A vertical takeoff and landing (VTOL) aircraft is a vehicle that can depart, hover and land vertically. This includes fixed-wing aircrafts with the ability to take off and touch down vertically as well as helicopters or other aircraft with powered rotors.
VTOL aircrafts' ability to take off and land vertically as well as hover, fly slowly and land in small spaces distinguishes it from the conventional aircraft. Also, the most recent VTOL aircrafts in development use electric motors or batteries instead of fuel, designating them electric vertical takeoff and landing (eVTOL) aircrafts.
How VTOL aircrafts work
There are currently two different types of VTOL technology: rotary wing aircraft and powered-lift.
A rotary wing aircraft (or rotorcraft) uses lift created by rotor blades spinning around a central mast. Some examples of rotorcrafts are:
- Helicopter – The helicopter's spinning rotors create thrust like a large propeller that is directed vertically, enabling it to lift off. While in flight, a slight tilt in the desired direction pushes some of the aircraft's thrust and sends the craft forward.
- Gyrodyne - The gyrodyne is also known as a compound helicopter because it has the powered rotor of a helicopter, but a separate forward thrust system
- Cyclogyro - On the cyclogyro, the rotary wing's axis and surfaces remain sideways across the airflow, similar to a conventional wing.
Powered-lift aircraft takeoff and land vertically but behave differently than rotorcrafts while in flight. They often have a fixed-wing design. Some examples of powered-lift aircraft are:
- Convertiplane - The convertiplane relies on the rotor for lift when taking-off, but then switches to a fixed-wing lift while in flight.
- Tiltrotor - The tiltrotor, also known as a proprotor, moves its propellers or rotors vertical to achieve VTOL and then tilts them forwards while flying for horizontal wing-borne flight; the main wing remains fixed in place.
- Tailsitter - The tailsitter aircraft sits vertically for takeoff and landing, but, once in the air, the whole craft tilts forward to achieve horizontal flight.
Most powered-lift aircrafts today are vertical and/or short takeoff and landing (V/STOL) vehicles. If possible, the aircrafts prefer to make rolling takeoffs from a runway since it requires less thrust, and significantly increases takeoff weight, range or amount of weight the craft can carry (payload).
In addition to operating in V/STOL, some VTOL aircrafts can switch to conventional takeoff and landing (CTL) or slow takeoff and landing (STOL). However, many helicopters can only operate in VTOL due to the lack of landing gear that can handle horizontal movement.
Benefits of VTOL
Since the recent eVTOL aircrafts use batteries or electric motors instead of fuel, they generate a huge reduction in the cost of maintenance and fuel which leads to lower overall costs. The electric motors are also more energy efficient than jet engines and would reduce noise pollution and gas emission.
VTOL technology also allows vehicles to land almost anywhere. This makes VTOL aircrafts more flexible and, therefore, able to perform actions that are impossible for conventional planes. This flexibility creates a major advantage for aircrafts in combat or rescue situations.
Since takeoff and landing are not controlled by the wing of a VTOL aircraft, then the vehicle can be built in such a way that the wings are optimized for speed and efficiency. This construction can also help reduce the drag experienced by the aircraft, making it even faster.
History of VTOL
The idea of vertical flight was first seen thousands of years ago in Leonardo da Vinci's sketchbook. He drafted an image of what would become the helicopter. The prototype for the first helicopter took flight in 1907 but was not perfected until after World War II.
In addition to the helicopter, other VTOL aircraft approaches were attempted between 1920 and 1930. Between 1922 and 1925, Henry Berliner experimented with a horizontal rotor fixed-wing aircraft. In 1928 and 1930, Nikola Tesla and George Lehberger received patents for somewhat impractical VTOL fixed-wing aircraft with tilting engines. Leslie Everett Baynes received a patent in the late 1930s for the Baynes Heliplane, another tilt rotor aircraft.
From the 1940s until today, over forty V/STOL aircraft have been tested, but only four have actually made it to production. The four successes include: the British Harrier "jump jet" and its descendants, the Soviet An-72/74 transport aircraft, the Soviet Yak-38 naval fighter and the Bell/Boeing V-22 Osprey. The V-22 Osprey is considered the world's first production tiltrotor aircraft.
Throughout the 1960s, attempts were made to build a commercial passenger aircraft with VTOL abilities, but none successfully made it to production. All prototypes were dismissed as too heavy and expensive to operate.
Between 1964 and 1972, Canadair manufactured a V/STOL turbine tilt-wing monoplane -- an airplane with only one wing -- called the CL-84. Three updated versions were ordered by the Canadian government for military evaluation. These planes were named CL-84-1. Between 1972 and 1974, the CL-84-1 was shown to and evaluated by the U.S. aboard the aircraft carriers USS Guam and USS Guadalcanal as well as other locations. Unfortunately, two of the CL-84s experienced mechanical failures and crashed during testing and production contracts were never granted.
In the 1960s and early 1970s, Germany also planned to produce three VTOL aircrafts. Two models were built, but the project was cancelled due to high costs and political problems.
Future of VTOL aircrafts
As a response to the rapid acceleration of action and investment in VTOL, many traditional and new aerospace companies have started working to build capable new aircraft. A number of these companies predict fully automated flight in the future. However, they also recognize that a human pilot is still necessary either in the craft or at a control center until the automated systems are stronger.
In 2014, testing began on the BlackFly VTOL aircraft, a lightweight, electric, personal aerial vehicle (PAV) from the company Opener. BlackFly was first displayed at the 2018 EAA AirVenture Convention in Oshkosh, Wisconsin. It is the first fixed-wing eVTOL aircraft in the world. BlackFly introduces the reality of a new era of three dimensional personal transportation.
Lilium, a Munich-based aviation startup, hopes to offer an on demand flying taxi service, claiming it will be five times faster than driving. The prototype they have developed has two seats and is shaped like a conventional airplane but uses a VTOL system.
The uberAir project, from multinational transportation network company Uber, has pledged to launch its first flying taxis using VTOL in 2020.
While the future looks bright for VTOL, there are still huge amounts of technical challenges on both the aircraft and infrastructure side as well as regulatory hurdles for the design and operations of the aircraft.
Examples of VTOL aircrafts seen today
In the civilian sector, helicopters are the only VTOL craft in use. However, many other VTOL vehicles are being developed, like BlackFly and Lilium's on demand flying taxis. VTOL aircrafts are more common in military service. The helicopter is used as well as the Bell Boeing V-22 Osprey and aircrafts using directed jet thrust, like the British Harrier crafts.
Recently, drones have become increasingly popular, providing both commercial and military use. Most drones utilize VTOL technology and companies all over the world are working to create the best vehicle. Drone photography has become a hobby for consumers with store bought drones as well as a service offered by a variety of companies. Drones are also being developed by Amazon Prime as a potential delivery method.