'First-ever' flight of robotic ornithopter announced Famous crazycraft company Aerovironment has won a $2.1m contract to further develop its robotic "Nano Air Vehicle" (NAV), which flies and hovers using flapping wings like a hummingbird. The company has also released a video of the innovative craft in test flights. According to Aerovironment, the fluttering NAV achievement …
I've got something like that at home, cost me £14.99. It's a miniature R/C helicopter. I'm not sure the development of flapping-wings robots is all that useful when rotors work very nicely.
Isn't this the equivalent of somebody coming out with a car with legs than runs down the road? Here's a thought: you don't see many wheels in nature, but I don't know of any creatures that can outrun even the cheapest of nasty car tat clogging up our roads.
Paris becase even she would know better.
Efficiency
When the Reynolds number his high, the fluid flow becomes turbulent, wasting energy
When the Reynolds number is small enough, you have laminar flow, in which all the energy is used towards your goal.
That's why a big, low rpm fan is much more effective and quiet than a small, high rpm one.
Is they're better able to survive collisions? I saw wildlife on one or something about butterflies, and how they can still fly when their wings are torn to shreds, perhaps there is an advantage there.
Also, if they can make one this size that works, they could potentially make it smaller still. I'd guess that mini helicopters couldn't be shrunk to the size of a blue bottle and still work? Although blue bottle sized helicopters would be very cool toys.
As far as I know, the DelFly of the Delft University of Technology (and another project by David Lentink of the Delft University and Wageningen University) was earlier (maybe even the first): http://www.tudelft.nl/live/pagina.jsp?id=861eb007-c9e5-4f7e-a9b3-a81d36b3a32f
See also http://www.youtube.com/watch?gl=NL&hl=nl&v=rmf3qWqox7k at around 5:50
But probably since it didn't happen in the States, it did not exist.
but I'd have to agree that aside from the academic point of view, the benefits are dubious.
The only reason nature uses flapping based propulsion systems is that nature cannot produce an infinately rotational ball joint.
Even the helicopter, which beats the laws of physics into submission, rather than working with them like the plane wing is vastly more efficient than birds at powered flight.
This is down to the fact that rotors, propellers and jet turbines can continuosly rotate in one direction. Birds and insects lose a tremendous amount of energy each time their wing reaches the end of its travel, as they have to then put twice that energy back in to change its direction.
I'm also struggling with the concept of noise reduction. Surely anything that flaps its wings at such a high bmp is going to generate an enormous amount of noise? If you think about it, the wing is a relatively flat surface moving back and forth at a high frequency - just as the surface of a speaker cone does.
We've all heard the disproportionate amount of noise something as tiny as a blue bottle generates? And the blue bottle has no engine noise.
As with most DARPA projects I read about though, I love it! Practical? Nah! Fascinating? hell yeah!
I would certainly be interested to hear more about wing resiliancy in comparison to rotors though. I suppose it depends on the makeup of the wing itself, more than anything else.
Yes, but now take your average car off-road and compare its performance up hill and down dale compared to a horse. There's a reason cars do well in that contest: it's 'cos the level playing field we call a road is designed for them to work on.
Nice thing about leggy devices/creatures is that they DON'T need a smooth, flat surface to operate on.
As for the ornithopter/helicopter question, I imagine it has to do with the viscosity of air at smaller scales. Same reason it's easier to fly at the scale of a fly (indeed for really tiny creatures the challenge would be staying on the ground) than it is at the scale of a jumbo (pachederm or jet)
I'm no aeronautical engineer, though, so I couldn't say for sure.
"Future versions of the bugthopter are expected to be able to "perch" in suitable locations, relaying sound and video back to their controllers up to a kilometre away, AS they also drop off very small payloads such as tiny clouds of anthrax..."
There, fixed that for ya....
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