Simon Watkins

RMIT University | RMIT · Sir Lawrence Wackett Aerospace Centre

Insects excel in trajectory and attitude handling during flight, yet the specific kinematic behaviours they use for maintaining stability in air disturbances are not fully understood. This study investigates the adaptive strategies of bumblebees when exposed to gust disturbances directed from three different angles within a plane cross-sectional to...

Wind-hovering birds exhibit remarkable steadiness in flight, achieved through the morphing of their wings and tail. We analysed the kinematics of two nankeen kestrels (Falco cenchroides) engaged in steady wind-hovering flights in a smooth flow wind tunnel. Motion-tracking cameras were used to capture the movements of the birds as they maintained th...

This study investigates the use of rapidly actuated leading-edge and trailing-edge control surfaces to improve the control authority of small fixed-wing drones. Static and dynamic characteristics were investigated and presented in two separate papers. In this paper, the focus is on the dynamic effects observed from rapidly actuated 30% chord leadin...

The eVTOL industry is a rapidly growing mass market expected to start in 2024. eVTOL compete, caused by their predicted missions, with ground-based transportation modes, including mainly passenger cars. Therefore, the automotive and classical aircraft design process is reviewed and compared to highlight advantages for eVTOL development. A special f...

There is a growing desire to operate Uncrewed Air Vehicles (UAVs) in urban environments for parcel delivery, and passenger-carrying air taxis for Advanced Air Mobility (AAM). The turbulent flows and gusts around buildings and other urban infrastructure can affect the steadiness and stability of such air vehicles by generating a highly transient rel...

The use of flying robots (drones) is increasing rapidly, but their utility is limited by high power demand, low specific energy storage and poor gust tolerance. By contrast, birds demonstrate long endurance, harvesting atmospheric energy in environments ranging from cluttered cityscapes to open landscapes, coasts and oceans. Here, we identify new o...

We conducted a field study at a K-12 private school in the suburbs of Melbourne, Australia. The data capture contained two elements: First, a 5-month longitudinal field study In-Gauge using two outdoor weather stations, as well as indoor weather stations in 17 classrooms and temperature sensors on the vents of occupant-controlled room air-condition...

This paper presents a summary of experimental results regarding the propulsive efficiencies of small multirotor propellers, in simulated forward flight conditions. An automated test rig was used in a wind tunnel to measure propeller performance data across a range of flight speeds and angles. Propellers of various pitch were also tested and compare...

Avian flight continues to inspire aircraft designers. Reducing the scale of autonomous aircraft to that of birds and large insects has resulted in new control challenges when attempting to hold steady flight in turbulent atmospheric wind. Some birds, however, are capable of remarkably stable hovering flight in the same conditions. This work describ...

We conducted a field study at a K-12 private school in the suburbs of Melbourne, Australia. The data capture contained two elements: First, a 5-month longitudinal field study In-Gauge using two outdoor weather stations, as well as indoor weather stations in 17 classrooms and temperature sensors on the vents of occupant-controlled room air-condition...

Avian flight continues to inspire aircraft designers. As the scales of autonomous aircraft reduce to those of birds and large insects, new control challenges are apparent when attempting to hold steady flight in turbulent atmospheric wind. Some birds, however, are capable of remarkably stable hovering flight in the same conditions. This work descri...

The use of a leading-edge hinged control surface, as opposed to a traditional trailing-edge hinged control surface, is investigated in the context of improving control authority of fixed-wing Micro Air Vehicles when subject to gusts. Static and dynamics forces are considered in two separate papers (Part I and II). In Part I we document the static l...

The backdrop to the rapidly expanding use of drones is described, including development of drone technology, followed by an overview of current civilian use, focusing on use in and around the urban environment. The inhibitors to further use are considered including technological and societal aspects. The operation and control issues are reviewed in...

The use of unmanned aircraft systems (UAS) or drones is growing, particularly for applications which must be performed near people, such as real-estate aerial photography. Urban UAS operations have led to noise is becoming an increasing concern for the community. The noise generated by a single typical multirotor UAS arm; including propeller and su...

Unmanned Aircraft Systems (UAS) noise is increasingly becoming a concern as drone use becomes commonplace. Propeller noise from manned aircraft has long been a topic of considerable investigation [1], but at the low-Reynolds number of most UAS operations there are few studies [2]. Referencing a popular consumer drone (DJI Phantom 3), several common...

Fixed-wing small, unmanned aerial vehicles (SUAVs) usually fly in atmospheric boundary layers that are often under the influence of turbulent environments. Inspired by nature's flyers, an application of an energy-harvesting flight strategy for increasing the energy state of the aircraft is presented. This paper provides basic longitudinal flight dy...

