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What is a VTOL Drone & How do VTOL Drones Work?

Are you eager to know what VTOL drones are, how they function, and how they manage to take off, land, or fly in almost any environment?

VTOL is the short form of Vertical Take-Off and Landing. As the name suggests, a VTOL drone can take off, hover around, and land vertically virtually anywhere without depending on runways.

These drones help with mapping, surveying, research, environmental monitoring, and surveillance, among other uses.

Here is everything you need to know about VTOL drones, what they are used for, how they work, and more.

How do VTOL drones operate?

The way VTOL drones work depends on their qualities and features – propulsion method, flight mode, and design.

That said, VTOL drones have varying qualities and features and are made for specific operations in commercial, consumer, governmental or institutional markets.

An example of a VTOL aircraft is a helicopter or an F35B fighter jet, which can take off and land from the back of an aircraft carrier.

VTOL drones function the same way as these aerial vehicles.

The taking-off methods may determine how VTOL drones work because some VTOL drones use short take-off and landing (STOL), while others employ a conventional take-off and landing (CTOL) mode of flight.

Other VTOL drones use the short take-off and vertical landing (STOVL) flight mode.

For design, there are rotorcraft and power lift VTOL drone designs. You may find some VTOL drones taking off with the aircraft’s nose on top of the surface (face up).

Regarding the propulsion system, VTOL drones use different propelling methods like lithium batteries, solar energy, hydrogen fuel cells, and gasoline. However, some drones can use two power sources in one flight.

Note: Hybrid VTOL drones work differently.

What are hybrid VTOL drones?

Hybrid VTOL drones are drones that can employ two different components, such as fixed wings and vertical rotors.

The VTOL fixed-wing drone is especially flexible for many military aerial and commercial applications.

What are the types of VTOL drones?

There are various ways of categorizing VTOL drones. However, the most common classification depends on the following (just like how they work):

  • Design
  • Mode of flight
  • Method of propulsion

1. VTOL drone types according to design

There are two main types of VTOL drones according to design, namely:

  • Rotorcraft drones
  • Power lift drones

a. Rotorcraft drones

These are drones that use propellers for propelling themselves. The propellers are usually connected to the motors.

Rotorcraft drones are very efficient in applications that may require a quick response. This is because they can reach areas that fixed-wing drones cannot reach.

The four main types of rotorcraft drones include:

  • Single rotor helicopters
  • Autogyro/gyrocopters/gyroplanes
  • Gyrodyne/compound gyroplanes/compound helicopters
  • Cyclogyro/cyclocopter
Single rotor helicopters

These are VTOL drones with both a primary and a small rotor at the tail. They have the ability to fly onward, backward, laterally, or vertically.

Single rotor helicopters can fly in an area for a longer time. It can also take off and land in dangerous places where conventional fixed-wing drones cannot.

Autogyro/gyrocopters/gyroplanes

An autogyro aircraft is also known as the gyrocopter or the gyroplane. It employs a rotor with no power that whirls in free autorotation from airflow and a convenient power source to generate a thrust onward.

The aircraft has the ability of STOL and CTOL except for the VTOL.

They usually look like single rotor helicopters but cannot fly in all areas. Unlike conventional helicopters, autogyro aircraft are always unpowered.

Gyrodyne/compound gyroplanes/compound helicopters

Gyrodyne, commonly known as the compound gyroplanes or compound helicopters, have a powered main rotor which they use in taking off and landing only.

They also have a different source of power like propellers and a jet engine that aids the thrust onward.

These drones can also have stubbed wings for additional lift. During the take-off period, the gyrodyne aircraft depends on the system that provides the onward thrust. This occurs when the main rotor with no power revolves in a free autorotation.

They are also capable of VTOL, CTOL, and STOL.

Cyclogyro/cyclocopter

Cyclogyro, also known as cyclocopters, employ cyclorotors on the horizontal axis.  The rotation of the cyclorotors provides both single and fixed-wing rotor benefits to the aircraft. The cyclorotors also generate the aircraft’s propulsion and lift.

The configuration, however, has not yet been effective in drones as they are only available in manned aircraft.

They are capable of VTOL, CTOL, and STOL.

b. Power lift drones

Power lift is usually employed in manned aircraft. Many drones do not use the power lift drone design. The three various types of powered lift aircraft are:

  • Tail-sitter drones
  • Convertiplane aircraft
  • Thrust vector control aircraft (TVC)
Tail-sitter drones

These are drones that are only capable of taking off vertically. This is because they are placed at the same point as the rocket available on the tail.

Tail-sitter drones usually employ rocket engines or prop-rotors to aid in propulsion.

