City buildings could blow air taxi future off course

City buildings could blow air taxi future off course

Air taxis are coming to our cities, but a new study warns regulations will need to address dangerous wind gusts around city buildings and other urban infrastructure.

The air taxi market is almost ready for take off, with companies such as Boeing, Hyundai, Airbus and Toyota building fleets to have commuters flitting through the sky. 

Europe and the US have both drafted new rules to pave the way for air taxis to begin operations within the decade, with Australia’s Civil Aviation Safety Authority (CASA) to follow suit.

A new study by the RMIT Uncrewed Aircraft Systems (UAS) Research Team has measured how sudden wind gusts form around city buildings significantly affect the flight of small aircraft. 

The team says this is a danger that has not yet been adequately addressed by draft regulation in Australia or overseas. 

Strong wind gusts form around city buildings

Small aircraft are at risk from wind gusts because they land and take off at low speed. The RMIT researchers found sudden wind gusts can pose significant safety challenges for air taxis and drones in under a second.

Lead researcher and aerospace engineer, Dr Abdulghani Mohamed, said air taxis and drones would need more power for landing or taking off in cities compared with an airport or an open space, for example. 

“These aircraft will need propellors equipped to respond rapidly and at high power to quickly force the vehicle back on-course,” said Dr Mohamed from the School of Engineering. 

Lead researcher on the RMIT study, Dr Abdulghani Mohamed. Lead researcher on the RMIT study, Dr Abdulghani Mohamed.

Making our city skies safe

Regulations for Advanced Air Mobility (AAM) aircraft, such as future air taxis, are being drafted around the world, including the US and Europe.

The RMIT team warns frameworks are desperately needed to ensure this new technology is safe and reliable, especially when it operates autonomously.

“Current regulations and certification do not specifically address safe autonomous operation when traversing building flow fields,” Mohamed said. 

He argues that site-specific wind simulations and measurements are essential to identify hazardous regions. 

“As we determine the location of vertiports – where these vehicles will take off and land – we also need to determine hazardous regions to avoid. This will enhance safety and reduce interruption of a fleet due to wind conditions,” Mohamed said.

“Using state of the art sensors, we can sense the turbulence in real-time and distribute this information to both the vertiport operator and the incoming and outgoing aircraft for safer and more informed landing and take off operation.”

“The margin of error will be much lower than at airports, where larger aircraft can tolerate much stronger gusts. We won’t have that flexibility with air taxis in cities.”

Co-author Dr Matthew Marino said purpose-built vertiports should allow us to integrate design features to reduce hazardous conditions from occurring.

 “Existing buildings can also be repurposed as vertiports, however may require modifications to improve the aerodynamics near the landing pads. The effectiveness of such design features must be assessed through either small-scale experiments using wind tunnels and or full-scale measurements,” he said.

“Extensive wind flow mapping at full-scale will no longer be daunting in the future. We are continuing to develop our wind sensing drones – a swarm of drones instrumented with wind anemometers – to accurately map around large infrastructure.”

He also advises urban aircraft should be certified to handle strong gusts and turbulence around buildings, which will impact manufacturers.

Next steps 

These recommendations could help shape the regulation of vertiports, flight paths and air taxi requirements in Australia and globally.

The researchers are continuing research into wind gusts around buildings, with further exploration of different building shapes that may minimise adverse effects. They are also studying the sensitivity of vehicles to gusts and turbulence, as well as flight-stability technologies.

‘Gusts Encountered by Flying Vehicles in Proximity to Buildings’ is published in MDPI (DOI: 10.3390/drones7010022).

This research was conducted in collaboration with the University of Maryland and Lehigh University, and was funded by the US Airforce Office for Scientific Research and DSI Group. 


Story: Sarah Gates

27 March 2023


27 March 2023


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  • Aerospace & Aviation
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