MP
Maximum flight distance	30 km
Maximum transmission distance	15 km
Flight speed	15 m/s
Flight time	46 min
Wind resistance	12 m/s (43.2 km/h)
Battery	Li-ion 4S 5000 mAh
Operating temperature	−10 °C to +40 °C

[147].

DJI released the Mavic 4 Pro in 2025. The Mavic 4 Pro has a 6654 mAh battery and a flight endurance of 51 min. It has three cameras: a variable-aperture 100 MP wide-angle camera capable of 6K video, a 1/1.3” CMOS telephoto camera, and a 1/1.5” CMOS medium telephoto camera. It features a more advanced obstacle avoidance system and satellite-independent return-to-home capability. It also features a 30 km HD video transmission capability. The Mavic 4 Pro’s technical specifications are listed in

Table 34. Technical specifications of the DJI Mavic 4 Pro.

Parameter	Value
Length	32.87 cm
Width	39.05 cm
Height	13.52 cm
Weight	1063 g
Wi-Fi	802.11 a/b/g/n/ac/ax
Working frequency	2.4 GHz and 5.8 GHz
Camera	100 MP
Maximum flight distance	41 km
Maximum transmission distance	30 km
Flight speed	18 m/s
Flight time	51 min
Wind resistance	12 m/s (43.2 km/h)
Battery	Li-ion 4S 6654 mAh
Operating temperature	−10 °C to +40 °C

[148].

Photos of the DJI Mavic Pro, Mavic 2 Pro, Mavic 3, and Mavic 4 Pro are given in Figure 31.

DJI has produced numerous quadrotor, hexarotor, and octorotor UAVs for use in agricultural spraying. In 2020, DJI launched the Agras T10 quadrotor model for agricultural spraying. The T10 features an 8 L tank, omnidirectional obstacle avoidance radar, dual cameras, and four nozzles. It has a 9500 mAh battery. The T10 has a hover time of 17 min with a takeoff weight of 16.8 kg. The technical specifications of the DJI Agras T10 quadrotor are given in

Table 35. Technical specifications of the DJI Agras T10.

Parameter	Value
Length	195.8 cm
Width	183.3 cm
Height	55.3 cm
Weight	16.8 kg
Spray tank volume	8 L
Operating payload	8 kg
Operating frequency	2.40–2.48 GHz; 5.15–5.25 GHz; 5.72–5.85 GHz
Camera	12 MP FPV
Effective safe obstacle avoidance speed	7 m/s
Maximum speed	10 m/s
Maximum transmission distance	5 km
Internal battery runtime	2 h
External battery runtime	2 h
Remote controller model	RM500-ENT
Remote controller screen	5.5-inch screen
Wind resistance	8 m/s (28.8 km/h)
Battery	9500 mAh
Operating temperature	0 °C to +40 °C

[153].

In 2022, DJI released the Agras T25 model. The Agras T25 can carry a spraying load of up to 20 kg or a spreading load of up to 25 kg. The Agras T25 features front and rear phased array radars, a binocular vision system, and a high-resolution FPV gimbal camera. It has a 15,500 mAh battery. The maximum diagonal wheelbase is 1925 mm. Internal battery operating time is 3 h and 18 min. External battery operating time is 2 h and 42 min. The technical specifications of the Agras T25 are given in

Table 36. Technical specifications of the DJI Agras T25.

Parameter	Value
Length	258.5 cm
Width	267.5 cm
Height	78 cm
Weight	32 kg
Spray tank volume	20 L
Operating payload	20 kg
Operating frequency	2.40 to 2.48 GHz, 5.275 to 5.850 GHz
Camera	12 MP FPV
Effective safe obstacle avoidance speed	10 m/s
Maximum speed	10 m/s
Maximum transmission distance	7 km
Internal battery runtime	3 h 18 min
External battery runtime	2 h 42 min
Remote controller model	RM700B
Remote controller screen	7.02-in LCD touchscreen
Wind resistance	6 m/s (21.6 km/h)
Battery	15,500 mAh
Operating temperature	0 °C to +40 °C

[154].

