City buildings can blow air taxis off course

The air taxi industry is on the verge of taking flight as major companies like Boeing, Hyundai, Airbus, and Toyota are actively developing fleets to facilitate seamless commuting in the skies. Both Europe and the US have formulated new regulations to establish a framework for air taxi operations to commence within the next decade. Australia’s Civil Aviation Safety Authority (CASA) is also expected to adopt similar measures in due course.

In recent years, there has been a significant advancement in conducting intricate studies on the impact of sudden wind gusts around urban structures and their potential to destabilize aircraft. Notably, RMIT University’s Uncrewed Aircraft Systems (UAS) Research Team recently published a paper highlighting their findings in this area.

Dr. Abdulghani Mohamed, a renowned aerospace engineer and the lead researcher in this field, has dedicated over a decade to studying the dynamics of wind gusts. He emphasizes the crucial importance of effectively addressing this aspect through appropriate regulations, both in Australia and internationally, prior to introducing air taxis and other drones into our urban airspace.

Strong wind gusts form around city buildings

According to Dr. Abdulghani Mohamed, who conducted the research at RMIT, low-flying aircraft are particularly vulnerable to wind gusts due to their slower landing and takeoff speeds. The study conducted by the RMIT team has uncovered that sudden wind gusts can present significant safety obstacles for air taxis and drones in less than a second.

Consequently, Dr. Abdulghani Mohamed explains that air taxis and drones will require additional power during their landing or takeoff maneuvers in urban environments, in contrast to airports or open spaces.

Dr. Abdulghani Mohamed, from the School of Engineering, clarifies that air taxis and drones necessitate robust motors capable of swiftly adjusting the propeller thrust to promptly correct the vehicle’s course. This process demands a higher energy consumption compared to other scenarios.

Making our city skies safe

Across the globe, regulations pertaining to Advanced Air Mobility (AAM) aircraft, including upcoming air taxis, are being developed. Both the US and Europe are actively involved in compiling these regulations. The RMIT team strongly emphasizes the necessity of establishing weather frameworks to ensure the safety and reliability of this emerging technology.

Mohamed emphasized that regulations and certification processes should specifically focus on ensuring the safe operation of air taxis and drones when navigating through the flow fields created by buildings.

He asserts that it is crucial to conduct site-specific wind simulations and measurements in order to identify potentially hazardous areas.

“In determining the placement of vertiports, which serve as the takeoff and landing locations for these vehicles, it is imperative that we also identify and avoid hazardous regions,” explained Mohamed. He further emphasized that this approach would enhance safety, mitigate potential disruptions caused by adverse wind conditions, and contribute to the smooth operation of the air taxi fleet.

“The responsibility for addressing this matter in Australia is yet to be clearly defined, whether it falls under CASA’s jurisdiction or the Bureau of Meteorology,” stated Mohamed. However, he highlights that air taxis will require weather information at significantly higher resolution and faster rates than what is presently achievable. This is crucial for effective flight planning and operational decision-making.

“The margin of error for air taxis in cities will be significantly lower compared to airports, as larger aircraft can tolerate stronger gusts. Unfortunately, we won’t have the same level of flexibility with air taxis operating in urban environments,” explained Mohamed.

Next steps 

Dr. Abdulghani Mohamed stated, “By designing purpose-built vertiports, we have the opportunity to incorporate geometric features that can minimize the occurrence of hazardous flow conditions. We are currently exploring this aspect in our ongoing research.”

Dr. Abdulghani Mohamed suggests that existing buildings can be repurposed as vertiports, but certain modifications might be necessary to enhance aerodynamics near the landing pads. The effectiveness of these design features can be evaluated through scaled experiments conducted in wind tunnels or through full-scale measurements.

Dr. Abdulghani Mohamed expresses optimism about the future, stating that conducting extensive full-scale wind flow mapping will no longer be a daunting task. He explains that their team is actively working on the development of wind sensing drones, which comprise a swarm of drones equipped with wind anemometers. This innovative approach enables highly accurate mapping of wind patterns around large infrastructures.

The research paper titled “Gusts Encountered by Flying Vehicles in Proximity to Buildings” has been published in MDPI’s Drones journal, with the DOI: 10.3390/drones7010022. The recommendations presented in this paper hold significant potential in influencing the regulation of vertiports, flight paths, and the requirements for air taxis in Australia, as well as on a global scale.

The researchers are actively pursuing further investigations into wind gusts around buildings, with a particular focus on exploring different building shapes that could potentially minimize adverse effects. Additionally, their research efforts extend to studying the sensitivity of vehicles to gusts and turbulence, along with examining flight-stability technologies. This ongoing research aims to advance our understanding of these crucial aspects and contribute to the development of safer and more efficient air taxi operations.

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.