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Da Vinci's Ornithopter Prepares For a Test Flight
Dirak writes "Over 500 years ago, Leonardo da Vinci conceptualized a self-powered flying machine that would achieve both lift and thrust with flapping wings alone and named it the "ornithopter". Hot on the heels of the 100th Anniversary of the Wright Brothers flight, and the recent X prize, a team of scientists from University of Toronto's Institute for Aerospace have taken on this challenge to make Leonardo's dream a reality."
We have one of these toy ornithopters and it flies quite nicely. Its use of a leading-edge rigid spar and loose mylar wing material make the wing form a semi-efficient shape on both the up and down stroke.
Two wrongs don't make a right, but three lefts do.
Back in September, they tried to make it work but it didn't get very far at all...
The proper name to use is "Leonardo", or "Leonardo Da Vinci", not "Da Vinci". That's like referring to someone as "of Dallas".
Probably, but you never know... plus carftsmen of the past had shared secrets which got mostly lost over time (blame wars, plague, etc.) as how to build very light and yet solid structures out of wood (and eventually, stone). Think about european cathedrals. Most of them were made without any blueprint. That's truely wonderful. Re-building a working replica sometimes is the only way to go to get back that knowledge. I once saw a documentary on our Discovery channel's sibbling, about the making of a middle-age catapult. The first real life attempts broke themselves into pieces until they managed to understand archeological evidences and set all ratios back to what they once were, and then put the thing on wheels which were not used to carry the weapon around (as was unanimously beleived), but to handle the recoil. Then, they achieved pretty nice accuracy out of what was thought to be a primitive device.
A television programme (I think it was entitled The DaVinci Challenge) aired on the Australian Special Broadcasting Service earlier this year, in which two teams built and tested DaVinci's ornothopter (and some other machines of his) using materials only available in Ol' Leo's time.
It's a reference to this Magic the Gathering card. For those of you that don't play the game the card is used in several combination plays that can inflict great pain on your enemy, but more often than not it is just a 0/2 for 0 mana cannon fodder.
The FlightGear flight simulator (GPL) has an ornithopter modeled. It uses wind tunnel data and should be quite accurate. Here's a screenshot (38 kB). Start it like so: $ fgfs --aircraft=ornithopter
It is more useful to block those annoying 1/1 creatures. Ever lost a game because of a Scryb spryte?
You don't need to enchant it, as there are other ways to encrease the power such as Tawno's Weaponry.
Just a Tuna in the Sea of Life
(From the previous post...) "The reason nature has adopted the flapping wing is simply because it cannot emulate a shaft unidirctionally rotating in a bearing in a biological structure, so it had to make do."
Au contraire. Mother Nature is one hell of an engineer. I remember reading about the design of bacterial rotary flagellae in Scientific American a few years back, and marvelling at the elegance of the motor.
Here's an article from Wikipedia that describes it pretty well (excerpted below).
The filament is composed of the protein flagellin and is a hollow tube 20 nanometers thick. It is helical, and has a sharp bend just outside the outer membrane called the "hook" which allows the helix to point directly away from the cell. A shaft runs between the hook and the basal body, passing through protein rings in the cell's membranes that act as bearings.
The bacterijjkklellum is driven by a rotary engine composed of protein, located at the flagellum's anchor point on the inner cell membrane. The engine is powered by proton motive force, i.e., by the flow of protons across the bacterial cell membrane due to a concentration gradient set up by the cell's metabolism (in Vibrio species the motor is a sodium ion pump, rather than a proton pump). The rotor transports protons across the membrane, and is turned in the process. The rotor by itself can operate at 6,000 to 17,000 rpm, but with a filament attached usually only reaches 200 to 1000 rpm.
