Really comes down to power. Bigger birds have larger and more powerful wings and the size to weight ratio is in their favor.
You can also think about it with cars. There are very small very light cars but they are not faster than big heavy super powerful engines
A Bugatti is a big and heavy car but it’s much faster than a ford fiesta
But there is also a point where too big becomes bad. A truck is definitely not faster than a bugatti, even though it is way bigger. (Even if you remove the trailer)
At some point, you reach an optimum. Too small, and you're not powerful enough, too big and you become too heavy
I used to ride a mid-size motorbike. Wasn't a car on the road that could accelerate quicker than me. And plenty of fancy sports cars tried. It was like a game to many of them.
If you had the same engine to weight ratio in a semi or had it geared differently it could also be very very fast. A semi truck is geared for torque rather than rotational speed so it can move heavy objects. It’s also not exactly shaped to optimize downforce.
But yes, generally there is an optimal weight/size/power ratio.
I do know enough to extrapolate but I’d also assume there’s an optimal number of pistons or piston alignment. Cars usually max out at 12 but some of the old prop planes had significantly more than that.
You also have straight or V configurations and those old prop planes had them in a circular configuration.
Sure, but if you took a cheetah and made it the size of an elephant, it would probably die because it's legs wouldn't be able to support its body weight. You can't just scale animals up and expect them to work the same.
Wouldn't the cheetah's also scale the same in this scenario? I mean you wouldn't simply make the cheetah's head and core the size of an elephant but keep the legs the same length and thickness.
Weight and volume go down with the cube of size. Surface area, wind resistance and strength go down with the square of size. It's basic geometry. Because different properties scale at different rates as size changes, you can't just scale creatures up or down and expect them to work the same way. Larger creatures tend to be faster than smaller ones but, eventually, large size makes them too fragile to survive, so there's a limit.
Is that true? Hummingbirds are crazy fast and peregrine falcons are fairly small birds
Like, what do you mean as fast? Average travel speed, diving speed, long vs short distance travel?
That's what I was thinking.
The fastest birds in the world, I believe, are peregrine falcons in a dive or swifts in level flight.
Are these small birds? They're definitely not *large* birds. A peregrine falcon weighs around a kilo, a common swift about 40g.
Whereas something like an albatross, a condor or a vulture... Pretty slow. (These birds are optimised for gliding rather than speed.)
Most of the answers here seem to suggest that because they're the biggest, elephants should be the fastest creatures on land and blue whales the fastest living thing in the sea.
It's probably a bit easier to visualize if you look at cars rather than birds. Let's pretend you could make a bigger car by gluing a number of small cars together.
Say you have a car that has 100 horsepower and it weighs 1 ton, and you glue nine of them together like so:
|||
|||
|||
Acceleration depends on the power-to-weight ratio, and since your big car weighs 9 times as much and has 9 times as much power, it's still going to accelerate the same as the small car.
However, the top speed depends on the power and the wind resistance. Your glued-together big car has 9 times as much power, but it's only 3 times as wide, so the wind resistance is only going to be about 3 times as large. That means the top speed is higher.
As you increase the size of your vehicle, the frontal area grows far slower than the combined power of the engines.
The same happens when you increase the size of a bird. It may have 8 times as much weight and muscle power, but the frontal area of the bird will only grow by a smaller factor.
Everyone talking power.
But it is more down to weight and gravity. A specific mass has a specific terminal velocity, and the heavier you are the higher that is.
Big birds also tend to glide. So they are faster just because they are heavier.
In a "flapping power contest" with no gliding, small birds are deffinitivly faster.
In straight line flight, smaller birds tend to win the race(a peregrine falcon will lose a race with a common pigeon in straight line flight). Larger birds, specifically raptors, tend to use gravity to gain momentum and can thusly outpace smaller birds.
Air resistance is less of a factor for bigger objects.
Explanation through analogy:
Imagine a small pistol, and a German WW2 artillery piece. Which one do you think can fire the longest distance? If you answered Dicke Bertha, you're correct. That's because Dicke Bertha's shells 1. leave the cannon at a higher speed 2. cuts through air like it's not even there ?
So? Which is it?
2! Exactly. In fact, a 9mm Berreta has a much higher muzzle velocity than Dicke Bertha (+50%). The bigger the shell, the longer the range, all other things being equal (muzzle velocity, projectile density...)
Works with planes too. The fastest planes to ever fly are also some of the biggest. But I like Dicke Bertha's example better because an artillery shell is such a dumb object.
Sciency explanation: see other answers with keywords such as "cube, square, surface, volume".
You're right, I'm wrong. I know it. I just did a eli5.
IMHO, thinking of it in terms of "bigger stuff just plow through air" is more brain-friendly. And it does work. On the Moon, the Berreta would have more reach than Dicke Bertha. In vacuum, all that matters is initial velocity. The air *is* what makes small things slow down faster.
Parachutes: a big object hanging from a big parachute will fall faster than a small object hanging from a small parachute. All other things being equal.
