Seconded.
More precisely, sectional density (mass per cross-sectional area), not full density (mass per volume). A chicken definitely has less sectional density than a vertical human, but might have more than a horizontal human.
And even domesticated chickens can fly. I’ve seen them do it. They’re not very good at it, but we’re not looking for soaring here, just falling with style. Or without style, but at least survivably.
Zactly. Style points are strictly optional.
Assuming I’m the “they” you’re referring to, I may have been a bit sloppy. For a given shape, if you specify size and weight, then the density is fixed. If you specified density and size, then weight is fixed. The chicken weighs a lot less than the skydiver, largely because it’s just smaller. It’s probably true that it is also less dense, but I also wonder about the effective density of a skydiver who is wearing a loose fitting skydiving suit and helmet.
I have a free-fall calculator spreadsheet that can maybe help answer some of these questions, but I won’t have access to it for another couple of weeks. But for any given object, if you can come up with a drag coefficient, density, and size, I can estimate how long it will take to fall a given distance, and what its terminal velocity would be.
Haldane’s “On Being the Right Size” has a good summary of this issue
"You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom, it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes. For the resistance presented to movement by the air is proportional to the surface of the moving object. Divide an animal’s length, breadth, and height each by ten; its weight is reduced to a thousandth, but its surface only to a hundredth. "
Also known as the square-cube law.
Another point is shape. Since the rise in fuel prices since 1970, large trucks have begun using those shaped spoilers on the roof. I read once that even just rounding the corners on a cube like a tractor-trailer makes a significant difference on its wind resistance (drag). Spherical chickens have less drag than cubic ones, hence a higher terminal velocity.
Also, the location of center of gravity will determine the orientationin during fall.
You mean a comment about a bag of wet cement?
I dug up my ballistics calculator and did a few runs. The cannonball beats the grape handily.
For an iron (7874 kg/m^3) cannonball 0.141 meters diameter dropped from a height of 600 m, it’ll hit ground after 11.5 seconds, with an impact velocity of 97.2 m/s (217 MPH). Dropped from a much higher altitude (and disregarding any changes in atmospheric density due to altitude), its terminal velocity would be about 160 m/s (358 MPH).
For a grape (1000 kg/m^3) 0.025 meters in diameter dropped from a height of 600 m, it’ll hit ground after 26.4 seconds, with an impact velocity of 24.3 m/s (54.4 MPH). This is in fact its terminal velocity, achieved after about ten seconds of freefall.
For an avian projectile, we’d need decent estimates of density and size. Assume a 41-pound (18.6-kg) turkey that’s roughly-sphere shaped. The overall density would have to be something less than that of water (muscle tissue is about the same as water, but fat is considerably less dense, and feathers would reduce the effective density even more; there’s also the lungs and air sacs). I’ll assume an overall density of 700 kg/m^3, or 70% that of water. A sphere 0.37 m in diameter gives a mass of 18.6 kg. For a drop of 600 m, it’ll hit ground after 12.9 seconds at a velocity of 71.8 m/s (161 MPH). Terminal velocity when dropped from much higher is 77.5 m/s, or 173 MPH.
For the 17-lb (7.7-kg) hen:
- 0.276-m sphere
- 600-m drop lasts 13.6 seconds with an impact velocity of 64.5 m/s (144 MPH)
- 66.9 m/s (150 MPH) terminal velocity from much higher
The above-described turkey is simplified to make the math easier. I don’t know how realistic my density estimate is, and a real turkey, as described upthread, would likely be flapping and flopping on the way down, creating more drag and reducing its velocity. FWIW, Google’s AI overview says the overall density of a duck is 520 kg/m^3; it doesn’t give a good answer for a whole live turkey (just turkey meat), but if 520 is a reasonable density for a duck (which is evolved to float and fly), then 700 is probably a reasonable density for a whole live turkey.
I don’t think the huge domestic turkeys bred for food can fly at all as adults. Some of them get so fat they can’t walk.