Steady flight of kestrels could help aerial safety soar

Steady flight of kestrels could help aerial safety soar

A joint study by RMIT and the University of Bristol has revealed secrets to the remarkably steady flight of kestrels that could inform future drone design and flight control strategies.

Making drones safer and more stable in turbulent conditions, or in cities where wind gusts from tall buildings make flying more difficult, makes applications like parcel delivery, food delivery and environmental monitoring more feasible, more often.  

The study conducted in RMIT’s Industrial Wind Tunnel facility – one of the largest of its kind in Australia – is the first to precisely measure the stability of a Nankeen Kestrel’s head during hovering flight, finding movement of less than 5mm during hunting behaviour.  

“Typically, aircraft use flap movements for stabilisation to achieve stability during flight,” said RMIT lead researcher Dr Abdulghani Mohamed.  

“Our results acquired over several years, show birds of prey rely more on changes in surface area, which is crucial as it may be a more efficient way of achieving stable flight in fixed wing aircraft too.”

Martin Scuffins from the Leigh Valley Hawk and Owl Sanctuary and RMIT's Dr Abdulghani Mohamed fitting sensors to the kestrel in RMIT's wind tunnel facility. Martin Scuffins from the Leigh Valley Hawk and Owl Sanctuary and RMIT's Dr Abdulghani Mohamed fitting sensors to the kestrel in RMIT's wind tunnel facility.

Anatomy of steady flight 

Kestrels and other birds of prey are capable of keeping their heads and bodies extremely still during hunting. This specialised flight behaviour, called wind hovering, allows the birds to ‘hang’ in place under the right wind conditions without flapping. By making small adjustments to the shape of their wings and tail, they can achieve incredible steadiness. 

Thanks to advancements in camera and motion capture technology, the research team was able to observe two Nankeen Kestrels, trained by Leigh Valley Hawk and Owl Sanctuary, at high resolution. 

Fitted with reflective markers, the birds’ precise movements and flight control techniques during non-flapping flight were tracked in detail for the first-time.

“Previous studies involved birds casually flying through turbulence and gusts within wind tunnels; in our study we tracked a unique wind hovering flight behaviour whereby the birds are actively maintaining extreme steadiness, enabling us to study the pure control response without flapping,” said Mohamed. 

By mapping these movements, the researchers gained insights that could be utilised to achieve steadier flight for fixed wing aircrafts. 

“The wind hovering behaviour we observed in kestrels is the closest representation in the avian world to fixed wing aircraft,” said Mohamed.  

“Our findings surrounding the changes in wing surface area could be applied to the design of morphing wings in drones, enhancing their stability and making them safer in adverse weather.” 

 

steady-flight-of-kestrels-could-see-aerial-safety-soar-thumbnail.jpg

Steady flight of kestrels could see aerial safety soar

The issue with current drones 

Associate Professor of Bio-Inspired Aerodynamics at Bristol University and joint last author, Dr Shane Windsor, said the usefulness of current fixed wing unmanned aerial vehicles (UAV’s) was significantly decreased by their inability to operate in gusty wind conditions.  

“UAV’s are being used in the UK to deliver post to remote islands, but their operation time is limited because of regular gusty conditions.  

“Current commercial fixed wing aircraft have to be designed with one fixed geometry and optimised to operate at one flight condition. 

“The advantage of morphing wings is that they could be continually optimised throughout a flight for a variety of conditions, making the aircraft much more manoeuvrable and efficient.” 

Next steps

The team now aims to further their research by examining the birds under gusty and turbulent conditions, which would see further learnings in stable flight with the goal of allowing UAVs to operate more safely and more often.

While initially focused on smaller aerial vehicles, the team hopes to simplify the data collected so that it can be adapted for larger scale aircraft.  

‘Steady as they hover: kinematics of kestrel wing and tail morphing during hovering flights’ published in the Journal of Experimental Biology (https://doi.org/10.1242/jeb.247305) is a collaboration between Mario Martinez Groves-Raines, George Yi, Matthew Penn, Simon Watkins, Shane Windsor and Abdulghani Mohamed. 

The team acknowledges Mr Martin Scuffins from the Leigh Valley Hawk and Owl Sanctuary, for supporting the project and sharing expertise and knowledge critical to the project’s success. 

 

Story: Seamus Daniel

08 August 2024

Share

08 August 2024

Share

  • Research
  • Aerospace & Aviation
  • Engineering
  • Science and technology
Engage

Related News

Photo of Dr Yassie Samie

Study calls for city fashion waste shakeup

With most donated clothes exported or thrown away, experts are calling for a shakeup of how we deal with the growing fashion waste issue.

Tree canopy at a park

Major Australian cities fail international tree canopy goals: study

New research measuring access to nature for eight major global cities, including central Melbourne and Sydney, found most have inadequate canopy cover despite access to an abundance of trees.

news-aroma-intensity-1220px.jpg

Confinement may affect how we smell and feel about food

New research from RMIT University found confined and isolating environments changed the way people smelled and responded emotionally to certain food aromas.

Thumbnail_RA_Awards_2024_MEDIA_WALL.jpg

Aged care digital health tool recognised again on national stage

Australia’s first electronic screening and risk prediction tool for deterioration in aged care residents has won another national prize for its positive impact on health and safety.

Show more
aboriginal flag
torres strait flag

Acknowledgement of Country

RMIT University acknowledges the people of the Woi wurrung and Boon wurrung language groups of the eastern Kulin Nation on whose unceded lands we conduct the business of the University. RMIT University respectfully acknowledges their Ancestors and Elders, past and present. RMIT also acknowledges the Traditional Custodians and their Ancestors of the lands and waters across Australia where we conduct our business - Artwork 'Sentient' by Hollie Johnson, Gunaikurnai and Monero Ngarigo.

More information