Recently, the surge in the interests in unmanned aerial vehicles has soared dra-matically worldwide due to many potential benefits foreseen by this technology. The most widespread use of the commercial drones is a multi-copter form of unmanned aerial vehicle, because of its vertical takeoff and landing (VTOL) capability. However, due to the structural characteristics, it has a disadvantage that the flight time is quite short, which is typically ranging between 15 to 30 minutes. The fixed wing type of unmanned aerial vehicles has a longer flight time and duration, but it is not easy to secure a safe landing space, especially in the city areas. For this reason, demand for vertical fixed take-off and landing aircraft is rapidly increasing throughout the world. This study analyzes the trends and recent development of global VTOL technology and provides a direction into which the current state of the technology should be heading. By comparing the advantage and disadvantage of various VTOP propulsion types, we can clearly identify the most effective form of VTOL propulsion types. Such analysis will be highly beneficial to the drone researchers and scientists in terms of future development.
One can clearly see the recent surge and wide applications of unmanned aerial vehicles in many areas, such as agriculture, forestry, surveillance, rescue operations, security, aerial photographing, and so on. The most widespread use of the commercial drones is a multi-copter type of unmanned aerial vehicle. For example, most aerial photography drones are this type. It is because this type of drones doesn’t require a length runway and it can hover in the air while filming. This kind of convenience is necessary, especially in the congested areas like city centers. However, it has a disadvantage that the flight time is too short (typically ranging between 15 to 30 minutes). The fixed wing type drones can stay afloat for a much longer time, typically over 1 or 2 hours. However, it is not always easy to find a safe landing space, and it is not easy to manually control this type of drones [
The third type of unmanned aerial vehicle is often referred to as a VTOL drone, which can vertically takeoff and land, while flies like a fixed-wing aircraft once airborne. It doesn’t require a runway, and land like a helicopter. The VTOL drone can hover in the air, yet capable of flying a much longer time. Due to these advantages, the VTOL drone is taking a great interest among researchers and commercial applications. In order for VTOL drones to hover and make a transit flight like airplane, its propulsion system should be very different than those of multi-copter type drone or fixed-wing type drones. Our initial analysis shows that there are so many varieties already developed, while a thorough study of analyzing VTOL types is not present until this time. In this regard, our goal is to collect the different types of VTOL propulsion technologies and analyze the advantages and disadvantages of each type. Such study will provide valuable insights for the drone community.
The analysis classifies each type of VTOL into 3 categories. This include: 1) TYPE1, which has a wing and a TILT-ROTOR, 2) TYPE 2, with no wings and similar to helicopters, and 3) TYPE 3 with wings and no tilting mechanism functions. The details are defined in
Tables 2-5 show the specifications of VTOL drones in major countries. In fact, there are over 35 VTOL drones we have identified. Due to similarities, in this paper, we only show the representative types of VTOL drones. Those are illustrated in the tables below.
First, the percentage of VTOL types has been investigated, as shown in
TYPE1 | TYPE2 | TYPE3 | |
---|---|---|---|
Wing | O | X | O |
Tilt Rotor | O | X | X |
VTOL | O | O | O |
Contents | Picture | Picture |
---|---|---|
TYPE1 | ||
Name | TR-100 | Sky Prowler |
Manufacturer | KARI | Krossblade Aerospace |
Country | South Korea | USA |
Length | 5.0 m | 0.5 m |
Payload | 100 kg | 0.5 kg |
Flying time | 5 hrs | 1 hrs |
propellant | Gasoline | Motor |
Max speed | 500 km/h | 100 km/h |
TYPE1 | ||
Name | JOBY S2 | JOBY LOTUS |
Manufacturer | JOBY AVIATION | JOBY AVIATION |
Country | USA | USA |
Length | N/A | N/A |
Payload | 176 kg | 27 kg |
Flying time | 15 hrs | 1 hrs |
propellant | Gasoline electric hybrid | Gasoline electric hybrid |
Max speed | 200 km/h | 185 km/h |
Contents | Picture | Picture |
---|---|---|
TYPE2 | ||
Name | DTI RTN KSM 150 | APID 60 |
Manufacturer | N/A | TOP Engineering |
Location | Taiwan | Taiwan |
Length | 2.1 m | 4.0 m |
Payload | 15 kg | 55 kg |
Flying time | 2.5 hrs | 5 hrs |
propellant | Gasoline | Gasoline |
Max speed | 100 km/h | 110 km/h |
TYPE2 | ||
Name | Navig 8 Gas | Navig 8 Electric |
Manufacturer | 4FRONT ROBOTICS | 4FRONT ROBOTICS |
Country | Canada | Canada |
Length | 3.1 m | 1.64 m |
Width | 2.9 m | 1.0 m |
Payload | 31 kg | 4 kg |
Flying time | 2.5 hrs | 1 hrs |
propellant | Gasoline | MOTOR |
Max speed | 200 km/h | 83 km/h |
Contents | Picture | Picture |
---|---|---|
TYPE3 | ||
Name | SR-1 | ARCTURUS JUMP-20 |
Manufacturer | CQV | ARCTURUS |
Country | Japan | USA |
Length | 1.7 m | 2.9 m |
Payload | 0.7 kg | 27 kg |
Flying time | 0.5 hrs | 9 hrs |
propellant | MOTOR | Gasoline |
Max speed | 55 km/h | 133 km/h |
TYPE3 | ||
Name | V-Bat | Current MK1 |
Manufacturer | MARTIN UAV | Current MK1 (MK2) |
Country | USA | USA |
Length | 2.4 m | 2.0 m |
Payload | 2 kg | 18.5 kg |
Flying time | 8 hrs | 15 hrs |
propellant | Gasoline | Gasoline |
Max speed | 350 km/h | 148 km/h |
similar in terms of numbers among the drone that we have investigated. Each type bears specific merits and also disadvantages, so each type takes about the same percentages. Second, we have analyzed each type according to the number of criteria investigated. The results are organized in
By analyzing the content of the payload specification, the larger the size of the airframe, the more likely it was to see the airframe size increase. It appears to affect the flight time with drag on airframe, depending on whether or not the airframe is aerodynamically well balanced. Third, we have classified the VTOL drone in accordance with their size and payload. It appears that the size and payload will continue to increase in the future.
