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Jesus Zykov
Jesus Zykov

The Gliding Flight John M Collins Pdf 13

For over a thousand years after this, paper aircraft were the dominant man-made heavier-than-air craft whose principles could be readily appreciated, though thanks to their high drag coefficients, not of an exceptional performance when gliding over long distances. The pioneers of powered flight have all studied paper model aircraft in order to design larger machines. Leonardo da Vinci wrote of the building of a model plane out of parchment, and of testing some of his early ornithopter, an aircraft that flies by flapping wings, and parachute designs using paper models. Thereafter, Sir George Cayley explored the performance of paper gliders in the late 19th century. Other pioneers, such as Clément Ader, Prof. Charles Langley, and Alberto Santos-Dumont often tested ideas with paper as well as balsa models to confirm (in scale) their theories before putting them into practice.[citation needed]

the gliding flight john m collins pdf 13


In the case of scale performance and scale models, the modellers intent will define the type of aerofoil section chosen. WWI biplanes, if designed for flight performance, will often have curved-plate aerofoils, as these produce a highly cambered surfaces and Coefficient of Lift (Cl) for low gliding airspeeds. WWII monoplanes will often have very scale-like sections, though with increased trailing edge droop to improve camber in comparison with scale counterparts.

It is possible to create freestyle versions of paper aircraft, which often exhibit an unusual flight path compared to more traditional paper darts, jets and gliders. Another propulsion technique, creating high launch velocities, involves the use of elastic bands for "catapults". Walkalong gliding involves the continuous propulsion of paper airplane designs (such as the tumblewing, follow foil[10] and paper airplane surfer[11]) by soaring flight on the edge of a sheet of cardboard.

Flap-gliding performance analysis using the altered equations from Pennycuick [58] also provide a solution to the problem of long distance travel in giant pterosaurs, which otherwise would seem to be above the size limits for sustained flapping flight. For Quetzalcoatlus, using the narrow planform of Chatterjee and Templin [19], the estimated best glide speed is 13.3 m/s, and the speed for minimum sink rate is 8.80 m/s. If Quetzalcoatlus was able to work under anaerobic power (see below) to climb out for one minute after launch, this minimum sink speed would provide over a half kilometre of range to reach an external source of lift. However, the situation is more favourable with heavier body masses because it provides substantially more total muscle power and much greater glide speed once the animal begins soaring. Under the broader wing shape of Witton [24], the expected best glide speed for Quetzalcoatlus is 24.9 m/s, and the minimum sink speed is 16.3 m/s. The minimum sink speed would therefore provide close to a kilometre of distance under a one-minute burst, minus distance lost to climbout altitude gain. However, most soaring animals today fly at their minimum sink speed when using thermal soaring and certain forms of shear lift [58], [66]. The maximum range speed may be a more reasonable estimate of the climbout velocity, especially for an animal trying to reach external lift sources. Assuming that Quetzalcoatlus carried mostly anaerobic muscle in its flight muscle mass, as predicted by Marden [23], and using the maximum power output of anaerobic avian muscle ([67] - a conservative estimate, as other diapsids produce more relative power from anaerobic muscle), the expected maximum range speed under the Witton [24] morphology is 48.3 m/s with a climbout altitude gain of 1 m/s. Taken alone, these figures indicate a one-minute burst range of 2.88 km. Of course, considerable time and power would be required to accelerate to the extremely high maximum range speed, but even with those considerations, the range to external lift under an aerobic burst would likely exceed 1.5 km.

Additional issues with proportional differences are found when specifics of flight are considered. Flapping frequency, the crux of the Sato et al. argument for giant pterosaur flightlessness, does not simply differ with mass or wingspan: modern birds demonstrate that span, body mass, and wing area, and relative muscle fractions can influence flapping rates considerably [58]. Thus, even among modern birds, applying universal limits of flapping frequency (and its subsequent influence on flight capacity or launch ability) is nearly impossible. In fact, flapping frequency scales to the 3/8 power of body mass if wing area and span are generated as separate scaling terms [58]. A migrating bird, for example, flaps more rapidly at the beginning of a migration than at the end (as its mass declines [66]). However, wing area and span correlate with body mass when compared across species [110], which means larger bird species do tend to flap more slowly than smaller taxa, but only when there is a high degree of geometric similarity between the comparison taxa (even then, the relationship is most applicable for continuous, steady state flapping). For example, while the large procellariiform taxa used in the Sato et al. [17] dataset are running launchers with low flapping frequencies, similarly sized burst flyers, such as wild turkeys, can launch vertically from a standstill, and flap rapidly [67]. This highlights an additional problem in deriving pterosaur performance from the scaling of flapping capacity in a specific group of birds: muscle physiology is variable among taxa and also scales with size [23]. It is very reasonable to think that large pterosaurs might have utilized relatively large fractions of high power fast oxidative or fast glycolytic muscle fibers (Cunningham, pers com) and, as such, the burst performance of large pterosaurs might have exceeded that seen in many bird species. Furthermore, there is no reason to presume that giant pterosaurs flapped continuously for long periods of time: our flap-gliding analysis suggests the flight muscle capacity of giant pterosaurs was utilized primarily for launch and climb out, with long-distance flight sustained mostly by external energy sources (i.e. unpowered flight sustained by soaring mechanisms, such as ridge shears and thermal columns).

The clade of Natricinae and Dipsadinae is weakly supported as the sister group (Figures 1, 25, 26, 27, 28) to a clade containing Sibynophiinae [181] + (Colubrinae + Grayiinae). The subfamily Colubrinae is weakly supported; we find that the colubrine genera Ahaetulla, Chrysopelea, and Dendrelaphis form a strongly supported clade that is weakly placed as the sister group to the rest of Colubrinae, which form a strongly supported clade (Figure 25). This clade was also placed with Grayiinae or Sibynophiinae in many preliminary analyses, rendering Colubrinae paraphyletic. This group of three genera has been strongly supported in the past, and only weakly placed with Colubrinae [41, 44]. It is possible that future analyses will reveal that the clade of Ahaetulla, Chrysopelea, and Dendrelaphis is placed elsewhere in Colubridae with strong support, and thus merit recognition as a distinct subfamily (Ahaetuliinae). A notable feature of this clade is the presence of gliding flight in most species of Chrysopelea, less-developed non-flight jumping with similar locomotor origins in Dendrelaphis, and homologous glide-related traits in Ahaetulla[184].

Be that as it may, in addition to A. junius, an aeshnid, at least four libellulid dragonflies are regular and often prominent migrants: Tramea lacerata (Black Saddlebags), Sympetrum corruptum (Variegated Meadowhawk), Pantala hymenea (Spot-winged Glider), and P. flavescens (Wandering Glider). The first three of these species have not been studied carefully. Corbet and Eda (1969) found that T. lacerata was present in some numbers among migratory or pre-migratory aggregations of A. junius at Point Pelee and elsewhere in southern Ontario in late summer. They are also frequent among A. junius aggregations at Cape May, New Jersey, and have been observed apparently setting off across the Delaware Bay at this site. The emergence pattern of T. lacerata in Indiana was similar to that of A. junius except for the absence of the small, early spring peak (Wissinger 1988). These data suggest that its behavior and migratory strategy may be similar to those of Anax. All Tramea spp. appear to be physically adapted for gliding flight, and thus potentially for migration, by virtue of their broadly expanded hindwings, and extreme vagrancy [e.g., T. calverti, in the Northeastern United State (Soltesz 1992)] and large swarm migrations in the tropics have been recorded [e.g., T. basilaris, in Africa (Dumont 1977; Pinhey 1979)].


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