An approximate theoretical formula for the distribution of aerodynamic load over arbitrary thick wings in incompressible flow is developed by combining three-dimensional results from thin-wing theory with two-dimensional results from thick-aerofoil theory. The formula is applied to two wings of identical planform, with 60 degrees trailing-edge sweepback and differing aerofoil thickness, which h...

Hummingbirds are specialized hoverers for which the vortex wake has been described as a series of single vortex rings shed primarily during the downstroke. Recent findings in bats and birds, as well as in a recent study on Anna's hummingbirds, suggest that each wing may shed a discrete vortex ring, yielding a bilaterally paired wake. Here, we describe the presence of two discrete rings in the w...

Wandering is a typical feature of wing-tip vortices and it consists in random fluctuations of the vortex core. Consequently, vortices measured by static measuring techniques appear to be more diffuse than in reality, so that a correction method is needed. In the present paper statistical simulations of the wandering of a Lamb-Oseen vortex are first performed by representing the vortex core loca...

In the leg and wing imaginal discs of Drosophila, the expression domains of the homeobox genes aristaless (al) and Distal-less (Dll) are defined by the secreted signaling molecules Wingless (Wg) and Decapentaplegic (Dpp). Here, the roles played by al and Dll in patterning the legs and wings have been investigated through loss of function studies. In the developing leg, al is expressed at the pr...

By combining optical triangulation with the comb-fringe technique and dual-channel telemetry, wing kinematics and body attitudes accompanying muscle activities of free-flying male hawkmoths were recorded synchronously when they performed flight manoeuvres elicited by a female sex pheromone. The results indicate that the wing leading edge angular position at the ventral stroke reversal, which ca...

In this paper, we explain and explore the idea that knowledge is similar to mass in physics: similarly to how mass curves space-time, knowledge curves the corresponding knowledge space. 1 Knowledge Geometry How to detect that two objects are different? Let us start with the following sample situation. To observe wild parrots, an ornithologist sets up a feeder. Every morning, a parrot appears, a...

This report presents stereo image theory and the corresponding image processing software developed to analyze stereo imaging data acquired for the wake-vortex hazard ight experiment conducted at NASA Langley Research Center. In this experiment, a leading Lockheed C-130 was equipped with wing-tip smokers to visualize its wing vortices, while a trailing Boeing 737 ew into the wake vortices of the...

Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle of attack without stalling. Instead, they generate an attached vortex along the leading edge of the w...

The morphology and kinematics of a flying animal determines the resulting aerodynamic lift through the regulation of the speed of the air moving across the wing, the wing area and the lift coefficient. We studied the detailed three-dimensional wingbeat kinematics of the bat, Leptonycteris yerbabuenae, flying in a wind tunnel over a range of flight speeds (0-7 m/s), to determine how factors affe...