The analysis shows that the higher the payload, the bigger the size of the aircraft.
VTOL TYPE | Model | Engine Type | Flying Time | |||||
---|---|---|---|---|---|---|---|---|
Motor | Gasoline | Diesel | Hybrid | 2 Hr↓ | 4 Hr↓ | 4Hr↑ | ||
TYPE 1 | FE-Panther | O | - | - | - | |||
KUS-TR (TR-60) | O | O | ||||||
TR-100 | O | O | ||||||
Sky Prowler | O | O | ||||||
JOBY S2 | O | O | ||||||
JOBY LOTUS | O | - | - | - | ||||
TYPE 2 | Air Mule | O | - | - | - | |||
Airbus DS Tanan 300 | O | - | - | - | ||||
HEF32 | O | O | ||||||
VSR700 | O | O | ||||||
DTI RTN KSM 150 | O | O | ||||||
APID 60 | O | O | ||||||
Navig 8 Gas | O | O | ||||||
Navig 8 Electric | O | O | ||||||
DP-6XT WHISPER | O | O | ||||||
UAV IT180-120 | O | O | ||||||
DP-12 RHINO | O | O | ||||||
DP-14 HAWK | O | O | ||||||
TYPE 3 | Aerosense | O | O | |||||
Wingtra | - | - | - | - | - | - | - | |
VD 200 | - | - | - | - | O | |||
X-Plane | O | - | - | - | ||||
SR-1 | O | O | ||||||
ARCTURUS JUMP-20 | O | O | ||||||
V-Bat | O | O | ||||||
Current MK1 (MK2) | O | O | ||||||
FALCON-V | O | O | ||||||
PIGEON-V | O | O | ||||||
JOUAV CW-20 | O | O | ||||||
FOXY pro | O | O |
VTOL TYPE | Model | Payload | Wing Span | ||||
---|---|---|---|---|---|---|---|
10 Kg↓ | 20 Kg↓ | 20 Kg↑ | 2 m↓ | 5 m↓ | 5 m↑ | ||
TYPE1 | FE-Panther | O | O | ||||
KUS-TR (TR-60) | O | O | |||||
TR-100 | O | O | |||||
Sky Prowler | O | O | |||||
JOBY S2 | O | O | |||||
JOBY LOTUS | O | O | |||||
TYPE2 | Air Mule | O | O | ||||
Airbus DS Tanan 300 | O | O | |||||
HEF 32 | O | O | |||||
VSR 700 | O | O | |||||
DTI RTN KSM 150 | O | O | |||||
APID 60 | O | O | |||||
Navig 8 Gas | O | O | |||||
Navig8 Electric | O | O | |||||
DP-6XT WHISPER | O | O | |||||
DP-5X WASP | O | - | - | - | |||
UAV IT180-120 | O | O | |||||
DP-12 RHINO | O | O | |||||
DP-14 HAWK | O | O | |||||
TYPE3 | Aerosense | O | O | ||||
Wingtra | O | - | - | - | |||
VD 200 | O | O | |||||
X-Plane | O | O | |||||
SR-1 | O | O | |||||
ARCTURUS JUMP-20 | O | O | |||||
V-Bat | O | O | |||||
Current MK1 (MK2) | O | O | |||||
FALCON-V | O | O | |||||
PIGEON-V | O | O | |||||
JOUAV CW-20 | O | O | |||||
FOXY pro | O | O | |||||
JOUAV CW-10 | O | O |
It is more likely that a bigger air frame affects the flight time. For drones that use electric motors, the battery capacity is directly related to the flight time. However, a bigger battery size inversely affects the payload capacity. According to the analysis of three types, it appears that the fixed wing type VTOL drones with no tilting mechanism are getting more and more popular. It is due to the facts that this type of VTOL drone can provide a stable transit flight while reducing the complexity associated with tilting mechanism. So the drones can be built at a lower cost and a lot lighter. It is judged that the surge in global demand for a wide range of VTOL drone is expected, and a growing competition is expected around the world.
This work was supported by the Ajou University research fund.
Jo, D. and Kwon, Y.J. (2017) Analysis of VTOL UAV Propellant Technology. Journal of Computer and Communications, 5, 76-82. https://doi.org/10.4236/jcc.2017.57008