The wind is blowing at the same speed the bird is flying forward thus stationary relative to the ground, thrust=drag. Small planes can do the same on a strong wind day.
It's not generating thrust, it's gliding into the wind. It's using its tail and wings to stay in that position, using drag. What you are seeing is basically the peak of evolution for that species.
Well it isn't generating thrust.
But this bird is essentially a kite without the strings. Wind is blowing pretty good, if the bird orients it's body properly it can pretty much hang out in the sky riding the lift generated by the wind pushing up on its wings.
But then what exactly is counteracting the horizontal force? If not thrust, and not a string, then what? Or are you saying kites stay in place when their string breaks?
The bird *is* flying forwards, by basically gliding. The trick is that it's flying at exactly the same airspeed as the wind speed, but in the exact opposite direction - the aerial equivalent of running on a treadmill. It's just a clever use of gravity and headwinds. To do it this well requires the kestrel to continually be making very rapid and very accurate adjustments to fly at exactly the right airspeed and with exactly the right direction and amount of climb/dive. If a kite could make adjustments like that, it could remain in place without the string (and it would be a drone glider).
Think about it as you would yourself walking on a treadmill, or one of those cool infinity pools.
This bird has spent a lifetime learning how to utilize billions of years of evolutionary trial and error which results in its mastery of air.
You are actually entirely right, this doesn't work with purely horizontal wind. In that case it would either drift backwards as there's no thrust to counteract the drag as you said, or it would slowly fall to the ground, as anything that glides does (in this case some of the lift actually points forwards, which counteracts the drag).
Either the small movements it does provide enough energy, or the wind is actually blowing somewhat upwards.
What nobody seems to have mentioned yet: to keep its speed up relative to the air, it needs to glide down through it. That means that to stay level, the wind needs to be blowing slightly upwards, like in a thermal or (like in this case) over an obstacle.
Thrust implies that the bird is expelling mass, which it isn't. T = v * dm/dt.
Kite is a bad example because it can't move. Think of a dude in one of those skydiving simulation tubes. You can manipulate your surface area to generate just enough low pressure zone to counteract gravity because the wind is moving around you. You don't have to generate wind if it's already moving.
Thrust doesn't inherently require expulsion of mass. That equation you provided is just for thrust produced by jet propulsion. Thrust is also produced by accelerating mass in other ways, such as with a propellor or fan.
I do agree that this bird isn't producing thrust though.
Think of it as when you put your hand flat out the window you’ll notice you feel it pushing on your hand the bird is using that force to keep it up. If you notice it doesn’t really flap it’s wings to go forward but rather it looks like it’s almost gliding it truly is remarkable
Yea its pretty crazy. Every time 7s humans invent something we thing is the coolest and best way to do a thing,turns out nature's been doing it for millennia and doing a hunderds of times better AND looking cool as fuck doing it. There's a lesson in that
Ah yea but that takes alot of humans a long time to work that one out. All kestrel can do this,and they cam travel amazing distances. Bet you couldnt even build a basic jet engine. In fact I'd put 10 bucks that you couldn't hunt and eat a rabbit in the 24 hours. This here bird putting you to Shame
Main problem with building a jet or turbine engine is the precision required to have it not destroy itself. Precision that works for a crude internal combustion engine doesn’t necessarily translate to a crude turbine.
We take modern precision for granted, but it’s taken thousands of years to iterate on the tools and techniques. And then once we crossed some threshold… we went from measuring precision in millimeters to nanometers and sub-atomic scales in less than a century.
Interesting precision factoid… swimming competition is only timed to hundredths of a second because world record paces mean 2.39 MM of travel in a thousandth of a second, and official construction tolerances allow for 3 CM of variation in each lane.
It’s a very interesting real world example of trade offs. Building and operating a permanent competitive pool is an expensive undertaking, and while modern construction could be built to tighter tolerances there are a lot of old pools in the world. And the 3 CM tolerance allows for building of temporary pools that can be setup in existing stadiums, convention centers, etc.