Tail-sitter hybrid VTOL drones take off vertically and spin using duplicate rotors. The rotors enable them to take off, hover, and fly onwards.

They will arrive at a horizontal point and proceed with their flight horizontally until they come to land vertically.

The method is always known as the vertical take-off and landing (VTOL). In the case of a powered rocket, it would be known as the vertical take-off and vertical landing (VTVL).

Propellers, rockets, and other propulsion means can effectively power tail-sitter aircraft.

Convertiplane aircraft 

These are manned VTOL aircraft with wings, i.e., hybrid VTOL.

In convertiplane aircraft, the prop-rotors spin airfoils that replace the airplane wings and the propeller blades to provide lift for the aircraft.

Convertiplane aircraft are available in four primary forms, namely:

  • Tiltrotor aircraft
  • Tilting ducted fan aircraft
  • Tiltwing aircraft
  • Multi-rotor fixed wing or Quadplane drones

The Tiltwing, Tilting, and Tilrotor fan aircraft, which are ducted, utilize prop-rotors to operate.

Most of the multi-rotor fixed-wings employ prop-rotors, except others that use different propulsion systems for horizontal and vertical flights.

Tiltrotor aircraft

A tiltrotor is capable of taking off vertically. This is because they have a technique that allows their propellers connected to every rotor to place themselves vertically when taking off or landing horizontally, evolving into a wing-born flight.

The spinning propellers are usually connected at the two fixed wings end, hence known as the hybrid VTOL drones.

Tiltrotor aircraft can also use conventional methods like short or long runways for taking off.

Tiltrotor aircraft can operate the VTOL, STOL, CTOL, and STOVL flight modes. Also, various quadplanes use the tiltrotor method for forward flight transitioning.

Tilting ducted fan aircraft

These are aircraft that have the same working principle as the tiltrotor. However, they use ducted fans as a propulsion mode.

Tiltwing aircraft

They are aircraft that can vertically take off since they can tilt their wings containing rotors connected to them. They can also evolve into wing-born flight forward by horizontally tilting the wings when flying.

Tiltwing aircraft can employ conventional techniques like the long or short runways to take off.

They are also suitable for VTOL, STOL, CTOL, and STOVL flight modes.

Multi-rotor fixed wing/Quadplane drones

They are drones that are capable of taking off both horizontally and vertically. And are sometimes known as hybrid VTOL drones.

Multi-rotor aircraft look like fixed-wing drones. This is because of the presence of wings that resemble an airplane. However, they may have more arms or specific place that contains propeller blades essential for the vertical take-off.

Multi-rotor drones can use vertical taking off and land (VTOL). Although a few can employ short take-off and landing (STOL), conventional take-off and landing (CTOL), and short take-off and vertical landing (STOVL).

Thrust vector control aircraft (TVC)

Thrust vector control refers to the capability of an aircraft to control the direction of thrust produced in the jet engine or rocket. It helps in the vertical and horizontal propulsion and hovering of the aircraft in a specific place.

TVC is usually essential for changing the direction of both aircraft and missiles.

TVC is always used by a jet-propelled vehicle known as a tiltjet aircraft. The aircraft is operated using jet engines only and not rocket engines. 

Currently, the tiltjet aircraft can only be essential in manned aircraft. The drone is the same as the tiltrotor aircraft. However, unlike tiltrotor aircraft, it operates using turbojet engines other than propellers for propulsion.

2. VTOL drone types according to the mode of flight

Flight modes are the various methods used by various aircraft to take off. There are different VTOL aircraft that can employ many modes of flight.

The modes of flight are as follows:

  • Short take-off and landing (STOL)
  • Conventional take-off and landing (CTOL)
  • Short take-off and vertical landing (STOVL)
  • Vertical take-off and vertical landing (VTVL)
  • Vertical or short take-off and landing (V/STOL)

a. Short take-off and landing (STOL) aircraft

They are usually like CTOL aircraft, except for needing a shorter runway for taking off and landing. You can find this flight mode commonly on runways that lack space, i.e., in remote areas with insufficient space for a long runway.

b. Conventional take-off and landing (CTOL) aircraft 

These are also called horizontal take-off and landing (HTOL) aircraft.

CTOL aircraft use conventional methods like full runways to take off. Such aircraft are hybrid VTOL and standard fixed-wing aircraft.

c. Short take-off and vertical landing (STOVL) aircraft

These aircraft take off by employing short runways to enhance vertical landing. STVOL aircraft are capable of vertically taking off. However, they do not do so because of their heavy payload. 

The main difference between STOVL  and V/STOL aircraft is that V/STOL can take off vertically or from short runways while some STOVL aircraft cannot.

d. Vertical take-off and vertical landing (VTVL) aircraft

These are aircraft that can take off and land vertically. The only distinctive feature between VTVL and VTOL aircraft is that VTVL can only get power through rockets. Hence, the name rocket-powered aircraft.

