Design and Development of a High-Speed UAS for beyond Visual Line-of-Sight Operations

McCrink, Matthew; Gregory, James W.

doi:10.1007/s10846-020-01300-2

Cited by 8 publications

(3 citation statements)

References 27 publications

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“…The helicopter system allowed us to obtain aerial imagery over much larger areas with a spatial resolution equivalent to what we can obtain with sUAS platforms and also allowed us to collect imagery in areas that were chronically cloudy and challenging to image acquisition using satellite platforms. Within the near future, with more capable platforms and changes to the regulatory framework for beyond visual line of sight operations [59,60], we anticipate replacing the manned helicopter imaging system with a UAS platform. Until that time, in Hawai'i and other places with rugged and remote terrain and persistent cloud cover, helicopter-based imaging systems can support a variety of conservation and land management needs over landscape scales [61][62][63].…”

Section: Confidence Ratings and Laboratory Sample Resultsmentioning

confidence: 99%

Spatial Patterns of ‘Ōhi‘a Mortality Associated with Rapid ‘Ōhi‘a Death and Ungulate Presence

Perroy

Sullivan

Benitez

et al. 2021

Forests

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Effective forest management, particularly during forest disturbance events, requires timely and accurate monitoring information at appropriate spatial scales. In Hawai‘i, widespread ‘ōhi‘a (Metrosideros polymorpha Gaud.) mortality associated with introduced fungal pathogens affects forest stands across the archipelago, further impacting native ecosystems already under threat from invasive species. Here, we share results from an integrated monitoring program based on high resolution (<5 cm) aerial imagery, field sampling, and confirmatory laboratory testing to detect and monitor ‘ōhi‘a mortality at the individual tree level across four representative sites on Hawai‘i island. We developed a custom imaging system for helicopter operations to map thousands of hectares (ha) per flight, a more useful scale than the ten to hundreds of ha typically covered using small, unoccupied aerial systems. Based on collected imagery, we developed a rating system of canopy condition to identify ‘ōhi‘a trees suspected of infection by the fungal pathogens responsible for rapid ‘ōhi‘a death (ROD); we used this system to quickly generate and share suspect tree candidate locations with partner agencies to rapidly detect new mortality outbreaks and prioritize field sampling efforts. In three of the four sites, 98% of laboratory samples collected from suspect trees assigned a high confidence rating (n = 50) and 89% of those assigned a medium confidence rating (n = 117) returned positive detections for the fungal pathogens responsible for ROD. The fourth site, which has a history of unexplained ‘ōhi‘a mortality, exhibited much lower positive detection rates: only 6% of sampled trees assigned a high confidence rating (n = 16) and 0% of the sampled suspect trees assigned a medium confidence rating (n = 20) were found to be positive for the pathogen. The disparity in positive detection rates across study sites illustrates challenges to definitively determine the cause of ‘ōhi‘a mortality from aerial imagery alone. Spatial patterns of ROD-associated ‘ōhi‘a mortality were strongly affected by ungulate presence or absence as measured by the density of suspected ROD trees in fenced (i.e., ungulate-free) and unfenced (i.e., ungulate present) areas. Suspected ROD tree densities in neighboring areas containing ungulates were two to 69 times greater than those found in ungulate-free zones. In one study site, a fence line breach occurred during the study period, and feral ungulates entered an area that was previously ungulate-free. Following the breach, suspect ROD tree densities in this area rose from 0.02 to 2.78 suspect trees/ha, highlighting the need for ungulate control to protect ‘ōhi‘a stands from Ceratocystis-induced mortality and repeat monitoring to detect forest changes and resource threats.

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Section: Confidence Ratings and Laboratory Sample Resultsmentioning

confidence: 99%

Spatial Patterns of ‘Ōhi‘a Mortality Associated with Rapid ‘Ōhi‘a Death and Ungulate Presence

Perroy

Sullivan

Benitez

et al. 2021

Forests

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“…In this paper we focus on the lift and drag curves at low mach numbers, as they are the starting point of most performance calculations, operational simulations and contingency analyses. There is a rich literature around the estimation of drag curves on small, uncrewed, fixed wing platforms, ranging from methods based on battery energy depletion [1], to thrust estimation [2][3][4][5][6] and to methods involving unpowered manoeuvres [7][8][9][10][11]. We are, however, not aware of any systematic comparisons of these methods, in terms of their accuracy and ease of implementation, and filling this gap is the goal of this paper.…”

Section: Introductionmentioning

confidence: 99%

“…), the on-board intelligence of the autopilot must be able to re-plan its tasking accordingly (ideally with error margins attached, obtained, for example, through an ensemble of Monte Carlo runs of the performance model). Once again, attempting to do this with with rudimentary baseline performance guesses carries vast penalties in terms of unnecessarily conservative fuel reserves (such as McCrink and Gregory [7] who took off with ∼ 190% more fuel than the mass calculated to complete the mission), unnecessarily aborted missions, or, worse, accidents caused by fuel starvation.…”

Section: Introductionmentioning

confidence: 99%

Experimental evaluation of the drag curves of small fixed wing UAVs

Weishäupl¹,

McLay²,

Sóbester³

2023

Aeronaut. j.

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Tight budgets often limit the scope of test campaigns within the development programmes of small uncrewed air vehicles (UAVs). This paper explores a range of combinations of instrumentation suites and protocols for both wind tunnel and flight evaluation, focusing on the key aspect of drawing up the drag curve of the airframe. Through extensive testing of a 5kg maximum take-off mass, fixed wing, twin motor, richly instrumented test platform, we show that automated glides over a range of airspeeds and the slow down manoeuvre are effective ways of determining power-off drag, while estimating thrust from propeller speed, and voltage and current sensing based methods work well for the power-on case. We also seek the most time-efficient and robust mix of the above manoeuvres to yield a given drag curve accuracy level and we find wind condition impacts the manoeuvre makeup of the optimal strategy.

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Introduction

2021

Introduction to Flight Testing

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Design and Development of a High-Speed UAS for beyond Visual Line-of-Sight Operations

Cited by 8 publications

References 27 publications

Spatial Patterns of ‘Ōhi‘a Mortality Associated with Rapid ‘Ōhi‘a Death and Ungulate Presence

Spatial Patterns of ‘Ōhi‘a Mortality Associated with Rapid ‘Ōhi‘a Death and Ungulate Presence

Experimental evaluation of the drag curves of small fixed wing UAVs

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