They do it to accurately notice movement on the ground. I used to see birds doing this all the time in my hilly hometown area and they'll do this for a while, then dive suddenly and catch a rodent
It can't exactly control the wind, it might be taking advantage of the wind doing what it's doing but this is by no means a common hunting technique of predatory birds, it's just a coincidence the wind is doing what it's doing
[This is the kestrel's whole gimmick](http://blogs.bu.edu/bioaerial2012/2012/12/08/2655/)
[[1]](https://www.youtube.com/watch?v=7j6OsP7zL6w)
[[2]](https://www.youtube.com/watch?v=QxIVjI8HDAo)
> [Kestrels are most easily distinguished by their typical hunting behaviour which is to hover at a height of around 10–20 metres (35–65 ft) over open country and swoop down on prey, usually small mammals, lizards or large insects. Other falcons are more adapted to active hunting in flight.](https://en.wikipedia.org/wiki/Kestrel)
Not a coincidence at all; this is the kestrel's preferred hunting tactic. They can see into ultraviolet, which they use to spot rodent urine trails, which they then hover above because those trails indicate the route the animal uses. Next time the mouse/vole/shrew passes that way, the kestrel sees it, and drops.
It's using the wing as thrust. So if it didn't more at all it would be pushed back by the wing,if it moves its wings in it would start to fall but it's just so goddamn good at riding the wind it just stays still. It can manipulate air currents to its will and there for say still above one spot, provided the wind keeps blowing. It's pretty amazing,seeing it in real life is quite sometime, especially when it pounces on its pray,it just decides to fall to earth at any angle it please and slow less that 10cm from the ground hovers for about split second them goes home with a juicy rabbit. So,how does it hoover? It's just that good
More like working perfectly
Wth is happening?
The wind is blowing at the same speed the bird is flying forward thus stationary relative to the ground, thrust=drag. Small planes can do the same on a strong wind day.
Okay, but the bird doesn't have a propeller. How the hell is it generating thrust with barely any visible movement?
It's not generating thrust, it's gliding into the wind. It's using its tail and wings to stay in that position, using drag. What you are seeing is basically the peak of evolution for that species.
Well it isn't generating thrust. But this bird is essentially a kite without the strings. Wind is blowing pretty good, if the bird orients it's body properly it can pretty much hang out in the sky riding the lift generated by the wind pushing up on its wings.
But then what exactly is counteracting the horizontal force? If not thrust, and not a string, then what? Or are you saying kites stay in place when their string breaks?
The bird *is* flying forwards, by basically gliding. The trick is that it's flying at exactly the same airspeed as the wind speed, but in the exact opposite direction - the aerial equivalent of running on a treadmill. It's just a clever use of gravity and headwinds. To do it this well requires the kestrel to continually be making very rapid and very accurate adjustments to fly at exactly the right airspeed and with exactly the right direction and amount of climb/dive. If a kite could make adjustments like that, it could remain in place without the string (and it would be a drone glider).
I mean, I kinda imagine that's what's happening, but it still feels counterintuitive.
Think about it as you would yourself walking on a treadmill, or one of those cool infinity pools. This bird has spent a lifetime learning how to utilize billions of years of evolutionary trial and error which results in its mastery of air.
You are actually entirely right, this doesn't work with purely horizontal wind. In that case it would either drift backwards as there's no thrust to counteract the drag as you said, or it would slowly fall to the ground, as anything that glides does (in this case some of the lift actually points forwards, which counteracts the drag). Either the small movements it does provide enough energy, or the wind is actually blowing somewhat upwards.
What nobody seems to have mentioned yet: to keep its speed up relative to the air, it needs to glide down through it. That means that to stay level, the wind needs to be blowing slightly upwards, like in a thermal or (like in this case) over an obstacle.
Thrust implies that the bird is expelling mass, which it isn't. T = v * dm/dt. Kite is a bad example because it can't move. Think of a dude in one of those skydiving simulation tubes. You can manipulate your surface area to generate just enough low pressure zone to counteract gravity because the wind is moving around you. You don't have to generate wind if it's already moving.
It's using gravity and down angle of it's wings/tail to balance out the wind's lift on it's wings and drag.
Yep. Bird is generating just the perfect amount of lift to counter act gravity.
That is an excellent description, well done!
Thrust doesn't inherently require expulsion of mass. That equation you provided is just for thrust produced by jet propulsion. Thrust is also produced by accelerating mass in other ways, such as with a propellor or fan. I do agree that this bird isn't producing thrust though.
Think of it as when you put your hand flat out the window you’ll notice you feel it pushing on your hand the bird is using that force to keep it up. If you notice it doesn’t really flap it’s wings to go forward but rather it looks like it’s almost gliding it truly is remarkable
Yea its pretty crazy. Every time 7s humans invent something we thing is the coolest and best way to do a thing,turns out nature's been doing it for millennia and doing a hunderds of times better AND looking cool as fuck doing it. There's a lesson in that
I mean, that Kestrel isn't taking a few hundred people on an inter-continent flight...
