Drag reduction through higher wing loading

A reduction in wing area, thickness, and span increases wing loading and lowers parasitic drag for a typical light airplane by 10.5%

Flight Speeds among Bird Species: Allometric and Phylogenetic Effects

Flight speed is expected to increase with mass and wing loading among flying animals and aircraft for fundamental aerodynamic reasons. Assuming geometrical and dynamical similarity, cruising flight speed is predicted to vary as (body mass)1/6 and (wing loading)1/2 among bird species. To test these scaling rules and the general importance of mass and wing loading for bird flight speeds, we used tracking radar to measure flapping flight speeds of individuals or flocks of migrating birds visually identified to species as well as their altitude and winds at the altitudes where the birds were flying. Equivalent airspeeds (airspeeds corrected to sea level air density, Ue) of 138 species, ranging 0.01–10 kg in mass, were analysed in relation to biometry and phylogeny. Scaling exponents in relation to mass and wing loading were significantly smaller than predicted (about 0.12 and 0.32, respectively, with similar results for analyses based on species and independent phylogenetic contrasts). These low scaling exponents may be the result of evolutionary restrictions on bird flight-speed range, counteracting too slow flight speeds among species with low wing loading and too fast speeds among species with high wing loading. This compression of speed range is partly attained through geometric differences, with aspect ratio showing a positive relationship with body mass and wing loading, but additional factors are required to fully explain the small scaling exponent of Ue in relation to wing loading. Furthermore, mass and wing loading accounted for only a limited proportion of the variation in Ue. Phylogeny was a powerful factor, in combination with wing loading, to account for the variation in Ue. These results demonstrate that functional flight adaptations and constraints associated with different evolutionary lineages have an important influence on cruising flapping flight speed that goes beyond the general aerodynamic scaling effects of mass and wing loading

Species With Greater Aerial Maneuverability Have Higher Frequency of Collisions With Aircraft: A Comparative Study

Antipredator responses may appear unsuccessful when animals are exposed to approaching vehicles, often resulting inmortality. Recent studies have addressed whether certain biological traits are associated with variation in collision risk with cars, but not with higher speed-vehicles like aircraft. Our goal was to establish the association between different species traits (i.e., body mass, eye size, brain size, wing loading, wing aspect ratio) and the frequency of bird collisions with aircraft (hereafter, bird strikes) using a comparative approach controlling for the effects of shared ancestry. We proposed directional predictions as to how each of the species traits would affect the frequency of bird strikes. Considering 39 bird species with all traits represented, the model containing wing loading had the best fit to account for the variance in bird strikes across species. In another model with 54 species exploring the fit to different polynomial models but considering only wing loading, we found that wing loading was negatively and linearly associated with the frequency of bird strikes. Counterintuitively, species with lower wing loading (hence, greater maneuverability) had a higher frequency of bird strikes. We discuss potential non-mutually exclusive explanations (e.g., high wing loading species fly faster, thus gaining some extra time to avoid the aircraft flight path; high wing loading species are hazed more intensively at airports, which could lower collisions, etc.). Ultimately, our findings uncovered that species with low wing loading get struck at a higher rate at airports, which reduces the safety risk for humans because these species tend not to cause damaging strikes, but the ecological consequences of their potentially higher local mortality are unknown

Thrust and wing loading requirements for short haul aircraft constrained by engine noise and field length

Propulsion system and wing loading requirements are determined for a mechanical flap and an externally blown flap aircraft for various engine noise levels and two engine cycles. Both aircraft are sized to operate from a 914m (3000 ft) runway and perform the same mission. For each aircraft concept, propulsion system sizing is demonstrated for two different engine cycles - one having a fan pressure ratio of 1.5 and a bypass ratio of 9, and the other having a fan pressure ratio of 1.25 and a bypass ratio of 17.8. The results presented include the required thrust-to-weight ratio, wing loading, resulting gross weight, and direct operating costs, as functions of the engine noise level, for each combination of engine cycle and aircraft concept

WING LOADING IN PLECOTUS RAFINESQUII

Considerable interest has developed in recent years with regard to studies of wing areas and wing loadings of North American bats (Davis and Cockrum, 19645; Jones, 1967; Davis, 1969; Farney and Fleharty, 1969). To our knowledge, such data have not been presented for Plecotus rafinesquii, one of the least known of North American species (Barbour and Davis, 1969). The purpose of this report is to provide information on flight of P. rafinesquii species, as well as adults of two other species of Plecotus. Seventy-one P. rafinesquii were studied: five were banded and released and 66 were preserved either as skins and skulls or in fluid and deposited in the United States National Museum (USNM) or in the Vertebrate Collections of Tulane University (TU). The animals were observed and collected 12 mi. W Woodville, Wilkson Co., Mississippi, on 11 June 1970 (29 USNM, 29 TU) and on the Riverside Campus of Tulane University, Plaquemines Parish, Louisiana, on 30 June and 31 July 1970 (8 TU). At the former locality bats were found in an abandoned house; at the latter site animals were located beneath old ammunition-storage bunkers

