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Birds Give a Lesson to Plane Designers
Roland Piquepaille points out a news release from the University of Michigan where researchers are looking to birds and bats for insights into aerospace engineering. Wei Shyy and his colleagues are learning from solutions developed by nature and applying them to the technology of flight. A presentation on this topic was also given at the 2005 TED conference. From the news release:
"The roll rate of the aerobatic A-4 Skyhawk plane is about 720 degrees per second. The roll rate of a barn swallow exceeds 5,000 degrees per second. Select military aircraft can withstand gravitational forces of 8-10 G. Many birds routinely experience positive G-forces greater than 10 G and up to 14 G. Flapping flight is inherently unsteady, but that's why it works so well. Birds, bats and insects fly in a messy environment full of gusts traveling at speeds similar to their own. Yet they can react almost instantaneously and adapt with their flexible wings."
Current aircraft performance is limited by what the occupants can survive. Try to roll a human at 5,000 degrees per second and things would get messy.
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a barn swallow, yes, but an African swallow...
Submarine designers look to fish for ideas on how to move in water.
So does this mean we will soon of ornithopters to defend our spice from the evil Harkonnen?
I'm sick of following my dreams. I'm just going to ask where they're goin' and hook up with 'em later.
(...and what if you're allergic to feathers? )
Quo usque tandem abutere, Nimbus, patientia nostra?
I hate commenting on another annoying stupid Roland article.
.. what's up with that?
Birds and insects have very low mass. As mass increases components have deal with more stress etc.
Post another annoying stupid Roland article when birds flying at high speeds weigh as much as an aircraft (or even a human) and then we'll see how they handle things.
Btw, I could have sworn i saw the "ohnoitsroland" tag and then it disappeared
Perhaps they can roll that fast, and take that many G's, because that's what they have done for thousands (if not millions?) of years. Their bodies have adapted to it, as they do it almost 24/7.
And haven't we already used bernoulli's principle watching birds, and applied that to planes, getting us in the air in the first place. Has it really taken us this long to realize that we can learn how to fly better from watching the things that fly naturally every day?
They do make a point about the roll rate, but a Skyhawk is much more useful for migrating coconuts. An African swallow could carry one coconut at most, but they are non-migratory, so it is uncertain what sort of range they would have. European swallows are generally thought to be unable to carry even one coconut, unless two of them carried it together, but that increases the risk of mid-air collisions.
A Skyhawk, on the other hand, could carry a large number of coconuts. However, unlike with the swallows (where the main issue is not the grip but the weight ratios), the Skyhawk would be limited by the number of coconuts that could be attached. The Skyhawk is an attack aircraft with a payload of close to 10,000 lbs, which would make for a lot of coconuts. But, the only reasonable place to attach large numbers of them without causing aerodynamic interference would be the wing pylons, where the bombs usually go. If they were to fit, these coconut packages could not be much bigger than the bombs. As there are only five hardpoints, I can't imagine there being room for more than about 50 coconuts.
Still, this is a significant improvement over the swallows, and if you had to choose between the two, the Skyhawk would be a much better choice for migrating coconuts into temperate climes. Of course, something like a C-17 would be even better, but those have an even lower roll rate.
In addition, a bird's head is inline with its body, while pilots sit up and require g-suits to force blood back up into their heads. I wonder what forces the pilots could withstand if they piloted in a prone position, though I can't imagine that being very comfortable.
It must have been something you assimilated. . . .
Sometimes they come back.
Roland is off in bogosity land, as usual. The wingspan of a barn swallow is about 0.3m. The wingspan of an A-4 Skyhawk is 8.1m, which is 27x larger. So, scaled for size, an A-4 Skyhawk actually has about 4x the roll rate of a sparrow.
Historically, aircraft that looked or worked like birds have been spectacularly unsuccessful. Little ornithopter UAVs do work, but the ornithopter concept does not scale up well.
I can't remember the source, but several years ago, a researcher in his twenties saw how owls' wingtips point upward on their downstroke. This cuts down on vorticies at the wingtips, making for a more efficient and quiet flight.
Airplane designers then took that idea and applied it to most commercial jets you see today.
This is really amusing, but least I laugh to hard allow me to enlighten some...
The mighty Peregrine Falcon, THE fastest animal in the skies, bar none, have been clocked in dives exceeding 200mph, with radar. Now that is pretty damn fast for anything made of bone, muscle and sinew and covered in something as delicate as feathers. But one has to examine the actions of the animal when it accomplishes these seemingly impossible feats of speed.