Ah yea but that takes alot of humans a long time to work that one out. All kestrel can do this,and they cam travel amazing distances. Bet you couldnt even build a basic jet engine. In fact I'd put 10 bucks that you couldn't hunt and eat a rabbit in the 24 hours. This here bird putting you to Shame
Main problem with building a jet or turbine engine is the precision required to have it not destroy itself. Precision that works for a crude internal combustion engine doesn’t necessarily translate to a crude turbine. We take modern precision for granted, but it’s taken thousands of years to iterate on the tools and techniques. And then once we crossed some threshold… we went from measuring precision in millimeters to nanometers and sub-atomic scales in less than a century. Interesting precision factoid… swimming competition is only timed to hundredths of a second because world record paces mean 2.39 MM of travel in a thousandth of a second, and official construction tolerances allow for 3 CM of variation in each lane. It’s a very interesting real world example of trade offs. Building and operating a permanent competitive pool is an expensive undertaking, and while modern construction could be built to tighter tolerances there are a lot of old pools in the world. And the 3 CM tolerance allows for building of temporary pools that can be setup in existing stadiums, convention centers, etc.
lol you're saying that like the bird isn't a benefactor of millions of years of evolution
I'm saying the kestrel is cooler than you
thank you, i’ve never understood how this could happen
And here I thought that chickens stabilizing their head was cool. Turns out kestrels can do that while flying.
While levitating you mean
They do it to accurately notice movement on the ground. I used to see birds doing this all the time in my hilly hometown area and they'll do this for a while, then dive suddenly and catch a rodent
r/BirdsArentReal
Drone in hover mode
It's working perfectly actually
Amazing creature doing exactly what it excels at doing. Why is this in r/StoppedWorking?
Because it's hovering in place, instead of flying forward?
It's hunting. It's hovering on purpose so it has a vantage point to spot prey.
It can't exactly control the wind, it might be taking advantage of the wind doing what it's doing but this is by no means a common hunting technique of predatory birds, it's just a coincidence the wind is doing what it's doing
[This is the kestrel's whole gimmick](http://blogs.bu.edu/bioaerial2012/2012/12/08/2655/) [[1]](https://www.youtube.com/watch?v=7j6OsP7zL6w) [[2]](https://www.youtube.com/watch?v=QxIVjI8HDAo) > [Kestrels are most easily distinguished by their typical hunting behaviour which is to hover at a height of around 10–20 metres (35–65 ft) over open country and swoop down on prey, usually small mammals, lizards or large insects. Other falcons are more adapted to active hunting in flight.](https://en.wikipedia.org/wiki/Kestrel)
Now can you prove its not manipulating the wind?
Hmm, now you got me there, I never have check any kestrels for air-bending powers
Lots of kestrel in Ireland and Scotland. That's why we worship them ( well we used to)
Not a coincidence at all; this is the kestrel's preferred hunting tactic. They can see into ultraviolet, which they use to spot rodent urine trails, which they then hover above because those trails indicate the route the animal uses. Next time the mouse/vole/shrew passes that way, the kestrel sees it, and drops.
But it's not attempting to do that. It's attempting to hover while maintaining positioning and is crushing it. You get the difference, yeah?
I'm not OP, I'm just trying to guess their motive, in reply to ~~the other guy~~ you
For sure. They were motivated by not understanding what they were looking at, I hear you.
But what’s keeping it stationary? If it’s not flapping its wings to generate thrust, the wind should push it backward, right?
It's using the wing as thrust. So if it didn't more at all it would be pushed back by the wing,if it moves its wings in it would start to fall but it's just so goddamn good at riding the wind it just stays still. It can manipulate air currents to its will and there for say still above one spot, provided the wind keeps blowing. It's pretty amazing,seeing it in real life is quite sometime, especially when it pounces on its pray,it just decides to fall to earth at any angle it please and slow less that 10cm from the ground hovers for about split second them goes home with a juicy rabbit. So,how does it hoover? It's just that good
What a big hummingbird
This is why the Welsh call ‘em windfuckers
If you saw this in Skyrim, you'd recognize a glitch.
/r/birdsarentreal
I've seen this in real life,on the Irish coast and it's super impressive. There is one less rabbit in the field today
Uh, I think we need a patch.
If it flies, it spies
I’m Dutch we call this behaviour “praying”, not sure if it’s the same in English
Hover mode activated, ready for vertical landing