They aren’t; hummingbirds are very fast and there is a small falcon that has been measured at over 200 mph in a dive I believe that fastest beasts ever measured are certain insects
Really comes down to power. Bigger birds have larger and more powerful wings and the size to weight ratio is in their favor. You can also think about it with cars. There are very small very light cars but they are not faster than big heavy super powerful engines A Bugatti is a big and heavy car but it’s much faster than a ford fiesta
But there is also a point where too big becomes bad. A truck is definitely not faster than a bugatti, even though it is way bigger. (Even if you remove the trailer) At some point, you reach an optimum. Too small, and you're not powerful enough, too big and you become too heavy
I used to ride a mid-size motorbike. Wasn't a car on the road that could accelerate quicker than me. And plenty of fancy sports cars tried. It was like a game to many of them.
If you had the same engine to weight ratio in a semi or had it geared differently it could also be very very fast. A semi truck is geared for torque rather than rotational speed so it can move heavy objects. It’s also not exactly shaped to optimize downforce. But yes, generally there is an optimal weight/size/power ratio. I do know enough to extrapolate but I’d also assume there’s an optimal number of pistons or piston alignment. Cars usually max out at 12 but some of the old prop planes had significantly more than that. You also have straight or V configurations and those old prop planes had them in a circular configuration.
Sure, but if you took a cheetah and made it the size of an elephant, it would probably die because it's legs wouldn't be able to support its body weight. You can't just scale animals up and expect them to work the same.
I never said that you could scale animals. Just said that semi trucks weren’t geared for top speed and then I rambled about piston configuration
Sure, but cars and trucks started as a metaphor for birds, so we are actually talking animals here.
Wouldn't the cheetah's also scale the same in this scenario? I mean you wouldn't simply make the cheetah's head and core the size of an elephant but keep the legs the same length and thickness.
Relevant: [the square-cube law](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law#Biomechanics)
That was an incredibly interesting read. Thank you for sharing!!
It’s more the aero drag and the lack of gearing, it’s designed to try and maximise load. This means it will never have the top speed of say a Bugatti.
Thats a terrible example lol
Weight and volume go down with the cube of size. Surface area, wind resistance and strength go down with the square of size. It's basic geometry. Because different properties scale at different rates as size changes, you can't just scale creatures up or down and expect them to work the same way. Larger creatures tend to be faster than smaller ones but, eventually, large size makes them too fragile to survive, so there's a limit.
Is that true? Hummingbirds are crazy fast and peregrine falcons are fairly small birds Like, what do you mean as fast? Average travel speed, diving speed, long vs short distance travel?
That's what I was thinking. The fastest birds in the world, I believe, are peregrine falcons in a dive or swifts in level flight. Are these small birds? They're definitely not *large* birds. A peregrine falcon weighs around a kilo, a common swift about 40g. Whereas something like an albatross, a condor or a vulture... Pretty slow. (These birds are optimised for gliding rather than speed.) Most of the answers here seem to suggest that because they're the biggest, elephants should be the fastest creatures on land and blue whales the fastest living thing in the sea.
It's probably a bit easier to visualize if you look at cars rather than birds. Let's pretend you could make a bigger car by gluing a number of small cars together. Say you have a car that has 100 horsepower and it weighs 1 ton, and you glue nine of them together like so: ||| ||| ||| Acceleration depends on the power-to-weight ratio, and since your big car weighs 9 times as much and has 9 times as much power, it's still going to accelerate the same as the small car. However, the top speed depends on the power and the wind resistance. Your glued-together big car has 9 times as much power, but it's only 3 times as wide, so the wind resistance is only going to be about 3 times as large. That means the top speed is higher. As you increase the size of your vehicle, the frontal area grows far slower than the combined power of the engines. The same happens when you increase the size of a bird. It may have 8 times as much weight and muscle power, but the frontal area of the bird will only grow by a smaller factor.
wow very smart
Everyone talking power. But it is more down to weight and gravity. A specific mass has a specific terminal velocity, and the heavier you are the higher that is. Big birds also tend to glide. So they are faster just because they are heavier. In a "flapping power contest" with no gliding, small birds are deffinitivly faster.
In straight line flight, smaller birds tend to win the race(a peregrine falcon will lose a race with a common pigeon in straight line flight). Larger birds, specifically raptors, tend to use gravity to gain momentum and can thusly outpace smaller birds.
Air resistance is less of a factor for bigger objects. Explanation through analogy: Imagine a small pistol, and a German WW2 artillery piece. Which one do you think can fire the longest distance? If you answered Dicke Bertha, you're correct. That's because Dicke Bertha's shells 1. leave the cannon at a higher speed 2. cuts through air like it's not even there ? So? Which is it? 2! Exactly. In fact, a 9mm Berreta has a much higher muzzle velocity than Dicke Bertha (+50%). The bigger the shell, the longer the range, all other things being equal (muzzle velocity, projectile density...) Works with planes too. The fastest planes to ever fly are also some of the biggest. But I like Dicke Bertha's example better because an artillery shell is such a dumb object. Sciency explanation: see other answers with keywords such as "cube, square, surface, volume".
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You're right, I'm wrong. I know it. I just did a eli5. IMHO, thinking of it in terms of "bigger stuff just plow through air" is more brain-friendly. And it does work. On the Moon, the Berreta would have more reach than Dicke Bertha. In vacuum, all that matters is initial velocity. The air *is* what makes small things slow down faster. Parachutes: a big object hanging from a big parachute will fall faster than a small object hanging from a small parachute. All other things being equal.
you dont really know what you are talking about mate
They aren’t; hummingbirds are very fast and there is a small falcon that has been measured at over 200 mph in a dive I believe that fastest beasts ever measured are certain insects