Scientists at Stanford University in the US have developed a super-sensitive device that can measure the weight of a bird in flight.
The invention, created by Prof David Lentink’s research team, measures the force produced by every wing flap.
The device, described in the Royal Society journal Interface, will enable researchers to carry out tests of miniature drones, to assess more precisely their flight performance.
It has also answered a physics riddle.
This question, Prof Lentink explained, is whether a container or a truck carrying birds changes in weight when the birds inside were flying.
It was investigated in an episode of the US television show MythBusters; the presenters weighed a trailer while birds flew inside it, and concluded that it was no different to when the birds were still.
This new device, however, is so precise, that it shows that this is not quite right; the weight of the container would actually change as the birds flapped their wings.
The Stanford team explained that measurements taken from a single bird showed that hovering created “double the lift during the downstroke [of the wings] so that the birds did not have to lift their weight during the upstroke”.
.Researchers developed a special enclosure to measure the tiny forces from every beat of a bird’s wings
“So, the weight of a truck containing just a few flying birds will fluctuate in time; only the lift of an incoherent flock of birds could cancel out [this change],” Prof Lentink summarised.
He and his colleagues tested their new device by recording the tiny forces from a single bird flying inside the specially designed chamber.
Question is, do I still bang on the sides of a box ?
Birds can only hover in a moving air stream, where’s the moving air stream in a box?
Likewise, if birds are flying inside a box, surely the downbeat of their wings would affect the pressure,(weight), on the floor of the box equal to the weight of the bird.?
bestbooties:
Birds can only hover in a moving air stream, where’s the moving air stream in a box?
Likewise, if birds are flying inside a box, surely the downbeat of their wings would affect the pressure,(weight), on the floor of the box equal to the weight of the bird.?
As far as I know, a bird in a box on the floor or in flight has the same overall mass - One of these daft physics questions where you’re never ever going to get a “bird in flight” inside any container whatsoever of course.
If the gross mass were to change - then you could jump up in the air halfway down a train corridor - and bang into the back wall.
This entire concept belongs with the "Do you walk, or are you pushing the world around like a roller under your feet" type funnyfarm arguments…
Other such questions include: “If a tree falls down in the forest, and there’s no one there to hear it - does it make a sound?”
“Can you lift yourself up off the ground into mid-air if you’re strong enough?”
“If superman catches lois lane falling off a skyscraper - does she go “SPLAT” into his arms at terminal velocity?”
and not forgetting the El Capitan nonsense from Star Trek as well…
What Kirk is doing has just been done in real life of course… It’s Spock’s hover boots that are absurd…
Congratulations to Tommy Caldwell and Kevin Jorgeson to their feat that’ll make them the envy of steeplejacks around the world…
plus where these birds carrying coconuts …and from the southern hemisphere it does make a difference …and some of the birds haven’t moved since they was nailed on the perch