The method employed by an orthithopter to generate lift and propulsive force is very different than what an insect uses. This is how I understand it: because of the small Reynolds numbers or ratio between the aerodynamic forces and inertial forces of the wings, the air seems a lot more viscous to an insect. It doesn't produce lift in a traditional sense that a bird or an airplane does. As its wings flap, the motion generates a vortex and the spinning motion of the air produces low pressure inside the vortex. During each stroke of a wing, the flapping motion of the insect is such that the vortex moves across the upper surface of the wing. This vortex imparts a large pressure differential between the lower and upper surface. At the scale of an insect, the amount of lift produced is much larger than what you could produce by having a stationary wing with an airfoil-type cross-section. But it doesn't efficiently scale up to anything larger than a humming bird, at least not in air. You'd need a denser, probably more viscous gas/fluid. I've seen mineral oil used as a medium to study mechanical equivalents of insect wings since it's density and viscosity lets you slow down the time scale.
I've been to a presentation by the professor in charge of the ornithopter program. They did some amazing research to figure out how to make this concept work. It has to do with correctly coupling the elastic flapping motion of the wings with twisting motion. But unlike an insect, lift is produced by the forward motion of the aircraft, just like in a normal airplane. The thrust is produced by the flapping and twisting motion pushing the air back.
If anybody remembers the movie Birdy, there was a scene early in the movie where the main character lets a elastic powered ornithopter go in a class room. What an awesome site to see that little guy fly.
;]
If you have not seen the movie, I highly recommend it and the soundtrack is based on one of Peter Gabriels better albums.
Regarding UofT project, I hope these guy's succeed. I'm pretty sure that materials have gotten strong and light enough to enable full size models but... very very expensive! I hope they bring a parachute
Which is the reason that you'll see whales flying through the water using their fins. The Reynold's Number is high enough to allow movement using fins, but low enough that lift can be sustained using those same fins.
.8-.9, while carrying a load of several tens of tons of cargo.
For a smaller Reynold's number example, the cuttlefish's method of propulsion is a good one. It uses a long fin and creates a wave-like modeshape using the fin. That wave-like mode transfers momentum very well to the surrounding water because of the scale that the fin operates at. To get a similar effect in air, you'd need a wingspan that is several orders of magnitude longer and with a larger wing area.
And as a side note, Reynold's number is why you see large airplanes (747, A300, C5, etc.) with a large wingspan and relatively thick wings. But they are optimized for flying at 35,000 feet at a certain speed. Whereas if you look at the U2 (spyplane, not the band), or a glider / sailplane, you'll see long thin wings. The longer / thinner wings are much more efficient at creating lift for an equal amount of drag, but they are not the optimum design for flight at 35000 feet and Mach
If you ever get the chance to see footage of a U2 taking off, it's very impressive and I highly recommend it. The thing just seems like it goes straight up!
From the FA..."However, until now, most attempts to fly by flapping wings, either using human muscle or mechanical power have failed." OK, argue "most" with me if you want, but..... There are readily available R/C kits that do just this. I am not talking about those stupid "TIM" birds that you wind up and they flap around like they are having a seizure, I mean a real "R/C ORNITHOPTER". Here is a link to videos of one of the MANY models available. http://www.jgrc.biz/en-us/pg_25.html While the full-size project is definately cool, I think they are overstating it a bit. This design HAS been made mechanically possible well before now.
Repant. Thy end is sheer.
No, the limiting factor with insects is that their oxygen-exchange mechanism doesn't scale well beyond 4-6" (size of the largest beetles), but it doesn't explain how we have fossils of dragonflys with 3' wingspans...
Ostriches adapted to not being able to fly by being able to kick in the head of a lion and run 30-40 mph. They do not have short, squatty legs like an elephant. They do not have hollow bones like flying birds do (but neither do Cornish Cross chickens, you know, the ones we all eat 95% of the time).
Of course, you are assuming that if you scaled the overall size of a mosquito 100x that the rest of the mosquito's body would not also adjust to compensate. Besides, crane flies are pretty big enough (they look like giant mosquitos, but the part about them that sucks are their larvae in your yard).