Artificial Feathers to Reduce Drag?

[Thalass]

I just read this in New Scientist. Seems pretty interesting, though it would be a pain to make and align the number of 'feathers' required for the back of a car.

Here's the link: Fake feathers could take the drag out of flights - tech - 13 April 2009 - New Scientist


Anyone want to try it? hehe

[tasdrouille]

I don't think this have much to do with the feathers themselves. By placing the feathers in the way they did, they effectively altered the shape of the cylinder, making it more like an oval, which obviously have a lower Cd.

[winkosmosis]

Birds have feathers because you can't grow smooth plastic sheets

[aerohead]

PBS Television had a program entitled "Raptor Force" and it got into modern aeronautical engineering's quest to adapt a bird's body-morphing abilities for fighter aircraft.In the show,they attached small closed-circuit television camera broadcast equipment to falcons and owls to get airborne with them.When "looking backwards" during flight,you could see how the feathers behaved during glides and stoops.One thought that grabs you,is that a feather is part of a closed-loop feedback system for the bird.Each feather is mounted in an articulating structure surrounded by nerve endings.During flight,if the bird's angle of attack causes detached flow,the bird can alter it's shape or orientation with respect to the surrounding air mass to regain attached flow.Herein lies the greatest benefit of the feather.It "signals" efficient flight and is constantly relaying real-time data to the flight control portion of the bird's brain.---------------------------- No doubt,bio-mimicry can aid airflow to an extent,but perhaps never to the degree of a living morphable structure.

[Junimrox]

Originally Posted by winkosmosis

Birds have feathers because you can't grow smooth plastic sheets

LOL
maybe some day birds will be made of carbon fiber

[Bicycle Bob]

Any roughness will improve a cylinder, or a golf ball, so the example is spurious. However, there is a lot to be said for adaptive surfaces. Organic fliers seem fond of using attached vortices to extend their performance envelope. Car bodies don't usually have such radical changes in angle of attack. Feathers also have excellent structural advantages, being surfaced with velcro-edged strips that resist tearing, but can be repaired instantly.

[jamesqf]

Originally Posted by winkosmosis

Birds have feathers because you can't grow smooth plastic sheets

Bats, pterodactyls, dragonflies, and more, all with wings that are arguably smooth "plastic".

Borrow a stereo microscope, and take a good look at the small-scale structure of a feather. Then try to figure out how to build something with the strength/weight ratio of a wing primary feather out of a smooth plastic sheet...

[lunarhighway]

a feather is part of a closed-loop feedback system for the bird

usually nature is way ahead of us... the basic shape of a car is no where near as optimized for any such advanced features to be of interest in todays car design.

than again one day maybe....

"feathers" in the broad sense of the word could be interesting to smooth out the underside of the car, especially things like inner wheel wells etc...

[theunchosen]

On short notice I could not find an article that highlighted this, but scientists have already replicated this effect and already use it on airplanes.

The effect is not obvious because you miss it in the confusion of the wings. Mako sharks have a rough surface that has valleys and hills that traps a layer of water against the scales. The water-water drag is 10% less drag than that of smooth surfaces(fiberglass boat hull). They already manufacture the crap it comes in big adhesive sheets that are applied to airplanes along the wings and fuselage.

Feathers aero properties do the same thing trapping a layer of fluid(air this time) against their body to decrease drag. As many have already said feathers also have the ability to manipulate on the fly to take advantage of air currents.

Cars could do this but it would be extremely complex and require lots of processing power. Birds don't usually get the advantage of having other objects moving at the same speed around them unless they are travelling long range in a flock. Cars would be able to take advantage of vacuums created by cars in front of them by flattening out the front to provide a larger surface to attach to the vacuum or foil out when in the lead.

So behind a semi you would look like |> and then otherwise you would look like this <>.

[Otto]

Feathers, fur on otters and seals, etc. also act as compliant wall surfaces, helping to dampen the oscillation of turbulent flow at its source, thereby reducing drag. This per research by Denis Bushnell et al at NASA Langley in the 1980s, with whom I spoke briefly at the time.

Also, some homebuilt airplane guy in Alaska about that time tried an experiment where he says he put fur (coulda been polar bear fur, but I don't recall exactly) on his plane, and reported that it reduced the drag, presumably for the same reasons. He approached the Air Force with this idea, and they told him to take a hike. This per Sport Aviation article at the time.

Perhaps this phenomenon stems from the same concept as the Sinha deturbulator tape, which is claimed to counteract turbulent flow as it begins.

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