Stories tagged aerodynamics
I guess there is some science involved with this post (physics, marine biology, aerodynamics, fight or flight response, etc). I kind of like it.
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Dragonfly wing: Its structure is aiding wind-power researchersCourtesy Mark RyanResearchers in Japan are studying the wing structure of dragonflies to help improve how micro wind turbines perform during high winds. Micro turbines are small, affordable energy converters that can be used in both urban and rural settings where giant turbines would be too expensive, too large, and too impractical. Micro turbines can be set up relatively easily in configurations of a single unit or as a bank of several units, and the energy generated can be stored in batteries.
They work on the same principle as the large turbines, but can generate power in wind speeds as low as 4 or 5 miles per hour. One fallback, though, is their generators can get overloaded when hit with high storm winds, producing more energy than the system can handle. Large turbines solve this problem by tilting their propellers - either by computer or otherwise - and adjusting their rotation speed. But that kind of technology just isn’t affordable with micro turbines.
That’s where studying dragonfly wings comes in. Aerospace engineer Akira Obata of Nippon Bunri University in Oita, Japan wondered how dragonflies were able to remain stable in flight at low speeds. He placed a plastic model of a dragonfly wing into a large tank of water laced with aluminum powder and videotaped the flow patterns. He noticed that as the water flow slowed down vortices arose on the wing’s surface that allowed the water to pass over the wing at the same speed, thus keeping it stable. But when water flow sped up the wings aerodynamics performance decreased.
So, Obata developed an inexpensive paper micro turbine with similar “dragonfly wing” bumps on its surface and it did just as he hoped. When air speeds flowing over the turbine wing increased between 15 and 90 mph, rather than speeding up its rotation and overwhelming its battery, the micro turbine curved into a conical shape that stunted rotation and kept power generation low.
New Scientist story
CNBC story on homemade micro turbine
Make your own micro turbine
Holy cow, this video has everything: feats of engineering, seemingly impossible flight, scientific explanations, and instructions on how to do it yourself!
It's unclear who is actually behind it, but someone at Sciencetoymaker.org has posted a video of an amazing paper glider that is so aerodynamically efficient, you can "surf" it on a wave of air generated with your hands. I can't put into words how cool this is. Check out the video, and hit up the main site for the .pdf of the template.
Kites over Lake HarrietCourtesy Mark RyanOver the centuries, kites have been used for ceremonial purposes, military tactics, scientific experiments, and of course just for fun. The actual origin of kites is sketchy. Some historians claim the islanders of the South Seas first used them to catch fish. But others say kites were first invented in China nearly 2500 years ago. 
Steady as she goes.: Kids love flying kites.Courtesy Mark Ryan
Some fanciful kitesCourtesy Mark RyanWhatever the case, kites are fun to fly. Yesterday, the 10th Annual Lake Harriet Winter Kite Festival took place on Lake Harriet in Minneapolis. Despite the frigid temperatures, it was a beautiful day for the event. A big crowd was present when I was there, and there were some colorful as well as unusual kites in the air. And it’s not just a matter of slapping a sheet of old newspaper to a couple slats of balsawood and adding a tail and some string, kite-flying involves a lot of science.
It ain't rocket science: But keeping a kite aloft takes more than just a good breeze.Courtesy Mark RyanAnyway, the event was sponsored by several organizations, including the Minneapolis Parks and Recreation Board, and the Minnesota Kite Society. 
Successful kite launch: Up, up, and away!Courtesy Mark Ryan
If you want to get involved in kite-flying yourself, there’s a ton of information on the Internet to get you started. I’ve linked to a few of the better ones I found including the site for National Kite Month, which runs this spring from March 27th to May 2nd.
Come on now; get off that couch, join in the fun, and go fly a kite.
Using Kites to Study Aerodynamics
World’s largest kite plan archive
PBS Challenge: How does a kite fly?
The Kite Society (UK)
Kite Study for Children (includes some history)
National Kite Month
Off we go!!: A bundled kite-flyer gives her aircraft a good boost at launchCourtesy Mark Ryan
All sorts of kitesCourtesy Mark Ryan
Giant bear kite dominates the skyCourtesy Mark Ryan
Lake Harriet Winter Kite Festival: Minneapolis, MNCourtesy Mark Ryan
The sky's the limit!: But probably not for this group; they look more like posers than actual paper airplane aficionados.Courtesy toolmantimHere’s an article about a paper airplane virtuoso who’s trying to break the world’s record (held by himself) for keeping a hand-launched paper plane in the air. Engineer Takuo Toda of Japan not only wants to beat his old record of 27.9 seconds – set last April in Hiroshima – he’s also set his sights on achieving the nearly impossible - breaking the 30 second barrier. Actually, the record time of 27.9 seconds should require an asterisk in the record books since it was set using a paper plane with tape on it. The paper-only airplane record – using a single sheet of uncut paper - is 26.1 seconds, and Toda holds that one, too. This guy seems to be the undisputed king of paper airplanes, but I'm sure somebody out there can show him a thing or two. Check out some of the links below and maybe it can be you.
