Friday, January 18, 2013


Forces of Flight (birds)

Lift, Gliding, Flapping, and Drag comprise the basics of flight for birds (or similar) and demonstrate the aspects that result in differences between natural and man-made aviation. The principle of lift is the same as in aircraft design; air travels across the airfoil (above and below), and the difference in air pressure results in upward force and eventual lift of the aircraft. Gliding is based on the same properties of lift, but allows gliders to obtain both a vertical and forward force from the wings since the lift is generated at 90deg to the air flow (gliders are descending so forces are directed at the underside of the airfoil). Flapping is characterized as the motion of wings similar to lift, but rotated to propel the body forward, creating thrust (which counteracts both the drag and weight of the body). Flapping has two stages: the down-stroke which provides the thrust, and the up-stroke which requires adjustment of the wing position to minimize resistance. During the shift between up- and down-stroke, both wing position and angle of attack change to maximize control over the path and speed of flight. Drag affects the flight through multiple methods (frictional, form, lift-induced), each of which is addressed by wing position, angle of attack, and wing shape.



Flight Analysis (Sustained Idle)

Rufous Hummingbird flight analysis in a testing facility. Water and olive oil droplets act as the visible particles to observe changes in particle position/movement (yellow particles represent airspeed) and locations of highest turbulence. Differences in flight types demonstrates possible alternate mechanics for idle sustained flight than propulsion/ascension flight.




Fluid Mechanics (Bat Flight)

Windspeed and friction analysis of the flight of a bat and the wake of typical flight pattern. Notice the form created by the turbulence of the change in air pressure due to the force and motion of the wings.

http://brown.edu/Research/Breuer-Lab/research/batflight.html

Bullet Train and Kingfisher (biomimetics)

Biomimetics used in the development of aerodynamic design, specifically in the re-engineering of bullet trains to eliminate turbulence when passing through tunnels. Original designs featured a fully-rounded front end which results in a pressure differential (sonic boom upon exiting tunnels).

Physics of Bird Flight (diagram)

Variations in Wing-Assisted Incline Running (WAIR) and Controlled Flapping Descent result in a variety of flight types and patterns which vary by species and size.

Wing-assisted incline running (WAIR)

The ability of birds to exploit complex 3D environments through adjustments in the rate, angle, and rotation of their wings and tail results in flight paths that cannot be replicated in traditional man-made flight.

http://jeb.biologists.org/content/214/14/2354.abstract