DJI produced the Agras T70P quadrotor in 2024. It has a 70 L spray tank and a flow rate of 40 L/min. It can carry a 70 kg spreading load and a flow rate of 400 kg/min. It also features obstacle avoidance capabilities. It can reach a maximum speed of 20 m/s and has a lift capacity of 65 kg. The technical specifications of the DJI Agras T70P are listed in

Table 37. Technical specifications of the DJI Agras T70P.

Parameter	Value
Length	320 cm
Width	352 cm
Height	96 cm
Weight	56 kg
Spray tank volume	70 L
Operating payload	70 kg
Lifting load capacity	65 kg
Lifting cable length	10–15 m
Operating frequency	Broadcast mode: O4: 2.4G/5.8G
Camera	12 MP FPV
Maximum configurable flight radius	2 km
Effective safe obstacle avoidance speed	13.8 m/s
Maximum speed	20 m/s
Maximum transmission distance	8 km
Internal battery runtime	3.8 h
External battery runtime	3.2 h
Remote controller model	TKPL 2
Remote controller screen	7-inch LCD touchscreen
Wind resistance	6 m/s (21.6 km/h)
DB1580 intelligent flight battery	30,000 mAh
DB2160 intelligent flight battery	41,000 mAh
Operating temperature	0 °C to +40 °C

[155].

Photos of the DJI Agras T10, Agras T25, and Agras T70P are provided in Figure 32.

In 2013, the Swedish company Bitcraze produced the Crazyflie nano quadrotor. The Crazyflie is one of the smallest and lightest quadrotor UAVs. The Crazyflie nano-quadrotor established itself not as a commercial product, but as a crucial open-source research platform. Its small size, modularity, and programmability made it the standard for universities and research institutions worldwide for testing control strategies, obstacle avoidance, and pioneering swarm robotics algorithms. The technical specifications of the Crazyflie quadrotor are given in

Table 38. Technical specifications of Bitcraze Crazyflie 1.0.

Parameter	Value
Motor-to-motor distance	9 cm
Weight	19 g
Microcontroller	32-bit MCU: STM32F103CB
Gyroscope	3-axis InvenSense MPU-6050
Accelerometer	3-axis InvenSense MPU-6050
Flight time	7 min
Battery	Li-Po 170 mAh

[159]. A photograph of the Crazyflie quadrotor is shown in Figure 33 [160].

Bitcraze produced the Crazyflie 2.0 quadrotor in 2014. It weighs 27 g. It supports wireless control via radio and Bluetooth Low Energy. It has a flight time of 7 min and a charging time of 40 min. iOS and Android mobile apps have been developed for controlling the Crazyflie 2.0. A photo of the Crazyflie 2.0 is shown in Figure 34. The technical specifications of the Crazyflie 2.0 are given in

Table 39. Technical specifications of Bitcraze Crazyflie 2.0.

Parameter	Value
Length	2.9 cm
Width	9.2 cm
Height	9.2 cm
Weight	27 g
Maximum recommended payload	15 g
Radio specification	2.4 GHz ISM band radio
Microcontroller	STM32F405 main application MCU
Gyroscope	3-axis MPU-9250
Accelerometer	3-axis MPU-9250
Magnetometer	3-axis MPU-9250
Pressure sensor	LPS25H
Flight time	7 min
Battery	Li-Po 240 mAh

[161].

Bitcraze released the Crazyflie 2.1 quadrotor in 2019. It offers improved radio performance and external antenna support. It features a more robust and break-resistant power button. A cable drain is used to prevent cables from weakening and breaking. The IMU and pressure sensor have been improved to improve flight performance. The Crazyflie 2.1 uses the BMI088 and BMP388 sensors, developed specifically for the drone by Bosch Sensortech. These sensors reduce drift [162]. A picture of the Crazyflie 2.1 is shown in Figure 35. The technical specifications of the Crazyflie 2.1 are shown in

Table 40. Technical specifications of Bitcraze Crazyflie 2.1.

Parameter	Value
Length	2.9 cm
Width	9.2 cm
Height	9.2 cm
Weight	29 g
Maximum recommended payload	15 g
Radio specification	2.4 GHz ISM band radio
Microcontroller	STM32F405 main application MCU
Gyroscope	3-axis BMI088
Accelerometer	3-axis BMI088
Pressure sensor	BMP388
Flight time	7 min
Battery	Li-Po 250 mAh

[163].

