An Investigation of Fixed and Rotary Wing MAV Flight in Replicated Atmospheric Turbulence

Loxton, B.; Abdulrahim, Mujahid; Watkins, Simon

doi:10.2514/6.2008-227

Cited by 12 publications

(7 citation statements)

References 7 publications

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“…The airframe is suitably rigid to withstand normal aerodynamic loads, yet it is sufficiently flexible to absorb impact energy and prevent or reduce airframe damage. In previous flight trials [5] in the turbulent wind tunnel, a large portion of the testing time was occupied by airframe and system repairs following crashes.…”

Section: B Aircraftmentioning

confidence: 99%

“…The achievable wind speeds in this section range from 0 to nearly 15 m=s, which is sufficient for most small aircraft. Detailed descriptions of the wind-tunnel facility are provided in a 2008 paper by Loxton et al [5].…”

Section: A Wind Tunnelmentioning

confidence: 99%

“…All flight tests are performed with a fixed wind-tunnel speed of 8 m=s and a fixed wind-tunnel configuration, which results in an average turbulence intensity of 6.6%, with a length scale of 1.2 m. The wind tunnel is configured with the jet down, the collector in the forward position, no grids in the upper section, and two screens in the lower section [5]. The constant speed for the tests necessitates flight at varying trim angles of attack due to the change in mass for some configurations.…”

Section: B Turbulent Wind-tunnel Flight Testingmentioning

confidence: 99%

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Dynamic Sensitivity to Atmospheric Turbulence of Unmanned Air Vehicles with Varying Configuration

Abdulrahim

Watkins

Segal

et al. 2010

Journal of Aircraft

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Air vehicle flight in turbulence is generally treated as an anomalous part of the flying environment. Aircraft geometries and flight-control systems are often designed and tested for calm atmospheric conditions, where both steady winds and gusts are minor. As a result, the flight performance of small aircraft deteriorates in the presence of atmospheric turbulence, where gust disturbances can be large relative to the flying speeds. A better approach is needed in the aircraft and control system design process that specifically accounts for the effects of turbulence and provides a means of mitigating disturbances to improve the mission effectiveness of micro unmanned air vehicles and small unmanned air vehicles. The current research considers untethered flight tests of a small unmanned air vehicle in a large wind engineering tunnel that can be configured to replicate turbulence levels expected from urban and suburban environments. Systematic changes to the configuration of the fixed-wing aircraft are made to evaluate the role of metrics, such as c.g., mass, moment of inertia, wingspan, and wing loading to turbulence sensitivity. Estimates of the force and moment disturbances indicate that some parameters, such as moment of inertia, have simple and expected influences on the response to turbulence. Conversely, wing area and mass have conflicting effects due to the compounded influences on the aircraft response. The sensitivity of the various aircraft configurations to turbulence are presented as control equivalent turbulence disturbances, which equate forces and moments acting on the airframe to control deflections. This method normalizes the aircraft responses with respect to the ability to suppress disturbances with actuated controls. Nomenclature A = system dynamics a y = lateral acceleration a z = vertical acceleration B = control effectiveness b = wingspan C = state observation c = wing chord E = disturbance dynamics F = fit quality I x;y;z = moments of inertia I xz = product of inertia l = rolling moment m = pitching moment n = yawing moment p = roll rate q = pitch rate q = dynamic pressure r = yaw rate S = wing area u, = control input V 0 = velocity x = state vector Y = side force y = measurements Z = vertical force = angle of attack = angle of sideslip Subscripts d = disturbance force/moment lat = lateral lon = longitudinal T = total force/moment contributions a = aircraft-only force/moment contributions a = aileron e = elevator r = rudder

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Section: B Aircraftmentioning

confidence: 99%

Section: A Wind Tunnelmentioning

confidence: 99%

Section: B Turbulent Wind-tunnel Flight Testingmentioning

confidence: 99%

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Dynamic Sensitivity to Atmospheric Turbulence of Unmanned Air Vehicles with Varying Configuration

Abdulrahim

Watkins

Segal

et al. 2010

Journal of Aircraft

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“…Consequently, it is anticipated that multirotor UAS will dominate urban operations. Fortunately, flight testing has demonstrated that multirotor aircraft are less susceptible to the effects of turbulence than their fixed-wing counterpart and that piloting difficulty scales less with multirotors, compared to fixed-wing air vehicles, when turbulence levels increase (Loxton, Abdulrahim, & Watkins, 2008;. While comparisons such as these must obviously take place between UA with comparable mass and moment of inertia, it should be kept in mind that effective turbulence intensity will decrease, as described above, for a fast rotating rotor blade compared to a slower moving fixed-wing .…”

Section: Affect Of the Environment On Suasmentioning

confidence: 99%

“…While comparisons such as these must obviously take place between UA with comparable mass and moment of inertia, it should be kept in mind that effective turbulence intensity will decrease, as described above, for a fast rotating rotor blade compared to a slower moving fixed-wing . Regardless, flight testing has also demonstrated that the high frequency of control inputs required in highly turbulent conditions can exceed even the capability of experienced pilots for both multirotor and fixed-wing UA (Loxton et al, 2008;. As a result, improvements in disturbance rejection strategies continue to be investigated (Sydney, Smyth, & Paley, 2013b;Szczublewski, 2012;Tran, Bulka, & Nahon, 2015;Yeo, Sydney, & Paley, 2016).…”

Section: Affect Of the Environment On Suasmentioning

confidence: 99%

Urban flow and small unmanned aerial system operations in the built environment

Adkins¹

2019

IJAAA

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On Low Altitude Flight through the Atmospheric Boundary Layer

Watkins

Thompson

Loxton

et al. 2010

International Journal of Micro Air Vehicles

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Major challenges to low speed micro flight are the transient and time-averaged velocities arising from the Atmospheric Boundary Layer (ABL), particularly turbulence a few metres above the ground. In this paper, existing data from meteorologists and wind engineers are reviewed and measurements dedicated to understanding the spatial and temporal velocity fields that MAVs experience are briefly described. Data from a wide variety of terrains are analysed, with the majority of data obtained in relatively well mixed turbulent flow (i.e. away from local effects such as buildings) and for conditions of nominally neutral stability. Spectra for data well removed from local effects exhibited the expected 5/3rds Kolmogorov law. Transient flow pitch angles were investigated (obtained from four small laterally displaced probes), in order to understand the possible roll and pitch inputs to MAVs. It was noted that for all data obtained the variation with lateral separation decreased relatively slowly with reducing separation down to the closest inter-probe spacing of 14mm. This effect is thought to explain the increasing piloting difficulties experienced in maintaining good roll control for decreasing scales of craft when any appreciable atmospheric winds are present.

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An Investigation of Fixed and Rotary Wing MAV Flight in Replicated Atmospheric Turbulence

Cited by 12 publications

References 7 publications

Dynamic Sensitivity to Atmospheric Turbulence of Unmanned Air Vehicles with Varying Configuration

Dynamic Sensitivity to Atmospheric Turbulence of Unmanned Air Vehicles with Varying Configuration

Urban flow and small unmanned aerial system operations in the built environment

On Low Altitude Flight through the Atmospheric Boundary Layer

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