Fist of all, much like the famous ( or infamous depending on your POV, especially if you were a pilot in the early very underpowered versions ) F-14 Tomcat Naval Jet Fighter, it makes maximum use of variable wing geometry. When a Peregrine stoops ( the technical term for diving from altitude in the bird world ) its 39 to 43 inch wings fold in very tightly making the outline of the bird look pretty like a "W", leaving just enough airfoil hanging out to effect control. This reduces stress on the main wing spar ( their bones and joints ) by a huge margin thus allowing it to accomplish this feat without tearing its wings off.
Now I don't have an actual measurement of their wing span in a full speed stoop, but from photo's I estimate that it reduces wing span by a good 75% or more. The area of the wing that would comprise the distance between a human elbow and the tips of our fingers goes parallel to the body and the upper wing ( the area from a human shoulder to the elbow ) then are pulled in close to the head, further reducing wing span.
Transition from this "clean" configuration to a "Dirty" configuration after either missing or hitting its prey can be quite rapid and causes the bird to bleed off speed at a very high rate. A Falcon cannot make a "pylon" ( a turn in an airplane in which one rolls the airplane from straight and level flight by nearly 90 degrees and then applies maximum UP elevator ) turn, the force on the wings would quickly overcome the bone, tendon, muscle and joint strength. Now this is not to say the are not maneuverable in a stoop but as you would surmise their maneuverability is greatly reduced at speed. Another very interesting feature of the bird is its nostrils. Small bony tubercles in a falcon's nostrils guide the air and shock wave to prevent over pressuring the lungs and giving the bird the ability to breath while diving.
so while looking to nature can be inspiring for aeronautical design there are very real limitations in duplicating the ability of a bird with mechanical devices. Another instance would be the original Wright Flyer. It did not have ailerons, it used what is called "Wing warping" which is what birds do, but it was found to be quite impractical since the amount of wing warping required to provide the same effectiveness as a bird required that the wings be so flexible to the point of losing to much strength. Now birds do Wing warping one better as they can not only warp their wings but they can dip a wing, decrease span, warp, move their tail in all axes, and do this all at the same time, providing maneuverability that airplane designers can only dream of.
On whales and submarines. If it were not for the requirement that we a) Keep the water out of the people tank and b) be able to stay submerged for months on end, and c) carry weapons that are stand-off capable, perhaps a Blue Whale would be a decent model to study in submarine development, but not as much as one would think. One must remember that a whale of any kind is a completely articulated bit of construction. It can bend and twist in any direction thus altering its hydrodynamic profile at will. Careful study of its means of propulsion reveals that it is a "whole body" movement, not simply a movement of the flukes in an up and down motion. It was also discovered some time ago that whales overcome friction in the water by way of their blubber. Careful examination revealed that hydrodynamic pressure is relieved by the blubber and skin actualy undulating in concert with the pressure waves to facilitate their movement dow
Hey KID! Yeah you, get the fuck off my lawn!
Birds Give a Lesson to Plane Designers
By crapping on their freshly washed cars?
Shop as usual. And avoid panic buying.
Guess what those "inert bombs" were
[oh, and to answer your question: empty weight is about 11000 lbs; max takeoff weight is 24500 lbs.]
Sub designers, aircraft...cars...chairs...these guys/gals are supposed to have studied things like fish, birds, trees and insects for reasons why, and why not, long before they were hired to actually build things.
True, but it might be noted that we made very little progress in flying until some people gave up on trying to mimic birds, and tried other approaches. The first actual "flight" by humans was in the early 1800s, with hotter-than-air balloons. Then around 1900, a few experimenters started to get the hang of wings, and figured out that what worked was to separate the lift generation from the propulsion. Nature never came up with this scheme, but it's technically easier (if you know how to make a rotary motor or a jet engine) than nature's scheme of using wings for both functions.
Similarly, submarines look superficially like fish, but don't really work the same way. Fish use their fins for both steering and propulsion, while submarines use fins only for steering, with a propeller for propulsion. The similar shapes are only for streamlining, which does work the same for everything that needs it.
Usually, nature's solutions to problems are good models. But in cases like fish and birds, it has turned out to work better to give up on them and work from first principles. We're only now starting to produce machines that fly and swim like birds and fish, and they are little more than toys. Our non-natural solutions have turned out to work better for our purposes than what nature found.
We might also note that nature did discover a rotary motor, in the form of bacterial flagellae. We even have them in some of our cells. (Trivia question: Which cells are those?) But nature never figured out how to adapt them to larger, multi-cellular organisms. Maybe on some other planet, but not on this one. Nature also discovered jet propulsion, and uses it under water but not in the air. We know how to do both of these things on a larger scale, and we have used them to solve problems in ways that the evolutionary process hasn't found.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.