Bitcraze released the Crazyflie 2.1+ quadrotor in 2024. The Crazyflie 2.1+ features an upgraded battery and propellers compared to the Crazyflie 2.1, and offers up to 15% improved flight performance. The Crazyflie 2.1+’s battery has been lightened by 1 g to improve flight performance while maintaining the same capacity. The technical specifications of the Crazyflie 2.1+ quadrotor are shown in

Table 41. Technical specifications of Bitcraze Crazyflie 2.1+.

Parameter	Value
Length	2.9 cm
Width	9.2 cm
Height	9.2 cm
Weight	29 g
Maximum recommended payload	15 g
Radio specification	2.4 GHz ISM band radio
Microcontroller	STM32F405 main application MCU
Gyroscope	3-axis BMI088
Accelerometer	3-axis BMI088
Pressure sensor	BMP388
Flight time	7 min
Battery	Li-Po 250 mAh

[164]. A photograph of the Crazyflie 2.1+ is shown in Figure 36 [165].

Bitcraze produced the Crazyflie 2.1 Brushless quadrotor in 2025. Thanks to its brushless motors, the Crazyflie 2.1 Brushless can lift heavier loads and achieve more powerful flights. A photo of the Crazyflie 2.1 Brushless quadrotor is shown in Figure 37. The technical specifications of the Crazyflie 2.1 Brushless quadrotor are given in

Table 42. Technical specifications of Bitcraze Crazyflie 2.1 Brushless.

Parameter	Value
Motor-to-motor distance	10 cm
Takeoff weight with legs	34 g
Takeoff weight with guards	37 g
Maximum recommended payload	40 g
Radio specification	2.4 GHz ISM band radio
Microcontroller	STM32F405 main application MCU
Gyroscope	3-axis BMI088
Accelerometer	3-axis BMI088
Pressure sensor	BMP388
Flight time	10 min
Battery	Li-Po 350 mAh

[166].

Founded in 2009 in Berkeley, California, 3D Robotics (3DR) has produced quadrotors for aerial photography and mapping, and has developed the open-source ArduPilot autopilot software that can be used for quadrotors [167]. Its Iris+ and Solo drones catered to hobbyists, researchers, and developers, promoting a vibrant community and accelerating innovation in autonomous flight algorithms. In 2014, 3D Robotics produced the IRIS+ quadrotor. The IRIS+ could take photos with a mounted GoPro camera. It could reach speeds of 64 km/h and had a range of 3280 ft (1 km). The technical specifications of the IRIS+ quadrotor are shown in

Table 43. Technical specifications of 3DR IRIS+.

Parameter	Value
Motor-to-motor distance	55 cm
Weight with battery	1282 g
Maximum payload	400 g
Camera	GoPro Hero 4 12 MP
Autopilot hardware	32-bit Pixhawk with Cortex M4 processor
GPS	uBlox GPS with integrated magnetometer
Telemetry	3DR Radio 915 mHz or 433 mHz
Controller	FlySky FS-TH9x RC
Motors	950 kV
Flight time	16–22 min
Transmission distance	1 km
Battery	Lithium-polymer 3-cells 5100 mAh

[168]. Iris+ was the first consumer drone capable of tracking its user. A photograph of the IRIS+ quadrotor is shown in Figure 38 [169].

3D Robotics produced the Solo Drone quadrotor in 2015. The Solo Drone was designed specifically for the GoPro Hero camera. It was developed to enable professional aerial photography and video capture during flight. Solo can be controlled from a smartphone, with the ability to take photos and record videos with the application installed on Android and iOS devices. The technical specifications of the Solo quadrotor are shown in

Table 44. Technical specifications of 3DR Solo.

Parameter	Value
Motor-to-motor distance	46 cm
Height	25 cm
Weight	1500 g
Weight with GoPro and gimbal	1800 g
Maximum payload	420 g
Camera	GoPro Hero 3, 3+ and 4 12 MP
Autopilot hardware	Pixhawk 2
Autopilot software	APM: Copter
Communication	3DR Link secure Wi-Fi network
Frequency	2.4 GHz
Motors	880 kV brushless
Flight time	20–25 min
Maximum speed	24.72 m/s (89 km/h)
Transmission distance	800 m
App requirements	iOS 8.0 or later/Android 4.3 or later
Battery	Lithium-polymer 5200 mAh 14.8 V

[170]. A photograph of the Solo quadrotor is shown in Figure 39 [171].

