In other words...
Owls are quiet. If we can copy their methods then our machines can be quiet too.
Topflight boffins say they may be able to plumb the secrets of silently-flying owls and use them to make all sorts of wing and propeller machinery - planes, helicopters, wind turbines, even submarines - much quieter than they are today. "Owls possess no fewer than three distinct physical attributes that are thought to …
Owls are quiet. If we can copy their methods then our machines can be quiet too.
>then our machines can be quiet too.
But then we would have to add a noise generator so that people could hear them coming...
Yup, just like people knew a long time ago. Observations like this were made at least ten years ago, if not 20 years ago.
Same goes for analysing the bumps on whale fins to study fluid flow.
It seems someone has run out of original ideas to secure research funding and has been dredging up old papers looking for "motivation".
"Yup, just like people knew a long time ago. Observations like this were made at least ten years ago, if not 20 years ago."
Yes! I recall having some "Anklebiter's Book of Science" maybe 30- 40 years ago, with a section called "Nature Beat Man to it" (or similar). It showed how the feathers on the trailing edge of owls' wings had gaps between them. The text explained that this broke up the airflow and reduced the noise. Similar methods were used on the arse-end of jet engines to make them quieter (paraphrasing a little).
Maybe there is something new here, possibly in the mention of the softer materials and porosity.
...because, generally speaking, they tend not to have a couple of Rolls Royce jet turbine engines strapped to their undercarriage.
ForthIsNotDead, don't be such a cynic! We only need to create owl wing shaped blades for the compressor and turbine and, hey presto, we have a silent jet engine. Too difficult? Alternatively, we try feeding owls into jet engines and see whether their feathers settle at the right place to create the desired outcome.
"We only need to create owl wing shaped blades for the compressor and turbine and, hey presto, we have a silent jet engine"
Silent apart from the turbulent exhaust flow that makes most of the noise. Maybe these scinetists could examine owl's bottoms, see if the cr@p comes out in a perfect laminar flow, and therefore offers the prospect of truly silent jet engines.
True! Maybe feeding owl into an owl-shaped blade jet engine would solve that problem as well? If we run out of owls I'd suggest ostriches - that would surely silence most jet engines.
"...because, generally speaking, they tend not to have a couple of Rolls Royce jet turbine engines strapped to their undercarriage."
A small detail that appears to have been overlooked.
Now putting a soft porus downy coating on the leading and trailing edges of the drive turbines.......
(I'm a big fan.)
You sound like a real blowhard to me.
Shit, they can't bloody well drive on the ground without smashing into each other.
Now, you want to see people in flying cars?!
I'm going to need an armoured rooftop!
That is a problem that owls don't have to contend with, so I don't see how they will help make submarines quiet. Unless there are owls I don't know about...
The Owls are not what they seem. Just ask Agent Cooper
(Very very old cult TV reference)
Cavitation only really happens when you're pushing the blades through the water faster than they're designed to go. There's still plenty of noise from propller blades without cavitation happening which this could possibly address assuming the greater density of water doesn't preclude the techniques being applicable.
You just need to hold the owl under water for long enough for it to stop fluttering around noisily, and then it is as whisper quiet in the water as it is in the air.
Extended pump jets.
The bubbles collapse inside of the jet body, the body permits destructive interference with the blade noise.
Then, from something that more beams noise in a restricted cone, one now has far, far, far less noise along that rearward facing cone.
Twin Peaks is possibly an old reference, but definitely not very old, and far far from very very old.
Now, the owls' three chief silent-flight attributes are: Tough leading feathers, soft trailing feathers, down at the top end, and an almost fanatical devotion to the pope. Hence the surprise.
"These crafty appurtenances let hunting owls plunge down out of the night sky in complete silence, the better to surprise their prey."
Plunging down silently out of the sky is the easy bit. It's been done many times before.
Remaining up in the sky silently is a lot more difficult.
Unless you're an owl.
"Plunging down silently out of the sky is the easy bit. It's been done many times before."
Well, you don't have to be silent, exactly...you just need to get there before the sound does...
It's not exactly silent during the plunge. There is all of that screaming going on...
Is the CIA working on an army of winged monkeys??
They already have them.
One is tempted to say something about Pakistan, but shall remain polite.
Who threw that?!
Does this mean an end to the sleep deprived nights caused by police choppers circling over my house?
Crisp, did you ever consider stop engaging in criminal activities so that police choppers won't have a need to circle over you place?
What I wondered though, several times while living nearby, what military choppers (ie WAH-64) were doing over the Isle of Dogs. Were/are you living there?
I used to get that too, when I lived in the UK. Always during the last 15 minutes of a good film too; I never knew how they knew. Always intended to get up on the roof to spell out 'fuck off' in Xmas lights; but never got around to it in the end.
I'm in the US and get much of that on a regular basis.
One good crash on the local superhighway, there are helicopters orbiting about filming the traffic snarl.
Then, to add insult to injury, there is a Boeing VERTOL plant about a mile away.
Of course, an upside to that is seeing the latest and greatest before anyone else does.
Well,stop growing stuff that you shouldn't in your attic.
Is that because they're high-drag? Does this mean that the quieting features are high-drag?
Flying cars don't really have the excess power if so.
"Does this mean that the quieting features are high-drag?"
No it means that a quieting feature is flying really slow. I'll wager that a seven tonne chopper doing 140 knots is never going to be in the slightest bit quiet, no matter how many owls are glued to its surface.