Examples are ballistic missiles and rockets that are operated or controlled remotely.

e. Vertical or short take-off and landing (V/STOL) aircraft

These usually can take off and land both from short runways or vertically.

The difference between V/STOL and VSTOL aircraft is that V/STOL can use conventional methods to take off. Like on short or long runways.

3. VTOL drone types according to the method of propulsion

The VTOL drones have three basic methods of propulsion, namely:

  • Propulsion by engine
  • Propulsion by motor
  • Propulsion by a hybrid engine 

a. Propulsion by an engine

The various types of engines include:

  • Piston/reciprocating engines
  • Gas/combustion turbine engines
  • Rotary engines
Piston/reciprocating engines

These are engines that use pistons to transform pressure into a rotating movement.

Gas/combustion turbine engines

They are also known as jet propulsion. Gas engines usually utilize the pressure from the exploding fuel to enhance turbine movement and generate thrust.

Examples of such engines are turboprop, turbofan, turboshaft, and turbojet engines.

Rotary engines

Examples include gasoline, Wankel, and diesel engines. The working principle entails the movement of a rotor inside the engine from a single chamber to the other that makes it contract and expand the gas.

b. Propulsion by motor

The various types of motors available are:

  • Solar-powered motors: They power themselves using energy, hence do not require a battery.
  • Hybrid motors: They can utilize many different energy types like fuel. They are usually powered by electricity and other fossil fuels.
  • Battery-powered motors: Are fuelled by many power source types like hydrogen fuel cells, Nickel-metal hydride cells, and Lithium-polymer.

c. Propulsion by a hybrid engine

Hybrid engines are engines that utilize electricity and gas. For instance, they can use gasoline or diesel with a battery-powered electric motor.

What are VTOL drones used for?

The VTOL drones are essential in many different applications, such as:

  • Researching and monitoring the environment: VTOL drones can help in determining the operations of windy conditions in various areas.
  • Surveying and mapping: You can use VTOL drones to survey areas larger than 500 hectares. This is because they are more versatile and can maneuver.
  • Inspection and surveillance: VTOL drones can steadily hover in place and take high-quality footage required for conducting surveys by professionals. For this reason, they are commonly used in inspecting crop surveys, power lines, and pipelines.
  • Mining and Agriculture: VTOL drones help improve mining and agricultural operations through surveys.
  • Construction: VTOL drones are used in the construction industry, especially in places with less space for launching and landing fixed-wing platforms.

Advantages of VTOL drones

Some of the advantages of VTOL drones include:

  • VTOL drones require minimal horizontal space to launch, unlike fixed-wing aircraft. This is because VTOL drones can vertically take off, thus doing away with the runway requirement.
  • They can efficiently maneuver since they have the capability of making quick spins in all directions and can hover in a place. VTOL drones are commonly used in specific commercial operations other than fixed-wing.
  • VTOL drones can capture results within the shortest time possible compared to multi-rotor drones due to their speed—this helps in conserving time for every project.
  • All VTOL drones can take off and land in areas with heavy wind.
  • VTOL drones are capable of tilting to a specific level. This helps compensate for the wind, thus enabling the maximum stability and safety of the aircraft during landing and taking off time.
  • All VTOL drone types transitioning into horizontal wing-born flight have more fuel efficiency than regular helicopters.
  • Hybrid VTOL drones use multiple flight modes to transition and employ vertical and horizontal flights. This, in turn, generates the possibility of experimenting with different operations by professionals and consumers.

Disadvantages of VTOL drones

Other than the advantages, VTOL drones also have some disadvantages, as mentioned below:

  • VTOL drones are usually expensive and complex to use. For instance, you may require more parts and technology, i.e., more actuators for the quadplanes to enhance the transitioning between vertical and horizontal flight. They also have high maintenance costs compared to regular fixed-wing drones.
  • VTOL drones can easily break since it has one small bump in the rotor tail that can lead to the crashing of the whole system. Also, the system may malfunction if not properly taken care of.
  • It is usually dangerous for the hybrid VTOL drones to transition from vertical to horizontal flight mode.
  • Unlike fixed-wing drones, VTOL drones contain fewer payload capacities and can’t endure environmental changes.
  • In vertical flight modes, VTOL drones are usually vulnerable to heavy wind that may hinder their operations. This may lead to a significant reduction of flight time as well as drone emplacement.

Conclusion

Professionals and researchers are developing VTOL drone technology for commercial transportation applications.

Its popularity may snowball because many people are exploring it and, so far, have had positive results in their operations.