3D Robotics played a critical role in making drone technology more accessible through its open-source ArduPilot 4.6.3 software. ArduPilot enables flight control of multirotor drones, VTOL UAVs, fixed-wing UAVs, and RC helicopters [172]. ArduPilot autopilot software works with the PID controller [173]. The first version of ArduPilot was released in 2009 [174]. Parrot company used ArduPilot autopilot software in its own quadrotors [175]. In 2016, 3D Robotics left the ArduPilot development community due to a dispute over the licensing of the open-source code. The PX4 Development Team and Community began developing the other mainstream autopilot software, the PX4 autopilot v1.16.0 software, in 2009 [176]. Like Ardupilot, the PX4 autopilot software was developed to work with a PID controller [177]. In 2014, the PX4 autopilot development community, 3D Robotics, and the Ardupilot autopilot development community produced the Pixhawk flight controller hardware. The flight controller hardware standardized by Pixhawk is used in academic, professional, and hobbyist applications and is supported by two common autopilot firmware options: PX4 and ArduPilot [178]. Today, advanced Pixhawk flight controllers contain two microcontrollers. The main flight management processor manages sensor readings, PID adjustments, and other resource-intensive computations. Another management processor handles input/output operations to external motors, switches, and radio control receivers. Onboard sensors include an IMU with a multi-axis accelerometer and gyroscope, a magnetometer, and a GPS unit [179]. Crazyflie quadrotors use the Crazyflie Bolt flight card and PX4 autopilot software. The flight card and autopilot software used by Crazyflie operate using a PID controller [180]. The Draganfly company uses the Cube Blue H7 flight control card, which is compatible with the PX4 autopilot software [181]. Researchers have developed many different linear and nonlinear controllers for quadrotors through simulations and theoretical studies. However, existing flight cards and autopilot software in the industry are designed to work with PID controllers.

An examination of the technical specifications of quadrotor UAVs reveals that early quadrotor UAVs had 2S Li-Po batteries. Quadrotor UAVs produced in later years had 3S and 4S Li-Po batteries, respectively. This suggests that the number of cells in quadrotor UAV batteries has increased over time. Increasing the number of cells in Li-Po batteries allows the battery to produce more power. This allows quadrotors to move faster and maneuver more quickly. Throughout the historical development process, increasing the number of cells in the batteries of quadrotor UAVs has had a positive impact on their speed.

Table 45. The salient features of quadrotor UAVs.

