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How do you estimate the ration of the torso of a bird to its wings? A bird in my world, the aquatic roc, is essentially a collasal pelican, big enough to scoop an average galleon, a ship of 160 feet. So that means the bird has to be at least 320 feet. How do I find the size of its wings?

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    $\begingroup$ This is not a remotely scientificaly plausable scenario. You need to use magic. In which case "fill your boots" you can do whatever you want. $\endgroup$
    – Slarty
    Nov 23, 2019 at 0:10
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    $\begingroup$ Please provide a link or further details of "the roc in dnd" I would be interested to investiagte this. $\endgroup$
    – Slarty
    Nov 23, 2019 at 0:18
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    $\begingroup$ Argentavis magnificens the largest bird ever that could fly .. Kori bustard the largest extant bird that can fly .. Quetzalcoatlus the largest flying animal ever, but when it flew the earth span a little faster so gravity was (ever so slightly) less, the atmosphere was thicker making larger flying animals easter & there was more oxygen allowing for more efficient flight muscles, so it might not be able to fly today .. 1/2 $\endgroup$
    – Pelinore
    Nov 23, 2019 at 0:29
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    $\begingroup$ Your basic problem is the square-cube law: as size increases, strength per unit of mass drops. 80-foot-long anything is going to be questionable. A wing even 40 feet long is impossible, at least in anything near a living bird. One problem: the force a wing that size creates by flapping would probably snap even an airplane wing in half, never mind bones and muscle. Also, with those huge wings come even bigger muscles to make them move, and at that scale you would likely need to be exceeding the speed of sound to stay aloft. There's other issues, too: that was just off the top of my head. $\endgroup$
    – Palarran
    Nov 23, 2019 at 0:30
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    $\begingroup$ If you use Quetzalcoatlus as a model for your giant pelican roc then its big enough to scoop up an average person but won't be able to scoop up even an ordinary rowboat of the sort that might seat 4 to 6 people .. 2/2 $\endgroup$
    – Pelinore
    Nov 23, 2019 at 0:35

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Kori bustard the largest extant bird that can fly.

Argentavis magnificens the largest bird ever that could fly.

Quetzalcoatlus the largest flying animal ever.

But when it flew, the Earth spun a little faster (so gravity was effectively (ever so slightly) less), the atmosphere was also thicker (making flying easter), & the atmosphere had a higher oxygen content (making muscles more efficient) ... so Quetzalcoatlus might not be able to fly today.

If you use Quetzalcoatlus as a model for your giant pelican roc, it is big enough to scoop up a normal person but won't be able to scoop up even an ordinary rowboat of the sort that seats 4 to 6 people.

In short, such a large bird is impossible in the real world, which means 'It's magic' is your only possible explanation for such a large bird. If that's what you're going with, then you can do whatever you want: slap a pair of normal size hummingbird wings on it if you want, & you're good to go.

Howsoever.

If you just want scale up an ordinary pelican & what you're asking for is their dimensions, then you want a wingspan of perhaps a bit more than 150% of its body length.

A normal Pelican is "Length 1.3–1.8 m (4.3–5.9 ft), wingspan 2.44–2.9 m (8.0–9.5 ft)"

You talk about it scooping up a galleon, presumably this is in it's beak the way a pelican catches fish?

In which case it's perhaps worth noting that the beak is maybe only a third of the bird’s body length.

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