Vertical Take-off and Landing (VTOL) vehicle

Vertical Take-off and Landing (VTOL) Vehicles refer to the likes of aircraft that can take off, hover and land vertically such as most drones and helicopters. 

VTOL Designs 

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The early designs of VTOLs were based on rotorcraft designs, such as helicopters that incorporated the use of alternating horizontal rotors to provide lift. Since the inception of VTOLs many more designs have been introduced such as Cyclogyros, that generate lift from horizontal axis cyclic rotors; also classed as wing rotors, providing function like helicopters but also encompassing performance benefits of a fixed wing aircraft.

Another VTOL design consists of tilt rotors which generate lift by mounting horizontal rotors on shafts at the end of fixed wings to generate lift and propulsion. Certain military aircraft fit into the VTOL category, with the Harrier and F-35 perhaps being the most well known examples.

Some modern drones can also be classed as VTOLs, as they have the feature to take off and land vertically, and hover when there is not a suitable terrain to land. VTOL vehicles can be further electrified, hybridised, or powered by hydrogen fuel cells.  

Benefits of VTOL over conventional (CTOL) aircraft 

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VTOLs in comparison to conventional aircraft (CTOL) require no airstrip and less ground space to land, with most of them potentially able to land on open spaces, rooftops and grasslands. This provides many benefits for fast transport of goods and people, especially convenient in dense urban environments.

In terms of the need for special infrastructure, short-term solutions can involve using existing helipads (helicopter landing pads), car parks, shopping centres etc. However, there is a limitation to this as VTOLs would not be able to operate solely relying on take-off and landing in populated areas such as Hyde Park in London.

This is partially due to the number of people sharing that space and associated risks with operations in close proximity to areas of mass gatherings; but also due to the aircraft’s need for specialist charging infrastructure, maintenance and repair facilities, passenger hubs etc.

Upon mass-scale implementation, with added levels of complexity will come the necessity to have a full physical and digital infrastructure in place to enable  safe and effective operations.

Traditional VTOLs in the past (such as helicopters) have been used for many operations as part of search and rescue, medical evacuations, air ambulances, and defence usage, whereas drone implementation for such operations have only recently begun.

VTOLs being developed by the industry for Advanced/Urban Air Mobility have not yet been implemented globally, although there are significant developments being made, by, for example, EHang and Volocopter. These vehicle manufacturers are looking to use their eVTOLs for aerial fire fighting and medical rescue services amongst other use cases.

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Sources and suggested reading:

1. VTOL: how does vertical take-off and landing technology work - Wired 

2. A Brief History of Vertical Take-Off and Landing - Popular Mechanics

3. Urban Air Mobility - The rise of a new mode of transportation - Roland Berger

4. Aviation Management: Global Perspectives. p. 133. ISBN 9789380228396 - Khurana KC (2009). 

5. Vertical Take Off and Landing (VTOL) Aircraft with Vectored Thrust for Control and Continuously Variable Pitch Attitude in Hover - NASA

6. City Airbus - Airbus

7. The world's first hydrogen-fuel cell powered air mobility vehicle - Skai 

8. Cyclogyro rotors - CycloTech

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