The stability of small unmanned air systems can be challenged by turbulence during low-altitude flight in cluttered urban environments. This paper explores the benefits of a tandem wing aircraft configuration with the implementation of a pressure-based phase-advanced turbulence sensory system on a small unmanned air system for gust mitigation. The...

Flight is a complicated task at the centimetre scale particularly due to unsteady air fluctuations which are ubiquitous in outdoor flight environments. Flying organisms deal with these difficulties using active and passive control mechanisms to steer their body motion. Body attitudes of flapping organisms are linked with their resultant flight traj...

Micro Air Vehicles (MAVs) have the potential to revolutionize our capabilities in gathering information, monitoring situations, and surveillance. They are required to maneuver in and around obstacles as well as negotiate atmospheric disturbances whilst holding accurate trajectories and minimizing rotation which can blur imagery. A study of existing...

Parachute Systems (PS) can be readily used by small Unmanned Aircraft Systems (UAS) for risk mitigation and aircraft recovery. To date there has been limited research into the fundamental dynamics of parachutes at low Reynolds numbers, with existing studies focusing on larger parachutes. An understanding of the dynamics is needed to establish sound...

Flight is a complicated task at small scales in part due to the ubiquitous unsteady air which contains it. Flying organisms deal with these difficulties using active and passive control mechanisms to steer their body motion. Body attitudes of flapping organisms are linked with their resultant flight trajectories and performance, yet little is under...

Increasingly, operations with unmanned aircraft systems (UAS) are occurring in populous regions. Commercial entities propose increasingly frequent, very low-level flights of a diverse range of small craft (particularly quadrotors) in urban environments. There is a significant body of research addressing safety, security, and privacy issues for UAS...

The utility of micro air vehicles (MAVs) has expanded significantly in the last decade, and there are now numerous commercial systems available at relatively low cost. This expansion has arisen mainly due to the miniaturisation of flight control systems and advances in energy storage and propulsion technologies. Several emerging applications involv...

A low-cost, multi-hole pressure probe for Unmanned Aircraft System airborne flow measurements was developed and tested. The ability of the probe to accurately measure wind direction, velocity magnitude and turbulence intensity in a range of flow conditions was verified against commercially available sensors. The feasibility of applying a general ca...

This work describes the testing involved in generating an acoustic signature profile of a small multi-rotor unmanned aircraft system. A typical multi-rotor unmanned aircraft system, with a weight of approximately 2.1 kg, was used for sound pressure level measurements. This study established a relationship between distance, altitude and sound pressu...

Micro-air vehicles (MAVs) are envisaged to spend a large portion of their mission within urban environments, which in general are rich in large obstacles (both natural and man-made). These obstacles can be a hindrance to MAV flight, but also have the potential to generate orographic updrafts when wind impinges on them. In theory, MAVs can exploit t...

The feasibility of using a Multi-rotor Unmanned Aerial System (MUAS) as flying anemometers for measurement of wind in urban environments was investigated. Flow mapping was conducted around the MUAS using smoke flow visualisa-tion and multi-hole pressure probes to analyse the effects of the propellers on the measured flow speed and direction and det...

Nature's flapping-wing flyers are adept at negotiating highly turbulent flows across a wide range of scales. This is in part due to their ability to quickly detect and counterract disturbances to their flight path, but may also be assisted by an inherent aerodynamic property of flapping wings. In this study, we subject a mechanical flapping wing to...

Strategies for forward-sensing turbulence ahead of an aircraft are introduced, which enable more timely opposing control inputs than for traditional inertial sensing. Typically traditional systems measure the effect of a velocity perturbation on an aircraft and thus can only provide a delayed response when countering the effect. The early acquisiti...

In this paper the feasibility of incorporating a carbon fibre composite half-shaft into the final drive of an electric racing vehicle is studied. Carbon fibre composite tubing is bonded with aluminium inserts to achieve a low mass and high stiffness alternative to conventional half-shaft design. The drive line system was validated using a number of...

This paper explores a method by which an unpowered, fixed-wing micro air vehicle (MAV) may autonomously gain height by utilising orographic updrafts in urban environments. These updrafts are created when wind impinges on both man-made and natural obstacles, and are often highly turbulent and very localised. Thus in contrast to most previous autonom...

MAVs are increasingly being used in complex terrains, such as cities, despite challenges from the highly turbulent flow fields. We investigate the flow around a nominally cuboid building of height 40m both computationally and experimentally in a 1/100th scale wind-tunnel test. A relatively new computational technique, Improved Delayed Detached Eddy...