Quadrotor UAV Model	Salient Feature
Draganflyer I	First commercial quadrotor UAV to enter large-scale production
Draganflyer V	Quadrotor of the Draganflyer series with a miniature camera and a 3-cell battery
Draganflyer X4-ES	The first quadrotor to save a human life in a search and rescue operation
Draganflyer Commander	A quadrotor that can be controlled via a mobile application and is resistant to battery failures and is used in agriculture, 3D aerial modeling, mapping, and search and rescue operations
Draganflyer Commander 2	Quadrotor with thermal camera and MAV-Link-based mission planning software
Draganflyer Commander 3 XL	The fastest quadrotor in the Commander series with a 10 kg payload capacity and a 360-degree camera view
Draganflyer Commander 3 XL Hybrid	Quadrotor with a 70 cc two-stroke Pegasus engine and the longest flight time in the Commander series at 3 h
Parrot AR.Drone	The first quadrotor controlled by a mobile app
Parrot AR.Drone 2.0	One of the best-selling quadrotors in the world with over 500,000 units sold
Parrot Bebop	Quadrotor with 2 km transmission range, robust Wi-Fi connection and fisheye camera
Parrot Bebop 2	Compared to Bebop, longer flight time, a more powerful battery, a longer Wi-Fi range, a higher-quality camera, and an image stabilization system
Parrot ANAFI	4 km transmission distance (twice that of previous Parrot quadrotors), 13.89 m/s wind resistance and 21 MP camera
Parrot ANAFI USA	The first Parrot quadrotor sold to NATO countries, the first Parrot quadrotor with a 3-cell battery, the best-featured Parrot quadrotor ever with 15 m/s wind resistance and 5 km transmission range
Parrot ANAFI Ai	The first quadrotor with 4G connectivity, the Parrot quadrotor with the longest transmission distance of 9 km, the longest flight time of 32 min and the highest camera resolution of 48 MP
DJI Phantom 1	DJI’s first consumer quadrotor for aerial photography and videography with integrated GPS
DJI Phantom 2 Vision	DJI’s first quadrotor with a built-in camera. It’s faster than the Phantom 1, has a more powerful battery, and offers longer flight time
DJI Phantom 3	DJI’s first quadrotor with a 4-cell LiPo battery. It’s faster than the Phantom 2 and features 2.7 K video at 30 fps and a 94-degree field of view
DJI Phantom 4	The fastest and most powerful battery-powered quadrotor in the Phantom series
DJI Mavic Pro	DJI’s fastest quadrotor at 17.88 m/s and with the longest transmission range at 6.9 km
DJI Mavic 2 Pro	DJI’s fastest quadrotor with a flight speed of 20 m/s. It features 10 obstacle avoidance sensors and a transmission range of 10 km
DJI Mavic 3	DJI’s quadrotor with a transmission range of 15 km and a flight time of 46 min. It has a more powerful battery, longer flight time, and longer transmission range than DJI’s previous quadrotors
DJI Mavic 4 Pro	The quadrotor with the highest camera resolution at 100 MP. DJI’s quadrotor has the longest flight range at 41 km and the longest transmission range at 30 km. It also has the most powerful battery in the Mavic series
DJI Agras T10	DJI’s lowest-capacity agricultural spraying quadrotor
DJI Agras T25	DJI’s quadrotor, which performs both agricultural spraying and fertilizing, has a higher capacity and longer flight endurance than the T10
DJI Agras T70P	DJI’s quadrotor offers the highest spraying capacity at 70 L and the highest fertilizing capacity at 70 kg. It also boasts the longest flight time in the Agras series at 3.8 h
Bitcraze Crazyflie 1.0	The first quadrotor in the Crazyflie series. A palm-sized, open-source, and programmable quadrotor
Bitcraze Crazyflie 2.0	A quadrotor with a more powerful battery, a more advanced microcontroller, and more advanced sensors than the Crazyflie 1.0
Bitcraze Crazyflie 2.1	Bitcraze’s first quadrotor with external antenna support. It’s more shatter-resistant than previous quadrotors in the series. It features improved radio performance and more advanced sensors.
Bitcraze Crazyflie 2.1+	Crazyflie 2.1+ features an upgraded battery and propellers compared to the Crazyflie 2.1, and offers up to 15% improved flight performance
Bitcraze Crazyflie 2.1 Brushless	It has the longest flight time, the highest battery capacity, the largest payload capacity, and the heaviest quadrotor in the Crazyflie series.
3DR IRIS+	The first consumer drone capable of tracking its user
3DR Solo	The fastest quadrotor UAV with a speed of 24.72 m/s. It was developed to enable professional aerial photography and video shooting during flight

shows the prominent features of quadrotor UAV models according to the period in which they were produced.

Table 46. Selected technical specifications of quadrotor UAVs.

