D&D General Are dragons wings too small/little?

[Umbran]

The blimp issue can be easily solved by distributing dragon gas exchange throughout its body in a series of distinct ‘air sacs’ rather than a single cavity.

With respect, go look at a hot air balloon for a minute. One that's designed to lift a few people in a basket.

Look at the volume of the balloon.

Exactly how big is your dragon, again? In air, the volume that you need to lift a body by displacement is much, much larger than typical animal bodies - to lift a few hundred pounds of mass by air displacement, you need a volume like a hot air balloon! The dragon weighs several times that.

 

[TheCosmicKid]

This is where being a fantasy creature comes in. I am not sure most of the time that you want them to be 1000 times the physical size, but only 100 times the weight. In our case, 100 times the weight of the eagle is only 3000 pounds - on the order of the weight of a large bull. Aside from blowing away in the wind... it would mean that any predator who could take down a large bull might also have a chance at the dragon.

So, no, let us not reduce the weight. Instead, increase how much you get for that weight. In normal animals, as you say, the force muscles can exert is proportional to the cross sectional area of the muscle fiber bundle - if I am 10 times the size in each dimension, I am 1000 times the weight, but only 100 times as strong. Whoops!

Fix that one thing - muscle power, and it all works. The muscles of our large fantasy creatures are incredibly powerful as compared to our smaller fantasy creatures. Giants, Dragons, and so on, have some force multiplier. Their connective tissues and bone strength (not overall weight, just their strength) must increase to take the larger loads. But then, you're done.

So, really powerful muscle, and dragon and giant bones that are stronger than metals. And that's cool anyway.

I think there's a place to meet in the middle here. I'm fine with saying that dragons are lighter than you might expect for a creature of their size: they're titanium and carbon fiber as opposed to the steel of something like a giant. But no, blowing away in the wind would be rather undignified.

 

[Umbran]

What is your point exactly?

That "supernaturally lighter" is not significantly different from "floating like a blimp".

Go watch footage of people walking on the Moon. That's the motion of people who are supernaturally lighter than you'd expect. They bob along kind of like balloons.

 

[Dausuul]

That "supernaturally lighter" is not significantly different from "floating like a blimp".

Yes, it is. A dragon that is light but heavier than air still behaves like the flying animals we know. It soars and banks and dives. If you bind its wings, it falls. A blimp does none of this. It just floats.

Go watch footage of people walking on the Moon. That's the motion of people who are supernaturally lighter than you'd expect. They bob along kind of like balloons.

Go read Galileo. Heavy objects and light ones fall at the same speed in the same gravitational field. The Moon has a different gravitational field. The weight of the astronaut has nothing to do with it.

 

[Tonguez]

With respect, go look at a hot air balloon for a minute. One that's designed to lift a few people in a basket.

Look at the volume of the balloon.

Exactly how big is your dragon, again? In air, the volume that you need to lift a body by displacement is much, much larger than typical animal bodies - to lift a few hundred pounds of mass by air displacement, you need a volume like a hot air balloon! The dragon weighs several times that.

One thing I did notice when looking at Medieval depictions of Dragons that they tended to be smaller than the modern view and also they tended to have serpentine neck and tails on round bodies - exactly as would be expected of a "blimp serpent" so maybe the serpentine depiction of dragona is more accurate, giving them reletively light weight but due to their ability to 'blimp up' legends have claimed they are much much larger than we have come to expect

Of course they also tend to be bipedal which might make them wyverns rather than dragons

 

[TheCosmicKid]

Yes, it is. A dragon that is light but heavier than air still behaves like the flying animals we know. It soars and banks and dives. If you bind its wings, it falls. A blimp does none of this. It just floats.

Eh, it depends how much heavier than air. Feathers are heavier than air, but they still float around a lot.

 

[dave2008]

I think there's a place to meet in the middle here. I'm fine with saying that dragons are lighter than you might expect for a creature of their size: they're titanium and carbon fiber as opposed to the steel of something like a giant. But no, blowing away in the wind would be rather undignified.

True, but for my fantasy I would rather dragons trend to the stronger strength of materials side than the air-filled blimp side. i would expect their design would incorporate strategies to make them as light as possible (i.e. diamond fiber is extremely hard and strong, but light as well), but personally I want my dragons to look like dragons first and realistically fly second.

