Hares in the long grass: increased aircraft related mortality of the Irish hare (Lepus timidus hibernicus) over a 30-year period at Ireland’s largest civil airport

Collisions between wildlife and aircraft are a serious and growing threat to aviation safety. Understanding the frequency of these collisions, the identity of species involved, and the potential damage that can be inflicted on to aircraft aid mitigation efforts by airfield managers. A record of all animal carcasses recovered from Dublin International Airport, Ireland’s largest civil aviation airport, has been maintained since 1990 where strikes with the endemic Irish hare (Lepus timidus hibernicus), a protected subspecies of mountain hare, are of particular concern despite substantial management efforts from the airfield authority. The first strike event with a hare was recorded in 1997, and strike events have substantially increased since then, with a sharp increase recorded in 2011. Over a 30-year period, a total of 320 strike events with the Irish hare have been recorded at the airfield. To date, no strike event with a hare has resulted in damage to an aircraft. However, carcasses can present as a major attraction to avian scavenger species in addition to posing as a risk of causing foreign object damage in the event of an undetected carcass. Hare strikes are discussed in the context of the rate of civil aircraft movements, possible direct and indirect damage to aircraft, and airfield wildlife hazard management. Here, we demonstrate that not only are strike events increasing by 14% on an annual basis, but that the kinetic energy of such an event has the potential to cause significant damage to an aircraft.

Computational Study of the Propeller Position Effects in Wing-Mounted, Distributed Electric Propulsion with Boundary Layer Ingestion in a 25 kg Remotely Piloted Aircraft

Distributed electric propulsion and boundary layer ingestion are two attractive technologies to reduce the power consumption of fixed wing aircraft. Through careful distribution of the propulsive system elements, higher aerodynamic and propulsive efficiency can be achieved, as well as a lower risk of total loss of aircraft due to foreign object damage. When used on the wing, further reductions of the bending moment on the wing root can even lead to reductions of its structural weight, thus mitigating the expected increase of operating empty weight due to the extra components needed. While coupling these technologies in fixed-wing aircraft is being actively studied in the big aircraft segment, it is also an interesting approach for increasing the efficiency even for aircraft with maximum take-off masses as low as 25 kg, such as the A3 open subcategory for civil drones from EASA. This paper studies the effect of changing the propellers’ position in the aerodynamic performance parameters of a distributed electric propulsion with boundary layer ingestion system in a 25 kg fixed-wing aircraft, as well as in the performance of the propellers. The computational results show the trade-offs between the aerodynamic efficiency and the propeller efficiency when the vertical position is varied.

Precast Concrete Paving Repairs at Vancouver International Airport

In 2019, Vancouver International Airport conducted a precast concrete panel replacement pilot project on Taxiway Victor to establish whether precast concrete was a viable option for a planned runway repair project. This was the first major use of precast airfield pavement in North America in nearly 20 years. Twelve panels measuring 6 m × 7.5 m with a thickness of 360 mm and weighing up to 43 metric tons each were installed to demonstrate the viability of in-situ concrete panel replacement in 8-h night work windows. The panels were designed as heavily reinforced “ductile slabs”; conventional pavement design procedures would have required much greater slab thickness and removal/replacement of base material, which would have greatly slowed panel replacements. Load transfer was provided by 38-mm diameter galvanized steel dowels, which were spaced nonuniformly along each panel edge. The use of bottom slots presented a clean surface with minimal potential for foreign object damage. Five of the panels included embedded airfield light cans, which required great placement precision to ensure their proper alignment and function. Seven of the panels were nonplanar, requiring a special first-of-its-kind warped casting bed that was large enough to produce nonplanar airfield-sized panels to the specified fabrication tolerances. Many valuable lessons were learned during this pilot project, which confirmed that long-life jointed precast concrete pavement repairs could be successfully constructed in 8-h overnight work windows on an active airfield using large repair panels and doweled joints, while adhering to strict panel-to-panel elevation tolerances.