Model	Weight	Battery Capacity	Flight Time	Camera
Draganflyer V	454 g	1320 mAh	13–17 min	0.365 MP
Draganflyer X4-ES	2470 g	5400 mAh	20 min	20.2 MP
Draganflyer Commander	3750 g	6750 mAh	32 min	20.2 MP
Draganflyer Commander 2	3750 g	6750 mAh	32 min	24 MP
Draganflyer Commander 3 XL	15,000 g	16,000 mAh	50 min	24 MP
Parrot AR.Drone	420 g	1000 mAh	12 min	0.3 MP
Parrot AR.Drone 2.0	420 g	1500 mAh	12 min	0.9 MP
Parrot Bebop	400 g	1200 mAh	12 min	14 MP
Parrot Bebop 2	500 g	2700 mAh	25 min	14 MP
Parrot ANAFI	320 g	2700 mAh	25 min	21 MP
Parrot ANAFI USA	500 g	3400 mAh	32 min	21 MP
Parrot ANAFI Ai	898 g	3350 mAh	32 min	48 MP
DJI Phantom 1	670 g	2200 mAh	15 min	12 MP
DJI Phantom 2 Vision	1000 g	5200 mAh	25 min	14 MP
DJI Phantom 3	1216 g	4480 mAh	25 min	12 MP
DJI Phantom 4	1380 g	6000 mAh	28 min	12 MP
DJI Mavic 2 Pro	907 g	3850 mAh	31 min	20 MP
DJI Mavic 3	895 g	5000 mAh	46 min	20 MP
DJI Mavic 4 Pro	1063 g	6654 mAh	51 min	100 MP
DJI Agras T10	16,800 g	9500 mAh	120 min	12 MP
DJI Agras T25	32,000 g	15,500 mAh	198 min	12 MP
DJI Agras T70P	56,000 g	30,000 mAh	228 min	12 MP
Bitcraze Crazyflie 1.0	19 g	170 mAh	7 min	-
Bitcraze Crazyflie 2.0	27 g	240 mAh	7 min	-
Bitcraze Crazyflie 2.1	29 g	250 mAh	7 min	-
Bitcraze Crazyflie 2.1+	29 g	250 mAh	7 min	-
Bitcraze Crazyflie 2.1 Brushless	37 g	350 mAh	10 min	-
3DR IRIS+	1282 g	5100 mAh	16–22 min	12 MP
3DR Solo	1800 g	5200 mAh	20–25 min	12 MP

summarizes the selected technical specifications of the quadrotor UAVs presented in this section. Weights, battery capacities, flight times and camera resolutions of Quadrotor UAVs are given.

The graph showing the weights of the quadrotor UAV models is shown in Figure 40. The weights of quadrotor UAVs are in grams.

The graph of battery capacities for quadrotor UAV models is shown in Figure 41.

Figure 42 shows the average flight time graph of quadrotor UAV models.

Figure 43 shows the graph of camera resolutions for quadrotor UAV models. Crazyflie quadrotors do not have cameras, so they are not included in the graph.

Figure 40 shows that the weight of quadrotor UAV models produced by quadrotor manufacturers has increased over time. Increasing battery weights, improved hardware, and larger sizes of quadrotor UAVs have led to increased weight.

Figure 41 shows that the battery capacity of each manufacturer’s models has increased over time. This is closely related to the increasing weight of quadrotors and their more advanced hardware. Since increasing weight and improved hardware lead to increased energy consumption, an increase in battery capacity is normal.

The flight duration graph in Figure 42 shows that the flight duration of each manufacturer’s models has gradually increased over the years. The increased battery capacity of quadrotor UAVs has led to longer flight times. The increased flight duration of Draganfly’s quadrotor UAVs has facilitated search and rescue operations and allowed for the use of quadrotors for longer durations. An examination of DJI’s Agras T10, Agras T25, and Agras T70P quadrotors, produced for use in the agricultural sector, reveals increased flight duration over time. This increased flight duration allows for the spraying and fertilization of larger agricultural areas.

When the camera resolutions in Figure 43 are examined, it is observed that the camera resolutions of Draganfly quadrotors have increased. Because Draganfly quadrotors are widely used in search and rescue and mapping missions, the increased camera resolution allows the quadrotors to perform their missions more successfully. Parrot quadrotors are widely used by NATO armies. Due to the high military standards, Parrot quadrotors have a higher camera resolution than most other quadrotors. The DJI Mavic 4 Pro, on the other hand, has the highest camera resolution at 100MP, making it easier to use in photogrammetry and 3D mapping. Because the DJI Phantom series quadrotors and 3D Robotics quadrotors use GoPro HERO cameras, the camera resolution is the same across their models. Because the DJI Agras series is designed for agricultural spraying and fertilizing, it does not require a higher camera resolution. Therefore, the DJI Agras series quadrotors feature a 12MP camera.