 

[Dausuul]

Eh, it depends how much heavier than air. Feathers are heavier than air, but they still float around a lot.

Well, yes, but I'm not proposing reducing the dragon's density to the point where it would drift like a feather. A creature the size of a dragon, at 20% the density of normal flesh, would still fall quite fast if its wings were folded.

What I am trying to do is get to a creature that flies in the same manner as a large bird--the way most of us expect a dragon to fly, soaring majestically before it folds its wings and dives to spew fire. Umbran's solution of "just make it stronger" is a problem because no matter how strong the dragon is, the surface area of its wings determines how much lift it can generate per flap; Hercules cannot fly by flapping his arms. As you pointed out earlier, a dragon relying purely on stronger wings would have to fly like a colossal hummingbird, beating its wings at blurring speeds, and it would have to do this all the time. It could not soar or glide. As soon as its wings stopped moving or even slowed down, it would plummet.

Alternatively, the dragon could use its strength to make its wings bigger. But this leads to a dragon with a 40-foot body and 1,000-foot wingspan.

The blimp-dragon is the end result of "just make it lighter." Again, though, such a dragon's flight would look very different from what we expect. It would not so much fly as swim through the air. When at rest, it would simply drift above the ground. That fits nicely with Eastern-style dragons, which are generally portrayed without any wings at all. But for Western-style dragons, it would look utterly bizarre.

So, the middle ground is a place where we make the dragon strong enough to support a reasonably larger wing surface, and light enough for those wings to lift it in a birdlike way, without making its wings absurdly outsized and without making it so light that it cannot fall.

 

[TheCosmicKid]

So, the middle ground is a place where we make the dragon strong enough to support a reasonably larger wing surface, and light enough for those wings to lift it in a birdlike way, without making its wings absurdly outsized and without making it so light that it cannot fall.

I think we're pretty much on the same page here.

For the largest dragons, I suspect if you sat down and ran the numbers (which I have not) you might still need to do some fudging to avoid the hummingbird-or-feather problem, but anything south of Quetzalcoatlus in dimensions is clearly at least within spitting distance of plausibility, and so bulking the creature out to turn it from an overgrown stork to a proper dragon is just a matter of saying that their muscles and bones are better than a pterosaur's -- by some factor that might still strain realistic biology (since Quetzalcoatlus was presumably already pretty damn optimized) but at least isn't off by full orders of magnitude.

Unless, of course, the killjoys are right and Quetzalcoatlus itself was flightless...

 

[Oofta]

Well, yes, but I'm not proposing reducing the dragon's density to the point where it would drift like a feather. A creature the size of a dragon, at 20% the density of normal flesh, would still fall quite fast if its wings were folded.

What I am trying to do is get to a creature that flies in the same manner as a large bird--the way most of us expect a dragon to fly, soaring majestically before it folds its wings and dives to spew fire. Umbran's solution of "just make it stronger" is a problem because no matter how strong the dragon is, the surface area of its wings determines how much lift it can generate per flap; Hercules cannot fly by flapping his arms. As you pointed out earlier, a dragon relying purely on stronger wings would have to fly like a colossal hummingbird, beating its wings at blurring speeds, and it would have to do this all the time. It could not soar or glide. As soon as its wings stopped moving or even slowed down, it would plummet.

Alternatively, the dragon could use its strength to make its wings bigger. But this leads to a dragon with a 40-foot body and 1,000-foot wingspan.

The blimp-dragon is the end result of "just make it lighter." Again, though, such a dragon's flight would look very different from what we expect. It would not so much fly as swim through the air. When at rest, it would simply drift above the ground. That fits nicely with Eastern-style dragons, which are generally portrayed without any wings at all. But for Western-style dragons, it would look utterly bizarre.

So, the middle ground is a place where we make the dragon strong enough to support a reasonably larger wing surface, and light enough for those wings to lift it in a birdlike way, without making its wings absurdly outsized and without making it so light that it cannot fall.

All of that is fine, but at some point magic needs to be involved. Dragons as we know them could not exist without magic. That doesn't mean that like beholders they can only fly because of magic, just that they are magically lighter than their mass would indicate.

To me that makes sense. If there is magic, evolution will at least in some cases take advantage of it. So a dragon (at least while flying) weighs as much as a very large bird and it's bones are supernaturally strong. Of course it's scales are also supernaturally strong and it breaths fire so it's just part of the package.