MORE ABOUT PAPER AIRPLANES
More about paper airplane aerodynamics
Build your own paper airplane (by former record holder Ken Blackburn
Build the best paper airplane
How to build 10 paper airplanes with animated instructions no less
Even more paper airplane designs
Fluid flow separation: The fluid flow becomes detached from the surface of the object, and instead takes the forms of eddies and vortices.Courtesy jaganath
Fluid flow separation explained with mathematics in 1904
In 1904, Ludwig Prandtl, considered the father of modern aerodynamics, derived the exact mathematical conditions for flow separation to occur, but only in two dimensions for steady flows.
Unsteady fluid flow in three dimensions explained with mathematics in 2008
A century later, George Haller, a visiting professor in the Department of Mechanical Engineering at MIT led a group that explained the mathematics behind unsteady separation in two dimensions. This month, his team reports completing the theory by extending it to three dimensions. Papers on the experiments and theory are being published in the Sept. 25 issue of the Journal of Fluid Mechanics and in the September issue of Physics of Fluids, respectively. Haller's coauthors are Amit Surana, now at United Technologies; MIT student Oliver Grunberg; and Gustaaf Jacobs, now on the faculty at San Diego State University.
Fluid mechanics theorists are excited
The equation will forever change the face of advanced fluid dynamics and will have a profound impact on many industries, including the aerospace and automotive industries. This quote from Daily Tech Review shows that this breakthough has theorists in fluid mechanics excited;
The new work -- if it survives the extensive peer review that is to come -- will likely go down as the greatest scientific advance of the decade. The research has already survived a strenuous initial round of peer review.
Equally important, this month Thomas Peacock, the Atlantic Richfield Career Development Associate Professor and his colleagues report important experimental work verifying the theory.
"This is the tip of the iceberg, but we've shown that this theory works," Peacock said.
Fluid dynamics makes a difference
Understanding how surfaces effect how an object flows through a fluid (including air) can make big differences in maximizing performance. Did the new swimsuits make a difference in breaking world records in Olympic swimming competition? How about the surfaces of baseballs, golf balls, and tennis balls? The effects on miles per gallon for autos and airplanes can save millions (billions?) of dollars.
Source: MIT News
There has been much hype lately about the ethics of chromosomal testing during the Bejing Olympics. Rather than sending a man to compete as a woman (as the Germans did in the Berlin games),
An ostrich going for the goldCourtesy swh they should have entered an ostrich or perhaps a rhino. Check out the link above to read about high performing animals that would give our athletes a run (or swim) for their money.
A swarm of humans: The sky is full of human gliders in the flying-squirrel-like outfits. The winged suits are the newest trend in sky diving, giving jumpers the chance to glide at up to speeds of 140 miles per hour.Courtesy Matt HooverWorking on the museum floor the other day, one of the volunteers in my gallery was telling me all about human gliding. He’s big on aviation and had some interesting stuff to share on things he’s heard about and seen (but not actually done).
Unfortunately, I wasn’t able to take any notes at the time, but it got me curious enough to Google around and learn more about human gliding. It appears to be just the thing for the sky-diving veteran who’s looking for a bigger adrenaline buzz.
How does this work?
The wingsuit that human gliders wear essentially turns them into a parachute. The flaps between the wearer’s limbs create an airfoil that generates lift as they inflate with air. Gliders can then manipulate their bodies to control the direction and speed of their descent. Jumping from a moving aircraft like an airplane or helicopter also gives the human glider forward speed that translates into lift potential which slows down the fall rate of gliders and gives them a higher glide ratio.
Here’s an awesome YouTube video of a human glider in action. (Warning: The video itself is unobjectionable, but the comments posted to YouTube contain profanity and other strong language.)
Human gliders, when keeping their bodies parallel to the horizon, can reach speeds of 110 to 140 miles per hour. Many human gliders, however, find it a bigger challenge to see how slow they can glide while maintaining their aerodynamics, sort of, but not completely like, stunt pilots stalling out their engines when they’re doing tricks. Some human gliders have slowed themselves down to speeds as low as 25 miles per hour and have lived to talk about it. A more conventional slow speed, however, is about 60 miles per hour.
A closer look: From above, here's a closer view of what's involved with human gliding.Courtesy Matt HooverWhile it’s still a pretty new technology to be used in the sky diving realm with experiments going back about 10 or 15 years, man has been striving to glide through the air for ages.
In the modern era, between 1930 and 1961 there were 71 reported deaths of people attempting to glide or fly with wings attached to their bodies. There were also four successful flights in that same time.
And it appears that human gliding advancements aren’t going to hit the wall any time soon. Experiments are now underway in attaching jet burners to the shoes of human gliders, giving them more thrust and speed to play around with in the skies.
It should go without saying, but nevertheless, don’t try this at home kids, Jackass actors or any others who are easily tempted to display poor judgment. Human gliders are very experienced skydivers who have studied up on this type of aerodynamics.
That all said, is this something that you’d want to try? Share your thoughts here with other Science Buzz readers.
Here are some links if you’d like to learn more about human gliding.
What every budding young physicist should know. From Popular Mechanics.