"......a seven tonne chopper doing 140 knots is never going to be in the slightest bit quiet...." Nothing to do with the speed of forward movement, chap, it's the speed the rotor blades are spinning at that matters. The wing of an owl gliding down onto pray is probably doing 30mph at most, whilst the tip of a helicopter's main rotor can be verging on supersonic. I doubt if a few fluffy feathers would make much difference if the owl's wing was slicing through the air at several hundred mph. The general rule with helicopters is the smaller the lifting surface area fan on top the faster you have to spin it just to stay up, let alone move forward. To lift a seven tonne chopper requires the fan shifting seven tonne plus of air downwards to generate the lift, which is an incomparable job with the "fixed" wing of a gliding owl. Lewis knows that, I'm surprised he didn't point it out.
Right? There is absolutely no comparison in the methods of flight between an owl an a helicopter. Though I suppose if you dropped a helicopter it would fall rather silently, like an owl does when it strikes, using that gravity stuff everybody keeps going on about. If a helicopter isn't making any rotor noise that's because it's stopped generating lift and you are about to fall.
It really makes you wonder if these scientists have ever seen an owl, or a helicopter...
And get it fitted to those really noisy egg-beaters called Chinooks that fly over my house evey frigging day going to RAF Odhiam? Please? PRetty Please.
They fly so frigging low that my whole house shakes.
You should have tried living on an operational Vulcan base!
Chopper noise - the Sound of Freedom...
The owlspinner portable.
Surely the excessive noise problem could be cured with the "Wonder"
substance, "Graphene"......on its way now......anytime soon......hmm....
"Graphene" must be stuck in a traffic jam somewhere.....anyway where
were we.....oh yes!...GLUE!...now what type of glue would you need to
stick an Owl on to a rotor blade.....maybe Apple could answer this?
You could be right - I'm hoping for lots of graphene tubes filled with hydrogen to act like dirigibles in the second world war to bring these things down.
Apple will try yet another prior art patent filing.
The question is, what would they use the theory for in practice? Not that this would stop them as history has proven.
The "human genome" was patented? News to me. I'm aware of *attempts* to patent *utilization* of *specific bits* of it in respect to *certain tests*, but I suppose that doesn't sound quite as dire.
Actually, it was specific genes that were patented.
The court found that such genes were a part of nature, hence cannot be patented.
They weren't designed genes, they were defective genes, such as with certain cancer cells and some genetic diseases.
Besides, everybody knows that scientists can't patent nature. Bill Gates beat them to it. :P
A Parliament of Owls are really quiet - Can't we get the same with our Parliament?
No they are not, there is all that hoo, who, hooting going on, although it would still be an improvement on our lot and most of the others I have seen/heard. My recommendation for a quiet parliament would be VX through the aircon system (well quiet after 5 minutes of coughing and gurgling) but I am afraid that's frowned upon for some reason that escapes me.
Black helicopter because I can hear someone abseiling down my chimney and it's way too early for Santa..arrgh!
PS: aren't owls quiet in flight so they can still hear their prey rustling through the leaves?
I wonder if these people have ever seen an owl in action? They are very quiet when they strike, because they are falling through the air. After they strike and when they're flying (i.e. their wings are moving) around owls aren't silent, at all. They make a great swooshing sound with every stroke.
Maybe it's because they are city scientists and they've never seen owls in the wild? I don't know. I do however know that if you go hang out at the silos on any farm that's got grain fed animals the rats will come at night (for the dropped grain) and you can watch the owls swoop down and take them away. You can sure as hell hear the owls then. I doubt they get quieter towards the city, background noise just gets louder...
isn't so much the energy use, the noise, or the physics of flight.
It's the idiocy of the general driving population.
An awful lot of people seem to have difficulty managing a vehicle on a flat surface in two dimensions. What makes anyone think that these mobile-using, non-indicating, lane-hogging, inconsiderate prats could ever handle three dimensions?
At the very least, I'm certain the aerial fatality rate to surface fatality rate would follow the square-cube law if we allowed the common idiot unfettered access to flying cars. The only way around it would be to have the vehicle under the control of an automated central guidance system at all times while off the ground. Which, given the increasing tendency of companies to want to take remote control of our computers, wouldn't be too much of a stretch for the public imagination.
Stupidity doesn't follow the square-cube law. It's logarithmic in nature.
If we end up with flying cars, I'll need an armoured roof and a rolled homogenous steel umbrella (from Acme).
"At the very least, I'm certain the aerial fatality rate to surface fatality rate would follow the square-cube law if we allowed the common idiot unfettered access to flying cars"
What about the Robinson R22 & R44 mini helicopters, often flogged to the stupid nouveau riche? Surely that's a good analogy for the relationship between road versus air accidents. As I recall, not many people actually killed, just lots and lots of minor take off and landing mishaps caused by pilot error and very few "falling out of the air on unlucky passer by" accidents.
Flying cars are like guns and chainsaws: In civilised countries simply wanting one is reason enough for disqualifying most applicants from owning one.
The R22 & R44 aren't mini helicopters. They are rather small, and yes some not quite wealthy people buy them in misguided attempts to show off, but they're the most popular commercial helicopter on the planet. The big fancy Sea Kings and stuff they show in the movies are extremely rare. Most short hop business flights, many police forces and news agencies choose the R44 because it's cheap and very reliable (for a helicopter).
Mini helicopters are an entirely different thing. Kind of like how ultralights and airplanes both use propellers and fixed wings, but aren't really comparable beyond that.
But I agree completely, the public shouldn't be allowed access to flying cars.
Accept my insincere apologies. I wasn't even aware that the term "mini helicopter" had any officially licensed application.
Yep. They're real. You just don't hear about them much because most are experimental and they're all insanely dangerous. The amount of complication in helicopter functionality just doesn't do 'medium' well. It's all simply too heavy for the amount of power available in the mini form factor.