Kinematic changes with increased mass

Kinematic changes with increased mass. A, Vertical component of aerodynamic forces balances weight, while the lateral component provides for the centripetal acceleration of the spinning seed. B, As mass increases, the autorotation frequency f1R increases and the coning angle (β) reduces. These changes result in a more vertically oriented and larger aerodynamic force to balance the increased weight, allowing the descent speed V to remain nearly constant

Laser cutter source file for adhesive polyester film weights used in ballasting

Laser cutter (.ai) source file for adhesive polyester film weights used in ballasting

Representative autorotative descent in a Manifera talaris single-winged model

Representative autorotative descent in a Manifera talaris single-winged model, filmed at 500 fps, model is 9.5 mg

Nondimensional aerodynamic parameters versus disk loading

Nondimensional aerodynamic parameters versus disk loading (eq. 3) for all autorotative descents of Manifera talaris models and Agathis australis models and seeds. A, Reynolds number (Re, eq. 1). B, Advance ratio (J, eq. 2). C, Effective lift coefficient (CL,eff, eq. 7). D, Effective drag coefficient (CD,eff, eq. 6)

Laser cutter source file for winged seed models

Laser cutter (.ai) source file for winged seed models

Raw data and R code for plotting

Data and R code to produce figure 2, which gives (a) Percent righting (N=26 birds, number of drops as indicated) and (b) righting mode (N=26 birds, number of successful rightings as indicated), and (c) vertical force production (N=5 birds, except for N=1 at 14 dph; data represent mean ± 1 s.d.) versus age in Chukar Partridge. Righting via roll, as accomplished by asymmetric wing and leg movements, is used prior to 14 dph. Around 9 dph, birds switch to righting via pitch using symmetric wing motions, and vertical force production increases concomitantly

Aerodynamic Characteristics of a Feathered Dinosaur Measured Using Physical Models. Effects of Form on Static Stability and Control Effectiveness

<div><p>We report the effects of posture and morphology on the static aerodynamic stability and control effectiveness of physical models based on the feathered dinosaur, <i>Microraptor gui</i>, from the Cretaceous of China. Postures had similar lift and drag coefficients and were broadly similar when simplified metrics of gliding were considered, but they exhibited different stability characteristics depending on the position of the legs and the presence of feathers on the legs and the tail. Both stability and the function of appendages in generating maneuvering forces and torques changed as the glide angle or angle of attack were changed. These are significant because they represent an aerial environment that may have shifted during the evolution of directed aerial descent and other aerial behaviors. Certain movements were particularly effective (symmetric movements of the wings and tail in pitch, asymmetric wing movements, some tail movements). Other appendages altered their function from creating yaws at high angle of attack to rolls at low angle of attack, or reversed their function entirely. While <i>M. gui</i> lived after <i>Archaeopteryx</i> and likely represents a side experiment with feathered morphology, the general patterns of stability and control effectiveness suggested from the manipulations of forelimb, hindlimb and tail morphology here may help understand the evolution of flight control aerodynamics in vertebrates. Though these results rest on a single specimen, as further fossils with different morphologies are tested, the findings here could be applied in a phylogenetic context to reveal biomechanical constraints on extinct flyers arising from the need to maneuver.</p></div

<i>Microraptor gui</i> from [2], a dromaeosaur from the Cretaceous Jiufotang Formation of Liaoning, China; physical models, and sign conventions.

<p>A, Holotype specimen IVPP V13352, scale bar 5 cm. Notable features include semilunate carpal bones, a boomerang-shaped furcula, a shield-shaped sternum without a keel, uncinate processes on the ribs, unfused digits, an intermediate angle of the scapulocoracoid, and a long tail of roughly snout-vent length. In addition, there are impressions of feathers on the forelimbs, hindlimbs, and tail. B-J, Physical models of <i>M. gui</i>, scale model wingspan 20 cm, snout-vent-length 8 cm. Reconstruction postures, B-I, used for constructing physical models: B, sprawled, after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085203#pone.0085203-Xu1" target="_blank">[2]</a>; C, tent, after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085203#pone.0085203-Davis1" target="_blank">[34]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085203#pone.0085203-Xu6" target="_blank">[58]</a>; D, legs-down, after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085203#pone.0085203-Davis1" target="_blank">[34]</a>; E, biplane, after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085203#pone.0085203-Chatterjee1" target="_blank">[32]</a>. F-I additional manipulations: F, asymmetric leg posture with 9090 leg mismatch ( <i>arabesque</i> ); G, example asymmetric leg posture with 45 dihedral on one leg ( <i>dégagé</i> ), H, sprawled without leg or tail feathers; I, tent without leg or tail feathers. J, test setup; K, sign conventions, rotation angles, and definitions for model testing, after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085203#pone.0085203-McCay1" target="_blank">[10]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085203#pone.0085203-McCay3" target="_blank">[30]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085203#pone.0085203-McCormick1" target="_blank">[31]</a>.</p

Presence or absence of leg and tail feathers can substantially alter longitudinal plane aerodynamics.

<p>Sprawled and tent postures with and without feathers, all coefficients shown versus angle of attack, solid squares with leg and tail feathers, open squares without leg or tail feathers. A, Lift coefficient. Stall occurs at higher angle of attack when leg feathers are present. B, Drag coefficient. Leg feathers increase drag at high angle of attack, improving parachuting performance. C, Lift coefficient versus drag coefficient. D, Lift to drag ratio. Lift to drag ratio is improved slightly without the additional drag and less-efficient lift generation of hind wings. E, Pitching moment coefficient. Without leg feathers, stability is not achieved in either posture. F, Pitching stability coefficient.</p

Asymmetric tail movement (lateral bending) effect on yaw, tent posture.

<p>Baseline tent position (solid square), tail 10 left (open square), tail 20 left (open triangle), tail 30 left (open diamond). The tail is effective at creating yawing moments but at low angles of attack it is shadowed by the body and larger movements are needed (yellow versus red lines).</p