Of wingtips and Corvus corax

[raytoews]

I watch Ravens fly, and marvel at them, they fly for fun, unlike most birds which primarily fly for business. Kind of the difference between many commercial pilots and us recreational aviators. I have seen them do rolls, and play with each other by going gear to gear. They have an automatic undercarriage deployment system built in, when they approach stall speed the gear automatically extends.
I particularly like their wingtips, they are like an extension of our fingers splayed out. I assume if natural selection works this has evolved into the most efficient drag reduction.
So why have we not tried this with our airplanes? With some of the supper stiff carbon fibers out there it must be possible to create something like this.

Ray Toews
Fort Vermilion AB
C GRGG (X)
Grumman Cheetah

[mrbarry]

winglets

http://en.wikipedia.org/wiki/Common_...e:Krummi_1.jpg

[raytoews]

I am familiar with winglets, they have been around for a long time, if I recall the Rutan Ezes were one of the first to use them.
I think I understand their aerodynamics, they take that swirling air off the wingtip and reverse it by redirecting and dissipating. ??? I think.
My point is the evolutionary force at work has optimized the ravens wingtips.
There seems to be a difference in the method of wingtip turbulence dissipation between a raven and anything the engineers at NASA or Boeing have come up with.
With modern ridgid carbon fibers could we not duplicate the ravens wingtip?
Has it been tried that I am not aware of?

[raytoews]

The other thing that impresses me about ravens is the CofG range they are capable of. I have seen them takeoff with a substantial bone in their beak. Prey birds like eagles and hawks usually carry their load in their claws near the CofG. A raven usually carries it in the beak, that would be like us hanging our baggage on the tip of the spinner.
Amazing the performance when you have large control movement run be fly by nerve flight controls

[Marc Zeitlin]

I am familiar with winglets, they have been around for a long time, if I recall the Rutan Ezes were one of the first to use them.
I think I understand their aerodynamics, they take that swirling air off the wingtip and reverse it by redirecting and dissipating. ??? I think.
My point is the evolutionary force at work has optimized the ravens wingtips.
There seems to be a difference in the method of wingtip turbulence dissipation between a raven and anything the engineers at NASA or Boeing have come up with.
With modern ridgid carbon fibers could we not duplicate the ravens wingtip?
Has it been tried that I am not aware of?

http://www.icas.org/ICAS_ARCHIVE/ICA...PAPERS/067.PDF

[raytoews]

COOL
Thank you.

Ray

[Louis]

I've been watching ravens most of my life also and they are amazing birds. I've even watched one do loops. Bach made such a big deal about "Jonathan Livingston Seagull", but ravens were already there....maybe there should be a book about an especially aerobatic raven called " Robert Hoover Raven."

One thing I've been wondering: I've watched ravens flying around in ground icing conditions..do ravens (and probably other birds) have deicing? I would think they have enough body heat to keep the ice off, but since I've also watched ravens flying around when it's -40 it seems like losing enough heat through the wing to keep the ice off would cause hypothermia in cold weather. Maybe just flexing the feathers works as deice boots....Louis

[Anders]

One thing I've been wondering: I've watched ravens flying around in ground icing conditions..do ravens (and probably other birds) have deicing? I would think they have enough body heat to keep the ice off, but since I've also watched ravens flying around when it's -40 it seems like losing enough heat through the wing to keep the ice off would cause hypothermia in cold weather. Maybe just flexing the feathers works as deice boots....Louis

So, uh, after a little reading, it appears that ravens have a pretty complex system of temperature regulation, including a system for temperature distribution that could be considered de-icing. Here is a small excerpt here from an excellent Wikipedia article on Raven Physiology:

Common Ravens occupy a widespread geographical range and are found in many different habitats, including tundra, seacoasts, cliffs, mountainous forests, plains, deserts, andwoodlands.^[1] Due to such a diverse habitat, this species is exposed to various temperatures and amounts of precipitation. Individuals that exist in warmer, drier environments have lower basal metabolic rates than organisms inhabiting non-arid areas. Physiologically, a reduced metabolic rate decreases endogenous heat production to prevent evaporative water loss, or more simply evaporation, and conserve energy in an environment with limited resources. A reduction of total evaporative water loss consists of decreases of both respiratory and cutaneous evaporation. In contrast, Common Ravens living at higher latitudes in temperate regions experience high basal metabolic rates. A higher metabolism is related to increased thermogenesis and cold tolerance.^[3]
In relation to temperature and precipitation, Common Ravens are exposed to changing seasons with climate extremes. Within the Common Raven species, the degree of climatic seasonality is related to the magnitude of fluctuations in basal metabolic rate and total evaporative water loss.^[3] For instance, populations living in Alberta are subjected to both extremely cold temperatures in the winter and very hot and dry weather during the summer months. Furthermore, the Common Raven is not known to migrate long distances to avoid the winter season, so it is required to regulate and cope with the environmental conditions.^[1]
Habitat variation often leads to changes in activity levels. Ravens engaged in flight are considered metabolically active. During periods of flight, the cells require more oxygen, and the heat generated must be dissipated to avoid hyperthermia.^[3] In response, the Common Raven experiences an increased heart rate and cardiac output.^[4] Another method used by many species of birds to regulate thermal conductance is by internally adjusting blood flow through shunt vessels. More specifically, arterial and venous blood vessels are organized to bypass the countercurrent heat exchange occurring in the upper portion of a bird’s legs. Countercurrent heat exchange involves arrangements of blood vessels that allow heat to transfer from warm arterial blood to cooler venous blood travelling to the body’s core. Through this mechanism, arterial blood remains warm before reaching the body’s periphery.^[3]

Pretty fascinating stuff.

[Louis]

Very interesting! Thanks for sharing that, Anders.

[mrbarry]

notice:
the optimal configuration of multiple winglets shown in article ref: above and actual as shown in image of bird in descent

egggzact