5. Future Directions

The first manned quadrotors produced exhibited poor flight performance and were destroyed in accidents. Although quadrotors produced for the US military in the 1950s achieved successful flights, they were not mass-produced due to budget cuts and failure to meet military standards. Quadrotor prototypes produced for lifting heavy loads in the 1980s also suffered accidents. Starting in the 2010s, quadrotors began to be used as air taxis. The Chinese company Ehang has successfully mass-produced its autonomous passenger quadrotors. It is anticipated that the use of manned quadrotors as air taxis will become more widespread in the future. Thanks to developing technology, manned quadrotors will be able to carry more passengers and have longer ranges. With the development of autopilot software, manned quadrotors used as air taxis will take passengers to their destinations without a pilot. The proliferation of quadrotors used as air taxis will lead to increased noise pollution. The increasing use of quadrotors as air taxis will require new safety measures, regulation of urban air traffic, the implementation of necessary legal regulations, and the necessary certification processes for flight.

Quadrotor UAVs have gained widespread use thanks to advanced battery, hardware, software, and sensor technologies. Advanced sensors (especially optical flow sensors) and gimbal technologies will enable quadrotor UAVs to transmit more stable video in the future. Advancing 4G and 5G technologies allow quadrotors to transmit video and photos from kilometers away. 6G and beyond technologies will further increase maximum transmission distances. In this way, communication will be possible with quadrotor UAVs at much longer distances, and data transfer will be possible faster and in larger sizes. Communication infrastructure is often damaged during natural disasters. In the future, mobile base stations installed on quadrotor UAVs will be used to ensure rapid communication in natural disaster scenarios.

Developing lithium-ion battery technologies has extended the flight endurance of quadrotor UAVs. In the future, thanks to advancements in hydrogen fuel cell technologies, hydrogen fuel cell-powered quadrotor UAVs will be able to fly longer distances and lift heavier payloads than Li-ion battery-powered quadrotors. In the future, quadrotor UAVs are expected to be used in search and rescue operations at longer distances and with longer flight times. Developing thermal camera technologies facilitates search and rescue operations by detecting the body temperatures of searched individuals. Furthermore, thanks to the development of machine learning technologies, identifying and tracking wanted people and objects will become easier.

Quadrotor UAVs are increasingly being used in the agricultural sector. Thanks to developing artificial intelligence technologies, quadrotor UAVs will create optimal routes to spray and fertilize farmers’ fields. Machine learning technologies can detect pests on plant leaves and fruits. With the use of this technology, quadrotor UAVs used in the agricultural sector will be able to directly target pests on leaves and fruit, using fewer pesticides.

An increase in the number of cargo-carrying quadrotor UAVs is expected in the future. There will also be an increase in the number of quadrotor UAVs transporting organs between hospitals. It is also anticipated that quadrotor UAVs carrying first aid kits will be increasingly used in emergency response.

Autonomous drone swarms that can communicate with each other will facilitate coordinated search-and-rescue operations by scanning large areas. Autonomous drone swarms will facilitate coordinated transportation and coordinated pesticide spraying of agricultural areas. Advances in artificial intelligence, IoT, and edge computing will facilitate real-time on-site data processing and decentralized operation of quadrotors.

GPS signals can be weak or absent indoors, underground, and in urban canyons. In such cases, traditional GPS-based path planning methods are inapplicable. In the future, path planning will be based on real-time position information using a combination of inertial navigation systems (INSs) and visual simultaneous localization and mapping (SLAM). This will enable quadrotor UAVs to perform their missions without relying on GPS.

The rapid increase in the number of quadrotor UAVs could lead to cybersecurity and privacy issues. To prevent this, new laws and stricter oversight will be necessary in the future. Many countries have enacted laws prohibiting the flight of quadrotor UAVs over important public buildings and military bases. New laws are expected to be enacted in the future to restrict the flight of quadrotor UAVs to protect the privacy and security of private property belonging to citizens. The increasing number of quadrotor UAVs necessitates certification processes for their use. Quadrotor UAVs will be classified according to their size and intended use, and separate UAV pilot training will be provided for each class. This will ensure that both UAV pilots and the UAVs they operate are registered and potential security issues will be prevented.