Variation in mass and wing loading of nestling American Kestrels: possible effects of nestling behavior and adult provisioning behavior

Among birds, the rapid growth rates of altricial young help reduce mortality by reducing the amount of time spent in the nest. However, in species where a high degree of maneuverability and speed is required (i.e. aerial insectivores), it is important that nestlings not gain excess weight. Nestlings in some species must attain an efficient wing loading just prior to fledging to facilitate mobility for hunting and evading predators. My objective was to examine the mass of nestling American Kestrels (Falco sparverius) during the mid- to late nestling period and specifically to determine the possible effects of attaching small lead weights (3gm and 6gm) to some nestlings. If wing loading at fledging is important for nestling kestrels, then the mass of nestlings with and without weights attached might differ at fledging whereas wing-loading values should be similar. My study was conducted during the 2016 breeding season at the Blue Grass Army Depot in Madison County, Kentucky. Nestling kestrels (n = 40) in 12 broods were divided into three treatment groups: control (n = 12), half-weighted (n = 14), and full-weighted (n = 14). At day 15 post-hatching, half-weighted nestlings received 3-g lead weights and weighted nestlings received 6-g weights, representing 2.5% and 5% of mean adult body mass. I used video recordings to monitor parental provisioning behavior and nestling begging behavior. After subtracting the mass of the lead weights, there were no differences among the treatment groups in mass or wing loading prior to fledging. Over the course of the nestling period, there was no change in the amount of prey biomass delivered per nestling per hour. However, there was a difference in the begging intensity, percent time begging, and activity levels by the nestlings in the days prior to fledging. These results suggest that the asymptotic mass of nestling kestrels is not due to parental behavior. Instead, a combination of physiological processes and nestling behavior may be influencing the asymptotic mass. The lack of difference in mass and wing loading among treatment groups may be due to the greater flexibility in wing loading required by predatory birds. These results also suggest that achieving optimum wing loading prior to fledging is less critical for American Kestrels than for smaller insectivorous birds

Performance of high-altitude, long-endurance, turboprop airplanes using conventional or cryogenic fuels

An analytical study has been conducted to evaluate the potential endurance of remotely piloted, low speed, high altitude, long endurance airplanes designed with 1990 technology. The baseline configuration was a propeller driven, sailplane like airplane powered by turbine engines that used JP-7, liquid methane, or liquid hydrogen as fuel. Endurance was measured as the time spent between 60,000 feet and an engine limited maximum altitude of 70,000 feet. Performance was calculated for a baseline vehicle and for configurations derived by varying aerodynamic, structural or propulsion parameters. Endurance is maximized by reducing wing loading and engine size. The level of maximum endurance for a given wing loading is virtually the same for all three fuels. Constraints due to winds aloft and propulsion system scaling produce maximum endurance values of 71 hours for JP-7 fuel, 70 hours for liquid methane, and 65 hours for liquid hydrogen. Endurance is shown to be strongly effected by structural weight fraction, specific fuel consumption, and fuel load. Listings of the computer program used in this study and sample cases are included in the report

Evaluation of low wing-loading fuel conservative, short-haul transports

Fuel conservation that could be attained with two technology advancements, Q fan propulsion system and active control technology (ACT) was studied. Aircraft incorporating each technology were sized for a Federal Aviation Regulation (FAR) field length of 914 meters (3,000 feet), 148 passengers, and a 926 kilometer (500 nautical mile) mission. The cruise Mach number was .70 at 10100 meter (33,000 foot) altitude. The improvement resulting from application of the Q fan propulsion system was computed relative to an optimized fuel conservative transport design. The performance improvements resulting from application of ACT technology were relative to the optimized Q fan propulsion system configuration

Evaluation of active control technology for short haul aircraft

An evaluation of the economics of short-haul aircraft designed with active controls technology and low wing-loading to achieve short field performance with good ride quality is presented. Results indicate that for such a system incorporating gust load alleviation and augmented stability the direct operating cost is better than for aircraft without active controls

Allometry of Litter Mass in Bats: Maternal Size, Wing Morphology, and Phylogeny

We examine how litter mass in bats varies with respect to wing loading, an important aerodynamic aspect of flight. From geometric proportions, litter mass should scale to wing loading by an exponent of three. Conversely, analysis of aerodynamic consequences of carrying extra mass suggests that an exponent significantly less than three would be selectively advantageous. Our results show that Megachiroptera and Microchiroptera differ in the relationship between litter mass and wing loading. Litter mass in megachiropterans scales as expected by geometric proportions, whereas litter mass in microchiropterans, as a group, and for individual families, scales as expected if aerodynamic consequences of flight influence litter mass more than size constraints. Thus, selection pressures on reproductive traits appear to differ between the two suborders of bats