MAVs are increasingly being used in complex terrains, such as cities, despite challenges from the highly turbulent flow fields. We investigate the flow around a nominally cuboid building of height 40m both computationally and experimentally in a 1/100th scale wind-tunnel test. A relatively new computational technique, Improved Delayed Detached Eddy...

This paper examines the possibility of using a Multi-Rotor Unmanned Aircraft System (MUAS) for atmospheric flow measurements around a tall building. This novel sensing approach is proposed, whereby we attempt to determine the oncoming flow velocity magnitude and direction from measurements of the power required by each of the MUAS rotors. Extensive...

There are significant challenges associated with the flight control of fixed-wing micro air vehicles (MAVs) operating in complex environments. The scale of MAVs makes them particularly sensitive to atmospheric disturbances thus limiting their ability to sustain controlled flight. Bio-inspired, phase-advanced sensors have been identified as promisin...

Fixed-wing Micro Aerial Vehicles (MAVs) experience attitude control difficulties as they operate in highly turbulent environments. Previous research has identified pressure-based control as a potential approach for augmenting the performance of, or replacing, autopilots reliant on inertial sensors. However, implementation requires an in-depth under...

Birds have been observed to soar over ridges, mountains and cliffs to extend their flight duration with minimal energy expenditure. There is an opportunity to replicate this behavior to enhance the flight duration of Micro Aerial Vehicles (MAVs) which operate in urban environments by exploiting the vertical flow component (orographic lift) of flow...

This paper describes a virtual and physical design and prototyping strategy intended to aid designers to understand the relational dynamic between airflow and porous screens for building facades at the conceptual design stage. The strategy consists of three main components: 1) A prototyping phase involving a combination of computer aided modeling (...

Wild bird management at airports and sporting venues is a significant issue. Numerous methods for managing birds are used. Falconry has proven the most effective solution but it is not without its limitations; predatory birds are temperamental, can be difficult to manage, and are unable to be flown at night. The aim of this research is to develop a...

The outdoor turbulent wind environment close to the ground is reviewed and then movement through this environment is considered. Even under average winds it is shown that the turbulence levels in the relative flow field can be significant. Flows, and thus forces and moments, around many shapes associated with sport (e.g. sporting balls and semi-blu...

The Melbourne Metropolitan Fire Brigade are exploring the fitment of Hazardous Materials sensors to a quadrotor Unmanned Aircraft System (UAS). The aim of this paper is determine whether the flow structures surrounding the quadrotor would be sufficient to support measurements made by the sensor. Flow visualisation techniques (Schilieren) and point...

It has been some time since a concept involving flutter of piezoelectric harvesters was introduced. A basic underpinning of how these harvester types operate in smooth, parallel-flow conditions has been realised in analytical, computational and experimental investigations. Preliminary findings show that these harvesters could potentially suppl...

This paper will focus on determining characteristics of tyre cavity resonance noise and its mitigation method. There are many factors that affect the noise transmitted to vehicle cabin, this includes coupling mode of structure and tyre air cavity which will be investigated in this paper. The results from experimental modal analysis will be compa...

This paper presents a novel electronic differential design for highperformance electric vehicles (EVs) with independent driving motors. The aim of this design is to achieve neutral-steer in intense driving scenarios. The proposed method employs a closed-loop control system that constantly regulates the torque commands sent to the independent drivin...

Fixed-wing Micro-Aerial Vehicles (MAVs) need effective sensors that can rapidly detect turbulence induced motion perturbations. Current MAV attitude control systems rely on inertial sensors. These systems can be described as reactive; detecting the disturbance only after the aircraft has responded to the disturbing phenomena. In this part of the pa...

Experiments at low Reynolds numbers were performed on a pressure tapped NACA2313 wing in a 3 x 2 x 9 meter wind tunnel under nominally smooth (Ti = 1.2%) and turbulent (Ti = 7.2%) flows at a mean flow velocity of 8ms-1 (Re ≈ 120,000). The NACA2313 wing is a replica of a Micro Air Vehicle (MAV) wing of the Flash 3D aircraft used at RMIT University f...

The evaluation of a low-tech wind sensing platform for urban aerodynamic simulations relevant to pedestrian comfort. In this paper, the wind canyon effect is simulated with two different building morphologies. The platform provides conceptual knowledge of the dynamics in wind relevant for designers, architectural practitioners and students of desig...

This paper presents an experimental study on strategies of utilizing wind as an architectural element, proposing the reconfiguration and projection of wind patterns to produce vaults of wind as regions of shelter in the outdoor environment. It shows an aerodynamic analysis and exploration of barriers, deflectors and porous screens in an existing ur...