6. Conclusions

This review article examines the developmental stages of quadrotors from the past to the present. Quadrotors are examined in two categories: manned quadrotors and quadrotor unmanned aerial vehicles. First, the developmental processes of manned quadrotors are described. The production process, technical specifications, photographs, and historical development of manned quadrotors are presented. In addition, the weight, powerplant, flight duration and passenger capacity data of manned quadrotor models were compiled into a table, and graphs were drawn based on this table. The first quadrotors produced can be characterized by poor stability, difficulty in control, short range, low speed, and limited altitude. Quadrotors produced for use by the US military in the 1950s yielded more successful results. However, their production was discontinued due to budget constraints and failure to meet military standards. Manned quadrotor prototypes produced for heavy-lifting in the 1980s were unsuccessful. The use of quadrotors as air taxis began in the 2010s. Manned quadrotors used for air taxis have achieved successful flights, and some have entered mass production. Furthermore, starting with the Ehanag 184, fossil fuel-powered quadrotors have been phased out and replaced by electric motors. The Ehang 184 manned quadrotor was the first air taxi to enter mass production.

The second stage describes the historical development, technical specifications, and areas of application of quadrotor unmanned aerial vehicles. Mass-produced and widely used quadrotor UAV models are discussed in detail. Graphs for the weight, battery capacity, flight duration, and camera resolution of the quadrotor UAV models are presented. Quadrotor UAVs began production in the late 1990s. The first quadrotor UAVs were used for hobby purposes. Later, these quadrotor UAVs, thanks to the addition of cameras, began to be used for photography and video recording. Technological advancements have led to the widespread use of quadrotor UAVs. Advances in battery technology allow for longer flights for all types of quadrotor UAVs. Advances in camera technology allow quadrotor UAVs to be used in various fields such as reconnaissance, surveillance, scientific research, wildlife monitoring, search and rescue, mapping, aerial photography and mineral exploration.

Increased battery capacities have enabled quadrotor UAVs, used in search and rescue and mapping, to operate for longer periods. Figure 42 demonstrates the increasing flight durations of quadrotor UAVs produced by Draganfly, Parrot, and DJI. The increasing camera resolution of quadrotor UAVs has enabled them to capture higher-quality images and perform search and rescue and mapping missions more successfully. Furthermore, advances in thermal camera technology have enabled quadrotor UAVs to locate sought-after creatures by detecting their body heat. Thanks to the development of 4G and 5G technologies, quadrotors can transmit images and videos from several kilometers away. Analyzing the tables presented in this article reveals that the range and transmission distance of quadrotor UAVs have increased. These advancements have facilitated the use of quadrotors in search and rescue operations, reconnaissance and surveillance, and mapping.

Advances in sensor and software technologies have enabled quadrotor UAVs to avoid obstacles, fly in flocks, and perform aggressive maneuvers. The capabilities of the Crazyflie series quadrotors, produced by Bitcraze and widely used by researchers, are examples of this development.

Advances in sensor and hardware technologies have increased the stable payload-carrying capacity of quadrotors. They also enable them to perform assigned missions by avoiding obstacles and following optimal trajectories. Today, many loads, such as first aid supplies and cargo, are transported stably by quadrotors. Agricultural spraying quadrotors can spray agricultural crops by calculating optimal trajectories and avoiding obstacles. The Agras series quadrotors produced by DJI have reached the capacity to carry increasing amounts of pesticides and fertilizers. The increased payload capacity of these quadrotors is clearly evident from the data obtained in the tables. The increased battery capacity of these quadrotors makes spraying large agricultural areas easier. Thanks to advanced sensor and camera technologies, they can perform spraying and fertilizing tasks by creating optimal routes and avoiding obstacles.

The Ardupilot and PX4 autopilot software used by quadrotor UAVs, as well as the Pixhawk flight cards, has been developed to work fully with PID controllers. While researchers have conducted theoretical studies and simulations on different controller designs, as discussed in this study, current quadrotor UAVs operate with PID controllers.

To sum up, this review article provided a detailed overview of the major manned quadrotors and quadrotor unmanned aerial vehicles produced from the early 1900s to the present. Their production stages, technical specifications, and areas of use were described, providing a comprehensive perspective for researchers focusing on this topic.